linux_commands_db_comprehensive.json

{
  "_meta": {
    "description": "Comprehensive Linux Commands Database with Educational Content",
    "version": "2.0",
    "categories": ["file_operations", "text_processing", "system_info", "process_management", "network", "compression", "permissions", "user_management", "disk_management", "package_management"]
  },
  
  "command_combinations": {
    "find_and_delete": {
      "description": "Find and delete files matching a pattern",
      "command": "find . -name '*.tmp' -type f -delete",
      "explanation": "Searches current directory for .tmp files and deletes them. -type f ensures only files, not directories",
      "safer_alternative": "find . -name '*.tmp' -type f -exec rm -i {} \\;",
      "tags": ["find", "delete", "cleanup", "combination"]
    },
    "grep_count_occurrences": {
      "description": "Count occurrences of a pattern in files",
      "command": "grep -r 'pattern' . | wc -l",
      "explanation": "grep searches recursively, wc -l counts the lines (occurrences)",
      "tags": ["grep", "wc", "count", "combination"]
    },
    "list_by_size": {
      "description": "List files sorted by size",
      "command": "ls -lhS",
      "explanation": "-l (long format), -h (human readable sizes), -S (sort by size, largest first)",
      "tags": ["ls", "sort", "size"]
    },
    "list_by_date": {
      "description": "List files sorted by modification time",
      "command": "ls -lht",
      "explanation": "-t sorts by time (newest first), combine with -r for oldest first",
      "tags": ["ls", "sort", "date", "time"]
    },
    "disk_usage_sorted": {
      "description": "Show disk usage sorted by size",
      "command": "du -sh * | sort -rh",
      "explanation": "du shows disk usage, sort -rh sorts reverse (-r) human-readable (-h) numbers",
      "tags": ["du", "sort", "disk", "combination"]
    },
    "find_large_files": {
      "description": "Find files larger than 100MB",
      "command": "find . -type f -size +100M -exec ls -lh {} \\; | awk '{print $9, $5}'",
      "explanation": "Finds large files and displays name with size in human-readable format",
      "tags": ["find", "size", "large files", "combination"]
    },
    "count_files_by_extension": {
      "description": "Count files grouped by extension",
      "command": "find . -type f | sed 's/.*\\.//' | sort | uniq -c | sort -rn",
      "explanation": "Extracts extensions, sorts, counts unique ones, and sorts by frequency",
      "tags": ["find", "sed", "uniq", "count", "combination"]
    },
    "monitor_log_file": {
      "description": "Monitor log file in real-time",
      "command": "tail -f /var/log/syslog",
      "explanation": "-f follows the file, showing new lines as they're added. Press Ctrl+C to stop",
      "tags": ["tail", "log", "monitor", "realtime"]
    },
    "search_and_replace_files": {
      "description": "Search and replace text in multiple files",
      "command": "find . -type f -name '*.txt' -exec sed -i 's/old/new/g' {} +",
      "explanation": "Finds .txt files and replaces old with new in-place. Remove -i to preview first",
      "safer_alternative": "find . -type f -name '*.txt' -exec sed 's/old/new/g' {} +",
      "tags": ["find", "sed", "replace", "combination"]
    },
    "top_processes_by_memory": {
      "description": "Show top 10 processes using most memory",
      "command": "ps aux --sort=-%mem | head -11",
      "explanation": "Lists processes sorted by memory usage, head shows top 10 (11 includes header)",
      "tags": ["ps", "memory", "sort", "combination"]
    },
    "top_processes_by_cpu": {
      "description": "Show top 10 processes using most CPU",
      "command": "ps aux --sort=-%cpu | head -11",
      "explanation": "Lists processes sorted by CPU usage (descending)",
      "tags": ["ps", "cpu", "sort", "combination"]
    },
    "find_listening_ports": {
      "description": "Find all listening network ports",
      "command": "netstat -tuln | grep LISTEN",
      "explanation": "-t (TCP), -u (UDP), -l (listening), -n (numeric), grep filters listening ports",
      "alternative": "ss -tuln | grep LISTEN",
      "tags": ["netstat", "ss", "port", "network", "combination"]
    },
    "check_port_usage": {
      "description": "Check what's using a specific port",
      "command": "lsof -i :8080",
      "explanation": "Shows process using port 8080. May need sudo for all processes",
      "tags": ["lsof", "port", "network"]
    },
    "archive_directory": {
      "description": "Create compressed archive of directory",
      "command": "tar -czf archive.tar.gz /path/to/directory",
      "explanation": "-c (create), -z (gzip), -f (file). Use -j for bzip2, -J for xz compression",
      "tags": ["tar", "compress", "archive", "backup"]
    },
    "extract_archive": {
      "description": "Extract compressed archive",
      "command": "tar -xzf archive.tar.gz",
      "explanation": "-x (extract), -z (gzip), -f (file). tar auto-detects compression type",
      "tags": ["tar", "extract", "decompress"]
    },
    "find_recently_modified": {
      "description": "Find files modified in last 24 hours",
      "command": "find . -type f -mtime -1",
      "explanation": "-mtime -1 means less than 1 day ago. Use -mmin -60 for last 60 minutes",
      "tags": ["find", "modified", "recent", "time"]
    },
    "disk_space_by_directory": {
      "description": "Show disk usage for each directory",
      "command": "du -h --max-depth=1 | sort -rh",
      "explanation": "Shows size of immediate subdirectories, sorted largest first",
      "tags": ["du", "disk", "directory", "sort", "combination"]
    },
    "count_lines_in_files": {
      "description": "Count total lines across all files",
      "command": "find . -type f -name '*.py' -exec wc -l {} + | tail -1",
      "explanation": "Counts lines in all Python files, tail shows total",
      "tags": ["find", "wc", "count", "lines", "combination"]
    },
    "kill_processes_by_name": {
      "description": "Kill all processes matching a name",
      "command": "pkill -f 'process_name'",
      "explanation": "-f matches full command line. Use killall for exact name match",
      "safer_alternative": "pgrep -f 'process_name' (to see what would be killed first)",
      "tags": ["pkill", "kill", "process"]
    },
    "watch_command_output": {
      "description": "Run command repeatedly and watch output",
      "command": "watch -n 2 'df -h'",
      "explanation": "Runs df -h every 2 seconds. Press Ctrl+C to stop",
      "tags": ["watch", "monitor", "repeat"]
    },
    "find_duplicate_files": {
      "description": "Find duplicate files by content",
      "command": "find . -type f -exec md5sum {} + | sort | uniq -w32 -D",
      "explanation": "Calculates MD5 hash of each file, finds duplicates by hash",
      "tags": ["find", "md5sum", "duplicate", "combination"]
    },
    "recursive_grep_with_context": {
      "description": "Search with surrounding context lines",
      "command": "grep -rn -A 3 -B 3 'pattern' .",
      "explanation": "-r (recursive), -n (line numbers), -A (lines after), -B (lines before)",
      "tags": ["grep", "search", "context"]
    },
    "find_empty_files": {
      "description": "Find empty files and directories",
      "command": "find . -empty",
      "explanation": "Finds both empty files (0 bytes) and empty directories",
      "tags": ["find", "empty"]
    },
    "parallel_compression": {
      "description": "Compress using multiple CPU cores",
      "command": "tar -I pigz -cf archive.tar.gz directory/",
      "explanation": "Uses pigz (parallel gzip) for faster compression on multi-core systems",
      "alternative": "tar -I 'xz -T0' -cf archive.tar.xz directory/ (for xz compression)",
      "tags": ["tar", "compression", "parallel", "performance"]
    },
    "batch_rename_files": {
      "description": "Rename multiple files using pattern",
      "command": "for f in *.txt; do mv \"$f\" \"${f%.txt}.md\"; done",
      "explanation": "Changes all .txt files to .md. ${f%.txt} removes .txt extension",
      "tags": ["rename", "batch", "loop"]
    },
    "find_and_grep": {
      "description": "Find files and search content",
      "command": "find . -name '*.log' -exec grep -l 'ERROR' {} +",
      "explanation": "Finds .log files containing 'ERROR'. -l shows only filenames",
      "tags": ["find", "grep", "combination", "search"]
    },
    "monitor_directory_changes": {
      "description": "Watch for file changes in directory",
      "command": "watch -d ls -l",
      "explanation": "-d highlights differences between updates",
      "tags": ["watch", "monitor", "files"]
    },
    "network_bandwidth_test": {
      "description": "Test network bandwidth between hosts",
      "command": "iperf3 -c server_ip",
      "explanation": "Measures TCP/UDP bandwidth. Run 'iperf3 -s' on server first",
      "tags": ["iperf", "network", "bandwidth", "performance"]
    },
    "csv_column_extraction": {
      "description": "Extract specific columns from CSV",
      "command": "cut -d',' -f1,3 file.csv",
      "explanation": "Extracts columns 1 and 3. -d sets delimiter, -f selects fields",
      "tags": ["cut", "csv", "column", "text processing"]
    },
    "json_pretty_print": {
      "description": "Pretty print JSON file",
      "command": "cat file.json | python -m json.tool",
      "explanation": "Formats JSON with proper indentation for readability",
      "alternative": "jq '.' file.json (if jq is installed)",
      "tags": ["json", "format", "pretty print"]
    }
  },
  
  "ls": {
    "description": "List directory contents - one of the most fundamental commands",
    "usage": "ls [OPTIONS] [FILE]...",
    "category": "file_operations",
    "tags": ["files", "directory", "list", "show", "basic"],
    "common_options": {
      "-l": "Long format with permissions, owner, size, date",
      "-a": "Show all files including hidden (starting with .)",
      "-h": "Human-readable sizes (KB, MB, GB)",
      "-t": "Sort by modification time, newest first",
      "-r": "Reverse sort order",
      "-S": "Sort by file size, largest first",
      "-R": "Recursive - list subdirectories too",
      "-i": "Show inode numbers",
      "-d": "List directories themselves, not contents"
    },
    "examples": [
      {
        "command": "ls -la",
        "explanation": "Long format showing all files including hidden"
      },
      {
        "command": "ls -lhS",
        "explanation": "Long format, human-readable sizes, sorted by size"
      },
      {
        "command": "ls -lt | head -10",
        "explanation": "Show 10 most recently modified files"
      },
      {
        "command": "ls -lR",
        "explanation": "Recursive listing of all subdirectories"
      }
    ],
    "tips": [
      "Combine multiple options: ls -lAhtr shows all files, long format, human sizes, sorted by time (oldest first)",
      "Use ls -d */ to list only directories",
      "ls -1 shows one file per line (useful for scripting)"
    ]
  },
  
  "cd": {
    "description": "Change directory - navigate filesystem",
    "usage": "cd [DIRECTORY]",
    "category": "file_operations",
    "tags": ["directory", "navigate", "change", "basic"],
    "special_paths": {
      "~": "Home directory",
      "-": "Previous directory",
      "..": "Parent directory",
      "../..": "Two levels up",
      ".": "Current directory (rarely needed)",
      "/": "Root directory"
    },
    "examples": [
      {
        "command": "cd /var/log",
        "explanation": "Change to absolute path"
      },
      {
        "command": "cd ~/Documents",
        "explanation": "Go to Documents in home directory"
      },
      {
        "command": "cd -",
        "explanation": "Switch to previous directory (toggle)"
      },
      {
        "command": "cd ../..",
        "explanation": "Go up two directory levels"
      }
    ],
    "tips": [
      "Use 'pushd' and 'popd' for directory stack navigation",
      "'cd' with no arguments goes to home directory",
      "Use Tab completion to avoid typing full paths"
    ]
  },
  
  "pwd": {
    "description": "Print working directory - show current location",
    "usage": "pwd [OPTIONS]",
    "category": "file_operations",
    "tags": ["directory", "current", "path", "location", "basic"],
    "common_options": {
      "-L": "Print logical path (with symlinks)",
      "-P": "Print physical path (resolve symlinks)"
    },
    "examples": [
      {
        "command": "pwd",
        "explanation": "Show current directory path"
      },
      {
        "command": "pwd -P",
        "explanation": "Show real path (resolve symbolic links)"
      }
    ],
    "tips": [
      "Useful in scripts to save current location: OLDPWD=$(pwd)",
      "Combine with command substitution: cd $(dirname $(pwd))"
    ]
  },
  
  "cat": {
    "description": "Concatenate and display file contents",
    "usage": "cat [OPTIONS] [FILE]...",
    "category": "file_operations",
    "tags": ["file", "read", "display", "show", "content", "basic"],
    "common_options": {
      "-n": "Number all output lines",
      "-b": "Number non-empty lines only",
      "-s": "Squeeze multiple blank lines into one",
      "-A": "Show all characters including non-printing",
      "-E": "Display $ at end of each line",
      "-T": "Display TAB characters as ^I"
    },
    "examples": [
      {
        "command": "cat file.txt",
        "explanation": "Display file contents"
      },
      {
        "command": "cat file1.txt file2.txt > combined.txt",
        "explanation": "Concatenate multiple files into one"
      },
      {
        "command": "cat -n script.py",
        "explanation": "Show file with line numbers"
      },
      {
        "command": "cat > newfile.txt",
        "explanation": "Create new file (type content, Ctrl+D to save)"
      }
    ],
    "tips": [
      "For large files, use 'less' or 'more' instead",
      "Use 'tac' to display file in reverse order",
      "cat without arguments reads from stdin (useful in pipes)"
    ]
  },
  
  "grep": {
    "description": "Search text using patterns - powerful text search tool",
    "usage": "grep [OPTIONS] PATTERN [FILE]...",
    "category": "text_processing",
    "tags": ["search", "find", "text", "pattern", "filter"],
    "common_options": {
      "-r": "Recursive search in directories",
      "-i": "Case-insensitive search",
      "-n": "Show line numbers",
      "-v": "Invert match (show non-matching lines)",
      "-l": "Show only filenames with matches",
      "-c": "Count matching lines",
      "-A NUM": "Show NUM lines after match",
      "-B NUM": "Show NUM lines before match",
      "-C NUM": "Show NUM lines before and after",
      "-w": "Match whole words only",
      "-E": "Extended regex (same as egrep)",
      "-o": "Show only matched part of line",
      "--color": "Highlight matches in color"
    },
    "examples": [
      {
        "command": "grep 'error' logfile.txt",
        "explanation": "Find lines containing 'error'"
      },
      {
        "command": "grep -rn 'TODO' .",
        "explanation": "Recursively search for 'TODO' with line numbers"
      },
      {
        "command": "grep -i 'warning' *.log",
        "explanation": "Case-insensitive search in all .log files"
      },
      {
        "command": "grep -v '^#' config.txt",
        "explanation": "Show lines not starting with # (exclude comments)"
      },
      {
        "command": "grep -E 'error|warning|critical' app.log",
        "explanation": "Search for multiple patterns (OR logic)"
      }
    ],
    "tips": [
      "Use grep -P for Perl-compatible regex",
      "Combine with other commands: ps aux | grep nginx",
      "Use grep -c to count occurrences instead of piping to wc -l"
    ]
  },
  
  "find": {
    "description": "Search for files and directories in hierarchy",
    "usage": "find [PATH] [OPTIONS] [EXPRESSION]",
    "category": "file_operations",
    "tags": ["search", "file", "locate", "recursive"],
    "common_options": {
      "-name": "Search by filename (case-sensitive)",
      "-iname": "Search by filename (case-insensitive)",
      "-type f": "Find files only",
      "-type d": "Find directories only",
      "-size +10M": "Files larger than 10MB",
      "-size -10k": "Files smaller than 10KB",
      "-mtime -7": "Modified in last 7 days",
      "-mtime +30": "Modified more than 30 days ago",
      "-user username": "Files owned by user",
      "-perm 755": "Files with specific permissions",
      "-exec": "Execute command on found files",
      "-delete": "Delete found files (use carefully!)",
      "-empty": "Find empty files/directories"
    },
    "examples": [
      {
        "command": "find . -name '*.txt'",
        "explanation": "Find all .txt files in current directory and subdirectories"
      },
      {
        "command": "find /home -type f -mtime -7",
        "explanation": "Find files modified in last 7 days"
      },
      {
        "command": "find . -size +100M -exec ls -lh {} \\;",
        "explanation": "Find large files and show their sizes"
      },
      {
        "command": "find . -name '*.log' -delete",
        "explanation": "Find and delete all .log files (careful!)"
      },
      {
        "command": "find . -type f -name '*.py' | wc -l",
        "explanation": "Count number of Python files"
      }
    ],
    "tips": [
      "Use -maxdepth N to limit search depth",
      "Combine multiple conditions: find . -name '*.txt' -size +1M",
      "Use -print0 with xargs -0 for filenames with spaces"
    ]
  },
  
  "awk": {
    "description": "Pattern scanning and text processing language",
    "usage": "awk 'pattern {action}' [FILE]",
    "category": "text_processing",
    "tags": ["text", "processing", "column", "format", "advanced"],
    "examples": [
      {
        "command": "awk '{print $1, $3}' file.txt",
        "explanation": "Print 1st and 3rd column from each line"
      },
      {
        "command": "awk -F',' '{print $2}' data.csv",
        "explanation": "Print 2nd column from comma-separated file"
      },
      {
        "command": "awk '/error/ {print $0}' log.txt",
        "explanation": "Print lines containing 'error'"
      },
      {
        "command": "awk '{sum+=$1} END {print sum}' numbers.txt",
        "explanation": "Sum values in first column"
      },
      {
        "command": "ps aux | awk '{print $2, $11}'",
        "explanation": "Show PID and command name from ps output"
      }
    ],
    "tips": [
      "$0 is the entire line, $1 is first field, $2 second field, etc.",
      "Use BEGIN and END blocks for initialization and summary",
      "Built-in variables: NR (line number), NF (number of fields)"
    ]
  },
  
  "sed": {
    "description": "Stream editor for filtering and transforming text",
    "usage": "sed [OPTIONS] 'command' [FILE]",
    "category": "text_processing",
    "tags": ["text", "edit", "replace", "stream", "advanced"],
    "common_options": {
      "-i": "Edit files in-place (modify original)",
      "-e": "Multiple editing commands",
      "-n": "Suppress automatic output",
      "-r": "Use extended regex"
    },
    "examples": [
      {
        "command": "sed 's/old/new/g' file.txt",
        "explanation": "Replace all occurrences of 'old' with 'new'"
      },
      {
        "command": "sed -i 's/foo/bar/g' file.txt",
        "explanation": "Replace in-place (modify file directly)"
      },
      {
        "command": "sed -n '10,20p' file.txt",
        "explanation": "Print lines 10 to 20"
      },
      {
        "command": "sed '/pattern/d' file.txt",
        "explanation": "Delete lines matching pattern"
      },
      {
        "command": "sed 's/^/PREFIX: /' file.txt",
        "explanation": "Add prefix to each line"
      }
    ],
    "tips": [
      "Test without -i first to preview changes",
      "Use sed -i.bak to create backup before modifying",
      "Combine multiple commands: sed -e 's/a/b/' -e 's/c/d/'"
    ]
  },
  
  "ps": {
    "description": "Report process status - show running processes",
    "usage": "ps [OPTIONS]",
    "category": "process_management",
    "tags": ["process", "running", "tasks", "list", "system"],
    "common_options": {
      "aux": "All processes, user-oriented format",
      "ef": "All processes, full format",
      "-u username": "Processes for specific user",
      "--sort=-%mem": "Sort by memory usage",
      "--sort=-%cpu": "Sort by CPU usage"
    },
    "examples": [
      {
        "command": "ps aux",
        "explanation": "Show all running processes with detailed info"
      },
      {
        "command": "ps aux | grep nginx",
        "explanation": "Find nginx processes"
      },
      {
        "command": "ps aux --sort=-%mem | head -10",
        "explanation": "Top 10 memory-consuming processes"
      },
      {
        "command": "ps -ef | grep python",
        "explanation": "Find all Python processes"
      }
    ],
    "tips": [
      "Use 'top' or 'htop' for real-time monitoring",
      "ps aux shows: USER, PID, %CPU, %MEM, COMMAND",
      "Combine with pgrep for specific searches"
    ]
  },
  
  "top": {
    "description": "Display and update sorted information about processes",
    "usage": "top [OPTIONS]",
    "category": "process_management",
    "tags": ["process", "monitor", "cpu", "memory", "performance", "realtime"],
    "interactive_keys": {
      "q": "Quit",
      "k": "Kill a process",
      "M": "Sort by memory usage",
      "P": "Sort by CPU usage",
      "T": "Sort by running time",
      "u": "Filter by user",
      "1": "Show individual CPU cores",
      "h": "Help"
    },
    "examples": [
      {
        "command": "top",
        "explanation": "Interactive process monitor"
      },
      {
        "command": "top -u username",
        "explanation": "Show processes for specific user"
      },
      {
        "command": "top -bn1 | head -20",
        "explanation": "Non-interactive snapshot of top processes"
      }
    ],
    "tips": [
      "Press 'M' to sort by memory, 'P' for CPU",
      "Use 'htop' for a more user-friendly interface",
      "top shows load average in first line: 1min, 5min, 15min"
    ]
  },
  
  "df": {
    "description": "Report file system disk space usage",
    "usage": "df [OPTIONS] [FILE]...",
    "category": "disk_management",
    "tags": ["disk", "space", "usage", "storage", "filesystem"],
    "common_options": {
      "-h": "Human-readable sizes (GB, MB)",
      "-i": "Show inode information",
      "-T": "Show filesystem type",
      "-a": "Include pseudo filesystems",
      "--total": "Show grand total"
    },
    "examples": [
      {
        "command": "df -h",
        "explanation": "Show disk space in human-readable format"
      },
      {
        "command": "df -hT",
        "explanation": "Include filesystem types"
      },
      {
        "command": "df -i",
        "explanation": "Show inode usage (file count limits)"
      },
      {
        "command": "df -h /home",
        "explanation": "Check space for specific mount point"
      }
    ],
    "tips": [
      "Use 'du' to see disk usage by directory",
      "If df shows 100% but files deleted, check for open file handles with lsof",
      "Watch out for inode exhaustion (df -i)"
    ]
  },
  
  "du": {
    "description": "Estimate file space usage - disk usage by directory",
    "usage": "du [OPTIONS] [FILE]...",
    "category": "disk_management",
    "tags": ["disk", "usage", "size", "directory", "space"],
    "common_options": {
      "-h": "Human-readable sizes",
      "-s": "Summary only (total for each argument)",
      "-c": "Grand total",
      "--max-depth=N": "Limit directory depth",
      "-a": "Include files, not just directories",
      "--exclude": "Exclude pattern"
    },
    "examples": [
      {
        "command": "du -sh *",
        "explanation": "Show size of each item in current directory"
      },
      {
        "command": "du -h --max-depth=1 | sort -rh",
        "explanation": "Show directory sizes sorted by size"
      },
      {
        "command": "du -sh /var/log",
        "explanation": "Total size of /var/log directory"
      },
      {
        "command": "du -ah | sort -rh | head -20",
        "explanation": "Find 20 largest files/directories"
      }
    ],
    "tips": [
      "du counts actual disk usage (considers hard links)",
      "For fast estimates, use --apparent-size",
      "Use ncdu for interactive disk usage explorer"
    ]
  },
  
  "free": {
    "description": "Display amount of free and used memory in the system",
    "usage": "free [OPTIONS]",
    "category": "system_info",
    "tags": ["memory", "ram", "usage", "available", "system"],
    "common_options": {
      "-h": "Human-readable output",
      "-m": "Show in megabytes",
      "-g": "Show in gigabytes",
      "-s N": "Update every N seconds",
      "-t": "Show total line"
    },
    "examples": [
      {
        "command": "free -h",
        "explanation": "Show memory usage in human-readable format"
      },
      {
        "command": "free -m -s 2",
        "explanation": "Show memory in MB, update every 2 seconds"
      },
      {
        "command": "free -ht",
        "explanation": "Human-readable with total line"
      }
    ],
    "tips": [
      "'available' column shows memory available for new apps",
      "Buffers/cache is memory used for system caching (reclaimable)",
      "Don't worry if 'free' is low - Linux uses free RAM for caching"
    ]
  },
  
  "tar": {
    "description": "Archive utility - create and extract tar archives",
    "usage": "tar [OPTIONS] [FILE]...",
    "category": "compression",
    "tags": ["archive", "compress", "extract", "backup"],
    "common_options": {
      "-c": "Create archive",
      "-x": "Extract archive",
      "-t": "List contents",
      "-f": "Specify filename",
      "-z": "gzip compression",
      "-j": "bzip2 compression",
      "-J": "xz compression",
      "-v": "Verbose output",
      "-C": "Extract to specific directory"
    },
    "examples": [
      {
        "command": "tar -czf backup.tar.gz /data",
        "explanation": "Create gzip-compressed archive of /data"
      },
      {
        "command": "tar -xzf backup.tar.gz",
        "explanation": "Extract gzip-compressed archive"
      },
      {
        "command": "tar -tzf backup.tar.gz",
        "explanation": "List contents without extracting"
      },
      {
        "command": "tar -xzf file.tar.gz -C /destination",
        "explanation": "Extract to specific directory"
      },
      {
        "command": "tar -cjf archive.tar.bz2 dir/",
        "explanation": "Create bzip2-compressed archive (better compression)"
      }
    ],
    "tips": [
      "Remember: tar -czf creates, tar -xzf extracts",
      "Modern tar auto-detects compression: tar -xf works for any format",
      "Use -v to see progress during operations"
    ]
  },
  
  "wget": {
    "description": "Download files from the web - non-interactive downloader",
    "usage": "wget [OPTIONS] [URL]",
    "category": "network",
    "tags": ["download", "web", "http", "fetch", "transfer"],
    "common_options": {
      "-O": "Output to specific file",
      "-c": "Continue partial download",
      "-r": "Recursive download",
      "-np": "No parent directories (with -r)",
      "-q": "Quiet mode",
      "-P": "Prefix directory for downloads",
      "--limit-rate": "Limit download speed"
    },
    "examples": [
      {
        "command": "wget https://example.com/file.zip",
        "explanation": "Download file"
      },
      {
        "command": "wget -c https://example.com/large-file.iso",
        "explanation": "Resume interrupted download"
      },
      {
        "command": "wget -O custom-name.zip https://example.com/file.zip",
        "explanation": "Save with custom filename"
      },
      {
        "command": "wget -r -np https://example.com/docs/",
        "explanation": "Recursively download website section"
      }
    ],
    "tips": [
      "Use -c to resume downloads if connection drops",
      "wget keeps retrying if network is unstable",
      "For single file downloads, curl is more flexible"
    ]
  },
  
  "curl": {
    "description": "Transfer data from or to a server - versatile data transfer tool",
    "usage": "curl [OPTIONS] [URL]",
    "category": "network",
    "tags": ["http", "download", "api", "web", "request", "transfer"],
    "common_options": {
      "-O": "Save with remote filename",
      "-o": "Save to specific file",
      "-I": "Fetch headers only",
      "-L": "Follow redirects",
      "-X": "Specify request method (GET, POST, etc.)",
      "-d": "Send data (for POST)",
      "-H": "Add custom header",
      "-u": "User authentication",
      "-v": "Verbose output",
      "-s": "Silent mode"
    },
    "examples": [
      {
        "command": "curl https://api.example.com/data",
        "explanation": "Fetch URL content"
      },
      {
        "command": "curl -I https://example.com",
        "explanation": "Get HTTP headers only"
      },
      {
        "command": "curl -X POST -d 'key=value' https://api.example.com",
        "explanation": "Send POST request with data"
      },
      {
        "command": "curl -H 'Authorization: Bearer token' https://api.example.com",
        "explanation": "Add custom header (API authentication)"
      },
      {
        "command": "curl -o file.html https://example.com",
        "explanation": "Download and save to file"
      }
    ],
    "tips": [
      "Use -L to follow redirects (important for many sites)",
      "curl is better for APIs, wget for downloading files",
      "Add | jq for pretty JSON formatting"
    ]
  },
  
  "chmod": {
    "description": "Change file permissions - control who can read/write/execute",
    "usage": "chmod [OPTIONS] MODE FILE...",
    "category": "permissions",
    "tags": ["permissions", "access", "rights", "security"],
    "permission_numbers": {
      "7": "rwx (read, write, execute)",
      "6": "rw- (read, write)",
      "5": "r-x (read, execute)",
      "4": "r-- (read only)",
      "3": "-wx (write, execute)",
      "2": "-w- (write only)",
      "1": "--x (execute only)",
      "0": "--- (no permissions)"
    },
    "symbolic_modes": {
      "u": "User/owner",
      "g": "Group",
      "o": "Others",
      "a": "All (ugo)",
      "+": "Add permission",
      "-": "Remove permission",
      "=": "Set exact permission"
    },
    "examples": [
      {
        "command": "chmod 755 script.sh",
        "explanation": "Owner: rwx, Group: r-x, Others: r-x"
      },
      {
        "command": "chmod +x file.sh",
        "explanation": "Add execute permission for all"
      },
      {
        "command": "chmod u+x,g-w file",
        "explanation": "Add execute for owner, remove write for group"
      },
      {
        "command": "chmod -R 644 directory/",
        "explanation": "Recursively set permissions (files: rw-r--r--)"
      }
    ],
    "tips": [
      "755 for scripts/executables, 644 for regular files",
      "Never use 777 unless absolutely necessary (security risk)",
      "Use chmod -R carefully on directories"
    ]
  },
  
  "chown": {
    "description": "Change file owner and group",
    "usage": "chown [OPTIONS] OWNER[:GROUP] FILE...",
    "category": "permissions",
    "tags": ["ownership", "user", "group", "permissions"],
    "common_options": {
      "-R": "Recursive (for directories)",
      "-v": "Verbose output",
      "--reference": "Use ownership of reference file"
    },
    "examples": [
      {
        "command": "chown user file.txt",
        "explanation": "Change owner to 'user'"
      },
      {
        "command": "chown user:group file.txt",
        "explanation": "Change owner and group"
      },
      {
        "command": "chown -R user:group directory/",
        "explanation": "Recursively change ownership"
      },
      {
        "command": "chown :group file.txt",
        "explanation": "Change group only (keep owner)"
      }
    ],
    "tips": [
      "Usually requires sudo/root privileges",
      "Use chgrp to change group only",
      "Check current ownership with ls -l"
    ]
  },
  
  "ln": {
    "description": "Make links between files - create shortcuts",
    "usage": "ln [OPTIONS] TARGET LINK_NAME",
    "category": "file_operations",
    "tags": ["link", "symbolic", "shortcut", "symlink"],
    "link_types": {
      "hard": "Direct reference to file data (same inode)",
      "symbolic": "Pointer to filename (can cross filesystems)"
    },
    "common_options": {
      "-s": "Create symbolic link (recommended)",
      "-f": "Force (remove existing destination)",
      "-n": "Treat symlink to directory as file",
      "-v": "Verbose output"
    },
    "examples": [
      {
        "command": "ln -s /path/to/file linkname",
        "explanation": "Create symbolic link"
      },
      {
        "command": "ln -s /opt/app/current /usr/local/bin/app",
        "explanation": "Create symlink for easy access"
      },
      {
        "command": "ln file hardlink",
        "explanation": "Create hard link (no -s)"
      }
    ],
    "tips": [
      "Always use absolute paths with symlinks",
      "Symbolic links can point to non-existent files (check with ls -l)",
      "Hard links can't cross filesystems or link to directories"
    ]
  },
  
  "netstat": {
    "description": "Network statistics - show network connections, routing tables",
    "usage": "netstat [OPTIONS]",
    "category": "network",
    "tags": ["network", "connections", "ports", "sockets", "statistics"],
    "common_options": {
      "-t": "TCP connections",
      "-u": "UDP connections",
      "-l": "Listening sockets only",
      "-n": "Numeric addresses (don't resolve names)",
      "-p": "Show program/PID",
      "-a": "All sockets",
      "-r": "Routing table",
      "-s": "Statistics by protocol"
    },
    "examples": [
      {
        "command": "netstat -tuln",
        "explanation": "Show all TCP/UDP listening ports"
      },
      {
        "command": "netstat -tunap",
        "explanation": "Show all connections with program names"
      },
      {
        "command": "netstat -rn",
        "explanation": "Show routing table"
      },
      {
        "command": "netstat -s",
        "explanation": "Show network statistics"
      }
    ],
    "tips": [
      "Use ss instead of netstat (faster, more info)",
      "netstat -tulnp | grep :80 to check specific port",
      "May need sudo to see all process names"
    ]
  },
  
  "ss": {
    "description": "Socket statistics - modern replacement for netstat",
    "usage": "ss [OPTIONS]",
    "category": "network",
    "tags": ["network", "sockets", "connections", "ports"],
    "common_options": {
      "-t": "TCP sockets",
      "-u": "UDP sockets",
      "-l": "Listening sockets",
      "-n": "Numeric addresses",
      "-p": "Show processes",
      "-a": "All sockets",
      "-s": "Summary statistics"
    },
    "examples": [
      {
        "command": "ss -tuln",
        "explanation": "Show listening TCP/UDP ports"
      },
      {
        "command": "ss -tunap",
        "explanation": "Show all connections with processes"
      },
      {
        "command": "ss -s",
        "explanation": "Show socket statistics summary"
      },
      {
        "command": "ss -t state established",
        "explanation": "Show established TCP connections"
      }
    ],
    "tips": [
      "ss is faster than netstat for large systems",
      "Use ss -o to show timer information",
      "ss can filter by state, address, port"
    ]
  },
  
  "ping": {
    "description": "Send ICMP ECHO_REQUEST to network hosts - test connectivity",
    "usage": "ping [OPTIONS] destination",
    "category": "network",
    "tags": ["network", "connectivity", "test", "reachability", "icmp"],
    "common_options": {
      "-c N": "Send N packets then stop",
      "-i N": "Wait N seconds between packets",
      "-s SIZE": "Packet size in bytes",
      "-W N": "Timeout in seconds",
      "-q": "Quiet output (summary only)",
      "-f": "Flood ping (requires root)"
    },
    "examples": [
      {
        "command": "ping google.com",
        "explanation": "Test connectivity to google.com"
      },
      {
        "command": "ping -c 4 8.8.8.8",
        "explanation": "Send 4 packets to Google DNS"
      },
      {
        "command": "ping -i 2 -c 10 example.com",
        "explanation": "Ping every 2 seconds, 10 times"
      }
    ],
    "tips": [
      "Press Ctrl+C to stop continuous ping",
      "Low ping = good, high ping or packet loss = network issues",
      "Use ping6 for IPv6 addresses"
    ]
  },
  
  "traceroute": {
    "description": "Trace route to network host - show path packets take",
    "usage": "traceroute [OPTIONS] host",
    "category": "network",
    "tags": ["network", "route", "path", "hops", "diagnostic"],
    "examples": [
      {
        "command": "traceroute google.com",
        "explanation": "Show route to google.com"
      },
      {
        "command": "traceroute -n 8.8.8.8",
        "explanation": "Don't resolve hostnames (faster)"
      }
    ],
    "tips": [
      "Each line shows a hop in the route",
      "*** means that hop doesn't respond",
      "Use mtr for continuous traceroute monitoring"
    ]
  },
  
  "kill": {
    "description": "Send signal to process - terminate or control processes",
    "usage": "kill [OPTIONS] PID",
    "category": "process_management",
    "tags": ["process", "terminate", "signal", "stop"],
    "common_signals": {
      "15 (TERM)": "Graceful termination (default)",
      "9 (KILL)": "Force kill (immediate, no cleanup)",
      "1 (HUP)": "Hangup (often reloads config)",
      "2 (INT)": "Interrupt (Ctrl+C)",
      "3 (QUIT)": "Quit with core dump",
      "18 (CONT)": "Continue if stopped",
      "19 (STOP)": "Stop process (pause)"
    },
    "examples": [
      {
        "command": "kill 1234",
        "explanation": "Gracefully terminate process 1234"
      },
      {
        "command": "kill -9 1234",
        "explanation": "Force kill process 1234"
      },
      {
        "command": "kill -HUP 1234",
        "explanation": "Send HUP signal (often reloads config)"
      },
      {
        "command": "killall nginx",
        "explanation": "Kill all processes named nginx"
      }
    ],
    "tips": [
      "Always try kill (TERM) before kill -9",
      "Use pkill to kill by name: pkill firefox",
      "Get PID with ps, pgrep, or top"
    ]
  },
  
  "systemctl": {
    "description": "Control systemd system and service manager",
    "usage": "systemctl [OPTIONS] COMMAND [NAME]",
    "category": "system_info",
    "tags": ["service", "daemon", "systemd", "start", "stop", "system"],
    "common_commands": {
      "start": "Start service",
      "stop": "Stop service",
      "restart": "Restart service",
      "reload": "Reload config without restart",
      "status": "Show service status",
      "enable": "Start on boot",
      "disable": "Don't start on boot",
      "is-active": "Check if running",
      "is-enabled": "Check if starts on boot",
      "list-units": "List all units"
    },
    "examples": [
      {
        "command": "systemctl status nginx",
        "explanation": "Check nginx service status"
      },
      {
        "command": "systemctl restart apache2",
        "explanation": "Restart Apache web server"
      },
      {
        "command": "systemctl enable ssh",
        "explanation": "Enable SSH to start on boot"
      },
      {
        "command": "systemctl list-units --type=service",
        "explanation": "List all services"
      }
    ],
    "tips": [
      "Most commands require sudo",
      "Use systemctl daemon-reload after editing unit files",
      "View logs with journalctl -u service-name"
    ]
  },
  
  "journalctl": {
    "description": "Query systemd journal logs",
    "usage": "journalctl [OPTIONS]",
    "category": "system_info",
    "tags": ["log", "journal", "systemd", "messages", "debug"],
    "common_options": {
      "-u": "Show logs for specific unit/service",
      "-f": "Follow logs (like tail -f)",
      "-n N": "Show last N lines",
      "-b": "Show logs since last boot",
      "--since": "Show logs since time",
      "--until": "Show logs until time",
      "-p": "Filter by priority (err, warning, info)",
      "-x": "Add explanatory help text",
      "-e": "Jump to end"
    },
    "examples": [
      {
        "command": "journalctl -xe",
        "explanation": "Show recent logs with explanations"
      },
      {
        "command": "journalctl -u nginx -f",
        "explanation": "Follow nginx logs in real-time"
      },
      {
        "command": "journalctl --since today",
        "explanation": "Show logs from today"
      },
      {
        "command": "journalctl -p err -b",
        "explanation": "Show errors since last boot"
      }
    ],
    "tips": [
      "Use --no-pager for scripts",
      "journalctl --disk-usage shows space used by logs",
      "Navigate with arrow keys, space, and q to quit"
    ]
  },
  
  "cron": {
    "description": "Time-based job scheduler - run tasks automatically",
    "usage": "crontab [OPTIONS]",
    "category": "system_info",
    "tags": ["schedule", "automation", "periodic", "task"],
    "cron_format": "* * * * * command_to_execute",
    "field_meaning": [
      "minute (0-59)",
      "hour (0-23)",
      "day of month (1-31)",
      "month (1-12)",
      "day of week (0-7, 0 and 7 are Sunday)"
    ],
    "special_strings": {
      "@reboot": "Run once at startup",
      "@daily": "Run once a day (midnight)",
      "@hourly": "Run once an hour",
      "@weekly": "Run once a week",
      "@monthly": "Run once a month"
    },
    "examples": [
      {
        "command": "crontab -e",
        "explanation": "Edit cron jobs for current user"
      },
      {
        "command": "crontab -l",
        "explanation": "List current cron jobs"
      },
      {
        "command": "0 2 * * * /backup.sh",
        "explanation": "Run backup script daily at 2 AM"
      },
      {
        "command": "*/15 * * * * /check.sh",
        "explanation": "Run check script every 15 minutes"
      }
    ],
    "tips": [
      "Use full paths in cron jobs (PATH may differ)",
      "Redirect output: command >> /var/log/cron.log 2>&1",
      "Test your command manually before adding to cron"
    ]
  },
  
  "lsblk": {
    "description": "List information about block devices - shows disks and partitions",
    "usage": "lsblk [OPTIONS] [DEVICE]",
    "category": "disk_management",
    "tags": ["disk", "partition", "block", "device", "storage"],
    "common_options": {
      "-f": "Show filesystem information",
      "-a": "Show all devices including empty ones",
      "-o": "Specify output columns",
      "-p": "Print full device paths",
      "-S": "Show SCSI devices only",
      "-t": "Show topology information"
    },
    "examples": [
      {
        "command": "lsblk",
        "explanation": "List all block devices in tree format"
      },
      {
        "command": "lsblk -f",
        "explanation": "Show filesystems, UUIDs, and mount points"
      },
      {
        "command": "lsblk -o NAME,SIZE,TYPE,MOUNTPOINT",
        "explanation": "Custom column output"
      }
    ],
    "tips": [
      "Use lsblk -f to see filesystem types and UUIDs",
      "Combine with grep: lsblk | grep disk",
      "Shows device hierarchy (disk → partitions)"
    ]
  },
  
  "fdisk": {
    "description": "Partition table manipulator for Linux - manage disk partitions",
    "usage": "fdisk [OPTIONS] DEVICE",
    "category": "disk_management",
    "tags": ["partition", "disk", "management", "format"],
    "common_options": {
      "-l": "List partition tables",
      "-u": "Use sectors instead of cylinders"
    },
    "examples": [
      {
        "command": "sudo fdisk -l",
        "explanation": "List all partition tables (requires root)"
      },
      {
        "command": "sudo fdisk /dev/sda",
        "explanation": "Open fdisk for /dev/sda (interactive mode)"
      }
    ],
    "tips": [
      "Always use 'sudo' with fdisk",
      "Use 'p' in interactive mode to print partition table",
      "Use 'w' to write changes (careful!), 'q' to quit without saving",
      "For GPT partitions, use 'gdisk' or 'parted' instead"
    ]
  },
  
  "iostat": {
    "description": "Report CPU and I/O statistics - monitor disk performance",
    "usage": "iostat [OPTIONS] [INTERVAL] [COUNT]",
    "category": "system_info",
    "tags": ["io", "disk", "performance", "statistics", "monitor"],
    "common_options": {
      "-x": "Extended statistics",
      "-k": "Display in kilobytes",
      "-m": "Display in megabytes",
      "-d": "Display only device statistics",
      "-c": "Display only CPU statistics",
      "-t": "Print timestamp"
    },
    "examples": [
      {
        "command": "iostat",
        "explanation": "Show CPU and device statistics once"
      },
      {
        "command": "iostat -x 1 5",
        "explanation": "Extended stats, update every 1 second, 5 times"
      },
      {
        "command": "iostat -d -k 2",
        "explanation": "Device stats in KB, update every 2 seconds"
      }
    ],
    "tips": [
      "High %util indicates disk bottleneck",
      "Watch await (average wait time) for slow disks",
      "Part of sysstat package - may need to install"
    ]
  },
  
  "lsof": {
    "description": "List open files - shows which processes have which files open",
    "usage": "lsof [OPTIONS] [FILE]",
    "category": "system_info",
    "tags": ["files", "open", "process", "port", "network"],
    "common_options": {
      "-i": "List network connections",
      "-i :PORT": "Show what's using specific port",
      "-u USER": "Show files opened by user",
      "-p PID": "Show files opened by process",
      "-t": "Terse output (PIDs only)",
      "+D DIR": "Show processes using files in directory"
    },
    "examples": [
      {
        "command": "lsof -i :8080",
        "explanation": "Show what's using port 8080"
      },
      {
        "command": "lsof -u username",
        "explanation": "Show all files opened by user"
      },
      {
        "command": "lsof +D /var/log",
        "explanation": "Show processes using /var/log files"
      },
      {
        "command": "lsof -i TCP:1-1024",
        "explanation": "Show processes using privileged ports"
      }
    ],
    "tips": [
      "May require sudo for full results",
      "Use lsof -i to debug 'address already in use' errors",
      "Combine with grep: lsof -i | grep LISTEN"
    ]
  },
  
  "dmesg": {
    "description": "Display kernel ring buffer messages - system boot and hardware logs",
    "usage": "dmesg [OPTIONS]",
    "category": "system_info",
    "tags": ["kernel", "boot", "hardware", "log", "debug"],
    "common_options": {
      "-T": "Human-readable timestamps",
      "-L": "Color output",
      "-l": "Filter by log level",
      "-w": "Wait for new messages (follow)",
      "-C": "Clear ring buffer",
      "--level": "Filter by level (err, warn, info)"
    },
    "examples": [
      {
        "command": "dmesg",
        "explanation": "Show all kernel messages"
      },
      {
        "command": "dmesg -T",
        "explanation": "Show with human-readable timestamps"
      },
      {
        "command": "dmesg | grep -i error",
        "explanation": "Find error messages"
      },
      {
        "command": "dmesg -w",
        "explanation": "Follow new kernel messages in real-time"
      },
      {
        "command": "dmesg --level=err,warn",
        "explanation": "Show only errors and warnings"
      }
    ],
    "tips": [
      "Useful for debugging hardware issues",
      "Check after system boot for problems",
      "Look for USB device info: dmesg | grep -i usb"
    ]
  },
  
  "vmstat": {
    "description": "Report virtual memory statistics - system performance overview",
    "usage": "vmstat [OPTIONS] [INTERVAL] [COUNT]",
    "category": "system_info",
    "tags": ["memory", "virtual", "performance", "statistics", "cpu"],
    "common_options": {
      "-a": "Active/inactive memory",
      "-s": "Memory statistics summary",
      "-d": "Disk statistics",
      "-p": "Partition statistics",
      "-S": "Units (k, K, m, M)"
    },
    "examples": [
      {
        "command": "vmstat",
        "explanation": "Show current system statistics"
      },
      {
        "command": "vmstat 2 5",
        "explanation": "Update every 2 seconds, 5 times"
      },
      {
        "command": "vmstat -s",
        "explanation": "Show memory statistics summary"
      }
    ],
    "tips": [
      "High 'si' and 'so' indicate swapping (bad for performance)",
      "Watch 'r' column for CPU queue length",
      "First line shows averages since boot"
    ]
  },
  
  "blkid": {
    "description": "Locate and print block device attributes - UUIDs, filesystems",
    "usage": "blkid [OPTIONS] [DEVICE]",
    "category": "disk_management",
    "tags": ["block", "device", "uuid", "filesystem", "partition"],
    "common_options": {
      "-o": "Output format (value, device, list, full)",
      "-s": "Show specific tag",
      "-t": "Search by tag"
    },
    "examples": [
      {
        "command": "blkid",
        "explanation": "Show all block device attributes"
      },
      {
        "command": "blkid /dev/sda1",
        "explanation": "Show attributes for specific device"
      },
      {
        "command": "blkid -s UUID",
        "explanation": "Show only UUIDs"
      }
    ],
    "tips": [
      "Use for finding UUIDs for /etc/fstab",
      "May require sudo for some devices",
      "Shows filesystem type and labels"
    ]
  },
  
  "parted": {
    "description": "Partition editor - create, resize, and manage partitions",
    "usage": "parted [OPTIONS] [DEVICE]",
    "category": "disk_management",
    "tags": ["partition", "disk", "resize", "gpt", "management"],
    "common_options": {
      "-l": "List partition layouts",
      "-s": "Script mode (non-interactive)"
    },
    "examples": [
      {
        "command": "sudo parted -l",
        "explanation": "List all partition tables"
      },
      {
        "command": "sudo parted /dev/sda print",
        "explanation": "Show partitions on /dev/sda"
      }
    ],
    "tips": [
      "Supports both MBR and GPT partition tables",
      "Can resize partitions (use carefully!)",
      "Always requires root privileges"
    ]
  },
  
  "mkfs": {
    "description": "Make filesystem - format partitions with specific filesystem",
    "usage": "mkfs.TYPE [OPTIONS] DEVICE",
    "category": "disk_management",
    "tags": ["format", "filesystem", "partition", "create"],
    "filesystem_types": {
      "ext4": "Standard Linux filesystem",
      "ext3": "Older ext version",
      "xfs": "High-performance filesystem",
      "btrfs": "Modern copy-on-write filesystem",
      "vfat": "FAT32 for USB drives"
    },
    "examples": [
      {
        "command": "sudo mkfs.ext4 /dev/sdb1",
        "explanation": "Format partition as ext4"
      },
      {
        "command": "sudo mkfs.vfat /dev/sdc1",
        "explanation": "Format as FAT32 (for USB)"
      },
      {
        "command": "sudo mkfs.ext4 -L MyDrive /dev/sdb1",
        "explanation": "Format with label 'MyDrive'"
      }
    ],
    "tips": [
      "⚠️ DESTROYS ALL DATA on the partition!",
      "Always double-check device name",
      "Use lsblk to identify correct device first"
    ]
  },
  
  "sysctl": {
    "description": "Configure kernel parameters at runtime",
    "usage": "sysctl [OPTIONS] [VARIABLE[=VALUE]]",
    "category": "system_info",
    "tags": ["kernel", "tuning", "parameter", "configuration"],
    "common_options": {
      "-a": "Display all values",
      "-w": "Write/set a value",
      "-p": "Load values from file"
    },
    "examples": [
      {
        "command": "sysctl -a",
        "explanation": "Show all kernel parameters"
      },
      {
        "command": "sysctl vm.swappiness",
        "explanation": "Show swappiness value"
      },
      {
        "command": "sudo sysctl -w vm.swappiness=10",
        "explanation": "Set swappiness to 10"
      }
    ],
    "tips": [
      "Changes are temporary unless added to /etc/sysctl.conf",
      "Common tuning: net.ipv4.ip_forward, vm.swappiness",
      "Reload config: sysctl -p"
    ]
  },
  
  "lscpu": {
    "description": "Display CPU architecture information",
    "usage": "lscpu [OPTIONS]",
    "category": "system_info",
    "tags": ["cpu", "processor", "hardware", "architecture"],
    "common_options": {
      "-e": "Extended readable format",
      "-p": "Parsable format",
      "-J": "JSON output"
    },
    "examples": [
      {
        "command": "lscpu",
        "explanation": "Show CPU architecture details"
      },
      {
        "command": "lscpu | grep -i mhz",
        "explanation": "Show CPU frequency"
      },
      {
        "command": "lscpu -J",
        "explanation": "Output in JSON format"
      }
    ],
    "tips": [
      "Shows cores, threads, cache sizes",
      "Useful for capacity planning",
      "Part of util-linux package"
    ]
  },
  
  "dmidecode": {
    "description": "DMI/SMBIOS table decoder - hardware information",
    "usage": "dmidecode [OPTIONS]",
    "category": "system_info",
    "tags": ["hardware", "bios", "system", "dmi"],
    "common_options": {
      "-t": "Type (bios, system, baseboard, processor, memory)",
      "-s": "String (system-serial-number, system-uuid, etc.)",
      "-q": "Less verbose output"
    },
    "examples": [
      {
        "command": "sudo dmidecode -t memory",
        "explanation": "Show memory information"
      },
      {
        "command": "sudo dmidecode -t processor",
        "explanation": "Show CPU information"
      },
      {
        "command": "sudo dmidecode -s system-serial-number",
        "explanation": "Show system serial number"
      }
    ],
    "tips": [
      "Requires root privileges",
      "Useful for hardware inventory",
      "Works on x86/x86_64 systems with SMBIOS"
    ]
  },
  
  "lshw": {
    "description": "List hardware configuration",
    "usage": "lshw [OPTIONS]",
    "category": "system_info",
    "tags": ["hardware", "system", "devices"],
    "common_options": {
      "-short": "Short format output",
      "-html": "HTML output format",
      "-class": "Show specific hardware class"
    },
    "examples": [
      {
        "command": "sudo lshw -short",
        "explanation": "Show hardware summary"
      },
      {
        "command": "sudo lshw -class disk",
        "explanation": "Show disk information"
      },
      {
        "command": "sudo lshw -class network",
        "explanation": "Show network devices"
      }
    ],
    "tips": [
      "Requires root for complete information",
      "Can output in various formats (xml, json, html)",
      "Install: apt install lshw or yum install lshw"
    ]
  },
  
  "resize2fs": {
    "description": "Resize ext2/ext3/ext4 file systems",
    "usage": "resize2fs DEVICE [SIZE]",
    "category": "disk_management",
    "tags": ["filesystem", "resize", "ext4", "partition"],
    "common_options": {
      "-p": "Print progress bar",
      "-f": "Force resize",
      "-M": "Shrink to minimum size"
    },
    "examples": [
      {
        "command": "sudo resize2fs /dev/sda1",
        "explanation": "Resize to fill available space"
      },
      {
        "command": "sudo resize2fs /dev/sda1 10G",
        "explanation": "Resize to 10GB"
      },
      {
        "command": "sudo resize2fs -M /dev/sda1",
        "explanation": "Shrink to minimum size"
      }
    ],
    "tips": [
      "Run fsck before shrinking",
      "Unmount filesystem before shrinking",
      "Can expand online (while mounted)"
    ]
  },
  
  "tune2fs": {
    "description": "Adjust tunable filesystem parameters on ext2/ext3/ext4",
    "usage": "tune2fs [OPTIONS] DEVICE",
    "category": "disk_management",
    "tags": ["filesystem", "tuning", "ext4", "parameters"],
    "common_options": {
      "-l": "List filesystem parameters",
      "-L": "Set volume label",
      "-c": "Set mount count check interval",
      "-m": "Set reserved blocks percentage"
    },
    "examples": [
      {
        "command": "sudo tune2fs -l /dev/sda1",
        "explanation": "Show filesystem info"
      },
      {
        "command": "sudo tune2fs -L MyDisk /dev/sda1",
        "explanation": "Set volume label"
      },
      {
        "command": "sudo tune2fs -m 1 /dev/sda1",
        "explanation": "Set 1% reserved blocks"
      }
    ],
    "tips": [
      "Can modify mounted filesystem safely",
      "Check mount count: tune2fs -l | grep Mount",
      "Disable fsck count check: tune2fs -c 0"
    ]
  },
  
  "dumpe2fs": {
    "description": "Dump ext2/ext3/ext4 filesystem information",
    "usage": "dumpe2fs [OPTIONS] DEVICE",
    "category": "disk_management",
    "tags": ["filesystem", "info", "ext4", "diagnostic"],
    "common_options": {
      "-h": "Only show superblock information",
      "-b": "Show reserved blocks",
      "-f": "Force display even if errors"
    },
    "examples": [
      {
        "command": "sudo dumpe2fs /dev/sda1 | grep -i block",
        "explanation": "Show block information"
      },
      {
        "command": "sudo dumpe2fs -h /dev/sda1",
        "explanation": "Show superblock only"
      }
    ],
    "tips": [
      "Useful for filesystem troubleshooting",
      "Shows detailed inode and block info",
      "Combine with grep for specific data"
    ]
  },
  
  "pstree": {
    "description": "Display processes in tree format",
    "usage": "pstree [OPTIONS] [PID|USER]",
    "category": "process_management",
    "tags": ["process", "tree", "hierarchy", "parent"],
    "common_options": {
      "-p": "Show PIDs",
      "-a": "Show command line arguments",
      "-u": "Show user transitions",
      "-h": "Highlight current process"
    },
    "examples": [
      {
        "command": "pstree",
        "explanation": "Show all processes in tree"
      },
      {
        "command": "pstree -p",
        "explanation": "Show with PIDs"
      },
      {
        "command": "pstree username",
        "explanation": "Show processes for specific user"
      }
    ],
    "tips": [
      "Great for understanding process relationships",
      "Use with -p to see PIDs for killing",
      "Install: apt install psmisc"
    ]
  },
  
  "pidstat": {
    "description": "Report statistics for Linux tasks (processes)",
    "usage": "pidstat [OPTIONS] [INTERVAL] [COUNT]",
    "category": "process_management",
    "tags": ["process", "statistics", "performance", "monitor"],
    "common_options": {
      "-u": "CPU statistics",
      "-r": "Memory statistics",
      "-d": "I/O statistics",
      "-p": "Monitor specific PID"
    },
    "examples": [
      {
        "command": "pidstat 1 5",
        "explanation": "CPU stats every 1 sec, 5 times"
      },
      {
        "command": "pidstat -r 2",
        "explanation": "Memory stats every 2 seconds"
      },
      {
        "command": "pidstat -p 1234",
        "explanation": "Stats for specific process"
      }
    ],
    "tips": [
      "Part of sysstat package",
      "Use -d for disk I/O per process",
      "Combine with -h for human-readable"
    ]
  },
  
  "sar": {
    "description": "Collect, report, or save system activity information",
    "usage": "sar [OPTIONS] [INTERVAL] [COUNT]",
    "category": "system_info",
    "tags": ["performance", "monitoring", "statistics", "cpu", "memory"],
    "common_options": {
      "-u": "CPU utilization",
      "-r": "Memory utilization",
      "-n": "Network statistics",
      "-d": "Disk activity",
      "-q": "Queue length and load averages"
    },
    "examples": [
      {
        "command": "sar -u 1 5",
        "explanation": "CPU usage every 1 sec, 5 times"
      },
      {
        "command": "sar -r 2 3",
        "explanation": "Memory stats every 2 secs, 3 times"
      },
      {
        "command": "sar -n DEV 1 5",
        "explanation": "Network interface stats"
      }
    ],
    "tips": [
      "Part of sysstat package",
      "Logs to /var/log/sa/ directory",
      "View historical data: sar -f /var/log/sa/sa10"
    ]
  },
  
  "htop": {
    "description": "Interactive process viewer (improved top)",
    "usage": "htop [OPTIONS]",
    "category": "process_management",
    "tags": ["process", "monitor", "interactive", "cpu", "memory"],
    "common_options": {
      "-u": "Show only user's processes",
      "-p": "Show only given PIDs",
      "-s": "Sort by column",
      "-t": "Tree view"
    },
    "examples": [
      {
        "command": "htop",
        "explanation": "Launch interactive monitor"
      },
      {
        "command": "htop -u username",
        "explanation": "Show only user's processes"
      },
      {
        "command": "htop -t",
        "explanation": "Start in tree view mode"
      }
    ],
    "tips": [
      "F9 to kill processes, F6 to sort",
      "Space to tag, U to untag all",
      "Install: apt install htop"
    ]
  },
  
  "swapon": {
    "description": "Enable swap space",
    "usage": "swapon [OPTIONS] [DEVICE]",
    "category": "system_info",
    "tags": ["swap", "memory", "paging"],
    "common_options": {
      "-s": "Display swap usage summary",
      "-a": "Enable all swaps in /etc/fstab",
      "-p": "Set priority"
    },
    "examples": [
      {
        "command": "swapon -s",
        "explanation": "Show swap usage"
      },
      {
        "command": "sudo swapon /dev/sdb1",
        "explanation": "Enable swap on device"
      },
      {
        "command": "sudo swapon -a",
        "explanation": "Enable all swaps from fstab"
      }
    ],
    "tips": [
      "Check swap: swapon -s or free -h",
      "Set priority with -p for multiple swaps",
      "Add to /etc/fstab for permanent"
    ]
  },
  
  "mkswap": {
    "description": "Set up a Linux swap area",
    "usage": "mkswap [OPTIONS] DEVICE",
    "category": "system_info",
    "tags": ["swap", "create", "memory", "partition"],
    "common_options": {
      "-L": "Set label",
      "-U": "Set UUID",
      "-c": "Check for bad blocks"
    },
    "examples": [
      {
        "command": "sudo mkswap /dev/sdb1",
        "explanation": "Create swap on partition"
      },
      {
        "command": "sudo mkswap -L myswap /dev/sdb1",
        "explanation": "Create swap with label"
      }
    ],
    "tips": [
      "Run mkswap before swapon",
      "⚠️ Destroys data on partition",
      "Follow with: swapon /dev/sdb1"
    ]
  },
  
  "swapoff": {
    "description": "Disable swap space",
    "usage": "swapoff [OPTIONS] [DEVICE]",
    "category": "system_info",
    "tags": ["swap", "memory", "disable"],
    "common_options": {
      "-a": "Disable all swaps",
      "-v": "Verbose output"
    },
    "examples": [
      {
        "command": "sudo swapoff /dev/sdb1",
        "explanation": "Disable specific swap"
      },
      {
        "command": "sudo swapoff -a",
        "explanation": "Disable all swap spaces"
      }
    ],
    "tips": [
      "Use before removing swap device",
      "May take time if swap is in use",
      "Check with: free -h"
    ]
  },
  
  "useradd": {
    "description": "Create a new user account",
    "usage": "useradd [OPTIONS] USERNAME",
    "category": "user_management",
    "tags": ["user", "create", "account", "admin"],
    "common_options": {
      "-m": "Create home directory",
      "-s": "Set login shell",
      "-G": "Add to supplementary groups",
      "-u": "Set specific UID",
      "-c": "Add comment (full name)"
    },
    "examples": [
      {
        "command": "sudo useradd -m john",
        "explanation": "Create user with home directory"
      },
      {
        "command": "sudo useradd -m -s /bin/bash -G sudo john",
        "explanation": "Create user with bash shell and sudo access"
      },
      {
        "command": "sudo useradd -m -c \"John Doe\" john",
        "explanation": "Create user with full name"
      }
    ],
    "tips": [
      "Set password: passwd username",
      "Use -m to auto-create home directory",
      "Default shell is usually /bin/sh"
    ]
  },
  
  "userdel": {
    "description": "Delete a user account",
    "usage": "userdel [OPTIONS] USERNAME",
    "category": "user_management",
    "tags": ["user", "delete", "remove", "account"],
    "common_options": {
      "-r": "Remove home directory and mail spool",
      "-f": "Force removal"
    },
    "examples": [
      {
        "command": "sudo userdel john",
        "explanation": "Delete user (keep home directory)"
      },
      {
        "command": "sudo userdel -r john",
        "explanation": "Delete user and home directory"
      }
    ],
    "tips": [
      "⚠️ Use -r to remove home directory",
      "Check for running processes first: ps -u john",
      "Backup important data before deletion"
    ]
  },
  
  "usermod": {
    "description": "Modify a user account",
    "usage": "usermod [OPTIONS] USERNAME",
    "category": "user_management",
    "tags": ["user", "modify", "edit", "account"],
    "common_options": {
      "-G": "Set supplementary groups",
      "-aG": "Append to groups",
      "-s": "Change shell",
      "-L": "Lock account",
      "-U": "Unlock account"
    },
    "examples": [
      {
        "command": "sudo usermod -aG sudo john",
        "explanation": "Add user to sudo group"
      },
      {
        "command": "sudo usermod -s /bin/zsh john",
        "explanation": "Change user's shell"
      },
      {
        "command": "sudo usermod -L john",
        "explanation": "Lock user account"
      }
    ],
    "tips": [
      "Use -aG to append groups (not replace)",
      "Lock account instead of deleting",
      "Changes take effect on next login"
    ]
  },
  
  "id": {
    "description": "Print user and group information",
    "usage": "id [OPTIONS] [USERNAME]",
    "category": "user_management",
    "tags": ["user", "group", "uid", "gid"],
    "common_options": {
      "-u": "Print only UID",
      "-g": "Print only primary GID",
      "-G": "Print all GIDs",
      "-n": "Print names instead of numbers"
    },
    "examples": [
      {
        "command": "id",
        "explanation": "Show current user info"
      },
      {
        "command": "id john",
        "explanation": "Show info for specific user"
      },
      {
        "command": "id -u john",
        "explanation": "Show only UID"
      }
    ],
    "tips": [
      "Useful for checking group membership",
      "Combine with -n for readable output",
      "Check sudo access: id -nG | grep -w sudo"
    ]
  },
  
  "su": {
    "description": "Switch user - run command as another user",
    "usage": "su [OPTIONS] [USERNAME]",
    "category": "user_management",
    "tags": ["user", "switch", "sudo", "root"],
    "common_options": {
      "-": "Start login shell (load user's environment)",
      "-c": "Run specific command",
      "-s": "Specify shell"
    },
    "examples": [
      {
        "command": "su -",
        "explanation": "Switch to root with full environment"
      },
      {
        "command": "su - john",
        "explanation": "Switch to john's account"
      },
      {
        "command": "su -c 'systemctl restart nginx' root",
        "explanation": "Run command as root"
      }
    ],
    "tips": [
      "Use 'su -' for full environment",
      "Prefer sudo over su when possible",
      "Exit with 'exit' or Ctrl+D"
    ]
  },
  
  "ethtool": {
    "description": "Query or control network driver and hardware settings",
    "usage": "ethtool [OPTIONS] DEVICE",
    "category": "network",
    "tags": ["network", "interface", "ethernet", "speed"],
    "common_options": {
      "-i": "Show driver information",
      "-S": "Show statistics",
      "-s": "Change settings",
      "-k": "Show offload features"
    },
    "examples": [
      {
        "command": "ethtool eth0",
        "explanation": "Show interface settings"
      },
      {
        "command": "ethtool -S eth0",
        "explanation": "Show interface statistics"
      },
      {
        "command": "ethtool -i eth0",
        "explanation": "Show driver information"
      }
    ],
    "tips": [
      "Check link speed and duplex",
      "Useful for troubleshooting connectivity",
      "Requires root for changes"
    ]
  },
  
  "ip": {
    "description": "Show/manipulate routing, devices, policy routing and tunnels",
    "usage": "ip [OPTIONS] OBJECT COMMAND",
    "category": "network",
    "tags": ["network", "routing", "interface", "address"],
    "common_options": {
      "addr": "Manage IP addresses",
      "link": "Manage network devices",
      "route": "Manage routing table",
      "-c": "Use color output"
    },
    "examples": [
      {
        "command": "ip addr show",
        "explanation": "Show all IP addresses"
      },
      {
        "command": "ip link set eth0 up",
        "explanation": "Bring interface up"
      },
      {
        "command": "ip route show",
        "explanation": "Show routing table"
      },
      {
        "command": "ip addr add 192.168.1.10/24 dev eth0",
        "explanation": "Add IP address to interface"
      }
    ],
    "tips": [
      "Modern replacement for ifconfig",
      "Use 'ip -c' for colored output",
      "ip addr = ip a (shorthand)"
    ]
  },
  
  "less": {
    "description": "View file contents with forward and backward navigation",
    "usage": "less [OPTIONS] FILE",
    "category": "file_operations",
    "tags": ["view", "pager", "read", "scroll"],
    "common_options": {
      "-N": "Show line numbers",
      "-S": "Chop long lines",
      "-i": "Case-insensitive search",
      "+F": "Follow mode (like tail -f)"
    },
    "examples": [
      {
        "command": "less file.txt",
        "explanation": "View file with navigation"
      },
      {
        "command": "less -N file.txt",
        "explanation": "View with line numbers"
      },
      {
        "command": "less +F /var/log/syslog",
        "explanation": "Follow log file in real-time"
      }
    ],
    "tips": [
      "Press / to search, n for next match",
      "Press q to quit, Space for next page",
      "Press G to go to end, g for beginning"
    ]
  },
  
  "yum": {
    "description": "Package manager for RPM-based distributions (RHEL, CentOS, Fedora)",
    "usage": "yum [OPTIONS] COMMAND [PACKAGE]",
    "category": "package_management",
    "tags": ["package", "install", "rpm", "yum", "redhat"],
    "common_options": {
      "install": "Install package",
      "remove": "Remove package",
      "update": "Update packages",
      "search": "Search for package",
      "info": "Show package info"
    },
    "examples": [
      {
        "command": "sudo yum install nginx",
        "explanation": "Install nginx package"
      },
      {
        "command": "sudo yum update",
        "explanation": "Update all packages"
      },
      {
        "command": "yum search python",
        "explanation": "Search for python packages"
      },
      {
        "command": "sudo yum remove package",
        "explanation": "Remove package"
      }
    ],
    "tips": [
      "Use -y flag to auto-confirm",
      "yum history for transaction history",
      "dnf is the newer yum replacement"
    ]
  },
  
  "rpm": {
    "description": "RPM Package Manager - query and manage RPM packages",
    "usage": "rpm [OPTIONS] [PACKAGE]",
    "category": "package_management",
    "tags": ["package", "rpm", "query", "install"],
    "common_options": {
      "-qa": "Query all packages",
      "-qi": "Query package info",
      "-ql": "List files in package",
      "-qf": "Find package owning file",
      "-ivh": "Install with verbose and hash marks"
    },
    "examples": [
      {
        "command": "rpm -qa",
        "explanation": "List all installed packages"
      },
      {
        "command": "rpm -qi package",
        "explanation": "Show package information"
      },
      {
        "command": "rpm -ql package",
        "explanation": "List files in package"
      },
      {
        "command": "rpm -qf /usr/bin/ls",
        "explanation": "Find which package owns file"
      }
    ],
    "tips": [
      "Use with grep: rpm -qa | grep python",
      "Verify package: rpm -V package",
      "Prefer yum/dnf over direct rpm"
    ]
  },
  
  "apt-get": {
    "description": "APT package handling utility for Debian/Ubuntu",
    "usage": "apt-get [OPTIONS] COMMAND [PACKAGE]",
    "category": "package_management",
    "tags": ["package", "install", "debian", "ubuntu", "apt"],
    "common_options": {
      "install": "Install package",
      "remove": "Remove package",
      "update": "Update package lists",
      "upgrade": "Upgrade packages",
      "autoremove": "Remove unused packages"
    },
    "examples": [
      {
        "command": "sudo apt-get update",
        "explanation": "Update package lists"
      },
      {
        "command": "sudo apt-get install nginx",
        "explanation": "Install nginx package"
      },
      {
        "command": "sudo apt-get upgrade",
        "explanation": "Upgrade all packages"
      },
      {
        "command": "sudo apt-get autoremove",
        "explanation": "Remove unused dependencies"
      }
    ],
    "tips": [
      "Always update before install",
      "Use apt instead of apt-get (newer)",
      "apt search for finding packages"
    ]
  },
  
  "dpkg": {
    "description": "Debian package manager - low-level package tool",
    "usage": "dpkg [OPTIONS] [PACKAGE.deb]",
    "category": "package_management",
    "tags": ["package", "debian", "ubuntu", "deb"],
    "common_options": {
      "-i": "Install package",
      "-r": "Remove package",
      "-l": "List packages",
      "-L": "List files in package",
      "-S": "Find package owning file"
    },
    "examples": [
      {
        "command": "dpkg -l",
        "explanation": "List all installed packages"
      },
      {
        "command": "sudo dpkg -i package.deb",
        "explanation": "Install .deb package"
      },
      {
        "command": "dpkg -L package",
        "explanation": "List files in package"
      },
      {
        "command": "dpkg -S /usr/bin/ls",
        "explanation": "Find which package owns file"
      }
    ],
    "tips": [
      "Use with grep: dpkg -l | grep python",
      "Prefer apt-get over direct dpkg",
      "Fix broken: dpkg --configure -a"
    ]
  },
  
  "vgs": {
    "description": "Display volume group information (LVM)",
    "usage": "vgs [OPTIONS] [VG_NAME]",
    "category": "disk_management",
    "tags": ["lvm", "volume", "storage", "vg"],
    "common_options": {
      "-o": "Specify output columns",
      "-a": "Show all information",
      "-v": "Verbose output"
    },
    "examples": [
      {
        "command": "vgs",
        "explanation": "List all volume groups"
      },
      {
        "command": "vgs -o +pv_count",
        "explanation": "Show with PV count column"
      }
    ],
    "tips": [
      "Part of LVM2 package",
      "Shows VG size, free space, PV count",
      "Use vgdisplay for detailed info"
    ]
  },
  
  "vgcreate": {
    "description": "Create a volume group (LVM)",
    "usage": "vgcreate [OPTIONS] VG_NAME PV_PATH",
    "category": "disk_management",
    "tags": ["lvm", "volume", "create", "storage"],
    "common_options": {
      "-s": "Set physical extent size",
      "-l": "Set maximum logical volumes",
      "-p": "Set maximum physical volumes"
    },
    "examples": [
      {
        "command": "sudo vgcreate vg01 /dev/sdb",
        "explanation": "Create volume group from disk"
      },
      {
        "command": "sudo vgcreate vg01 /dev/sdb /dev/sdc",
        "explanation": "Create VG from multiple disks"
      }
    ],
    "tips": [
      "Initialize PV first: pvcreate /dev/sdb",
      "Default extent size is 4MB",
      "Use descriptive VG names"
    ]
  },
  
  "vgextend": {
    "description": "Extend a volume group by adding physical volumes",
    "usage": "vgextend VG_NAME PV_PATH",
    "category": "disk_management",
    "tags": ["lvm", "volume", "extend", "storage"],
    "examples": [
      {
        "command": "sudo vgextend vg01 /dev/sdc",
        "explanation": "Add physical volume to VG"
      }
    ],
    "tips": [
      "PV must be initialized first",
      "Check space: vgs after extending",
      "Can add multiple PVs at once"
    ]
  },
  
  "vgreduce": {
    "description": "Reduce a volume group by removing physical volumes",
    "usage": "vgreduce VG_NAME PV_PATH",
    "category": "disk_management",
    "tags": ["lvm", "volume", "reduce", "storage"],
    "examples": [
      {
        "command": "sudo vgreduce vg01 /dev/sdc",
        "explanation": "Remove PV from VG"
      }
    ],
    "tips": [
      "Move data off PV first: pvmove",
      "Cannot remove if space needed",
      "Use --removemissing for failed disks"
    ]
  },
  
  "vgremove": {
    "description": "Remove a volume group",
    "usage": "vgremove VG_NAME",
    "category": "disk_management",
    "tags": ["lvm", "volume", "remove", "delete"],
    "examples": [
      {
        "command": "sudo vgremove vg01",
        "explanation": "Remove volume group"
      }
    ],
    "tips": [
      "Remove all LVs first",
      "⚠️ Destroys all data in VG",
      "Deactivate first: vgchange -an vg01"
    ]
  },
  
  "vgdisplay": {
    "description": "Display volume group information in detail",
    "usage": "vgdisplay [VG_NAME]",
    "category": "disk_management",
    "tags": ["lvm", "volume", "info", "display"],
    "examples": [
      {
        "command": "sudo vgdisplay",
        "explanation": "Show all VG details"
      },
      {
        "command": "sudo vgdisplay vg01",
        "explanation": "Show specific VG details"
      }
    ],
    "tips": [
      "Shows total/free extents",
      "Use vgs for quick summary",
      "Check PE size and count"
    ]
  },
  
  "vgscan": {
    "description": "Scan disks for volume groups",
    "usage": "vgscan [OPTIONS]",
    "category": "disk_management",
    "tags": ["lvm", "volume", "scan", "detect"],
    "examples": [
      {
        "command": "sudo vgscan",
        "explanation": "Scan and rebuild VG cache"
      }
    ],
    "tips": [
      "Run after adding new disks",
      "Rebuilds /etc/lvm/cache",
      "Useful for recovery"
    ]
  },
  
  "lvs": {
    "description": "Display logical volume information (LVM)",
    "usage": "lvs [OPTIONS] [LV_PATH]",
    "category": "disk_management",
    "tags": ["lvm", "logical", "volume", "lv"],
    "common_options": {
      "-o": "Specify output columns",
      "-a": "Show all LVs",
      "-v": "Verbose output"
    },
    "examples": [
      {
        "command": "lvs",
        "explanation": "List all logical volumes"
      },
      {
        "command": "lvs -o +devices",
        "explanation": "Show with underlying devices"
      }
    ],
    "tips": [
      "Shows LV size, VG, attributes",
      "Use lvdisplay for detailed info",
      "Check LV status with -a flag"
    ]
  },
  
  "lvcreate": {
    "description": "Create a logical volume (LVM)",
    "usage": "lvcreate [OPTIONS] VG_NAME",
    "category": "disk_management",
    "tags": ["lvm", "logical", "create", "volume"],
    "common_options": {
      "-L": "Size (e.g., 5G)",
      "-l": "Size in extents",
      "-n": "LV name",
      "-s": "Create snapshot"
    },
    "examples": [
      {
        "command": "sudo lvcreate -L 5G -n lv01 vg01",
        "explanation": "Create 5GB logical volume"
      },
      {
        "command": "sudo lvcreate -l 100%FREE -n lv01 vg01",
        "explanation": "Use all free space"
      },
      {
        "command": "sudo lvcreate -L 1G -s -n snap01 /dev/vg01/lv01",
        "explanation": "Create snapshot"
      }
    ],
    "tips": [
      "Create filesystem after: mkfs.ext4",
      "Use descriptive LV names",
      "Check space: vgs before creating"
    ]
  },
  
  "lvextend": {
    "description": "Extend a logical volume",
    "usage": "lvextend [OPTIONS] LV_PATH",
    "category": "disk_management",
    "tags": ["lvm", "logical", "extend", "resize"],
    "common_options": {
      "-L": "New size or +size",
      "-l": "Size in extents",
      "-r": "Resize filesystem too"
    },
    "examples": [
      {
        "command": "sudo lvextend -L +2G /dev/vg01/lv01",
        "explanation": "Extend by 2GB"
      },
      {
        "command": "sudo lvextend -L 10G /dev/vg01/lv01",
        "explanation": "Extend to 10GB total"
      },
      {
        "command": "sudo lvextend -r -l +100%FREE /dev/vg01/lv01",
        "explanation": "Extend to use all free space and resize FS"
      }
    ],
    "tips": [
      "Use -r to auto-resize filesystem",
      "Or resize manually: resize2fs",
      "Can extend online (mounted)"
    ]
  },
  
  "lvreduce": {
    "description": "Reduce a logical volume",
    "usage": "lvreduce [OPTIONS] LV_PATH",
    "category": "disk_management",
    "tags": ["lvm", "logical", "reduce", "shrink"],
    "common_options": {
      "-L": "New size or -size",
      "-r": "Resize filesystem too"
    },
    "examples": [
      {
        "command": "sudo lvreduce -L -1G /dev/vg01/lv01",
        "explanation": "Reduce by 1GB"
      },
      {
        "command": "sudo lvreduce -L 5G /dev/vg01/lv01",
        "explanation": "Reduce to 5GB total"
      }
    ],
    "tips": [
      "⚠️ Shrink filesystem first!",
      "Unmount before shrinking",
      "Backup data before reducing"
    ]
  },
  
  "lvremove": {
    "description": "Remove a logical volume",
    "usage": "lvremove LV_PATH",
    "category": "disk_management",
    "tags": ["lvm", "logical", "remove", "delete"],
    "examples": [
      {
        "command": "sudo lvremove /dev/vg01/lv01",
        "explanation": "Remove logical volume"
      }
    ],
    "tips": [
      "⚠️ Destroys all data",
      "Unmount first",
      "Use -f to force without confirmation"
    ]
  },
  
  "lvdisplay": {
    "description": "Display logical volume information in detail",
    "usage": "lvdisplay [LV_PATH]",
    "category": "disk_management",
    "tags": ["lvm", "logical", "info", "display"],
    "examples": [
      {
        "command": "sudo lvdisplay",
        "explanation": "Show all LV details"
      },
      {
        "command": "sudo lvdisplay /dev/vg01/lv01",
        "explanation": "Show specific LV details"
      }
    ],
    "tips": [
      "Shows size, segments, status",
      "Use lvs for quick summary",
      "Check LV path and size"
    ]
  },
  
  "lspci": {
    "description": "List all PCI devices",
    "usage": "lspci [OPTIONS]",
    "category": "system_info",
    "tags": ["hardware", "pci", "devices"],
    "common_options": {
      "-v": "Verbose output",
      "-vv": "Very verbose",
      "-k": "Show kernel drivers",
      "-t": "Tree format"
    },
    "examples": [
      {
        "command": "lspci",
        "explanation": "List all PCI devices"
      },
      {
        "command": "lspci -v",
        "explanation": "Verbose device information"
      },
      {
        "command": "lspci -k | grep -A 3 VGA",
        "explanation": "Show graphics card and driver"
      }
    ],
    "tips": [
      "Useful for hardware identification",
      "Check driver: lspci -k",
      "Install: apt install pciutils"
    ]
  },
  
  "lsusb": {
    "description": "List USB devices",
    "usage": "lsusb [OPTIONS]",
    "category": "system_info",
    "tags": ["hardware", "usb", "devices"],
    "common_options": {
      "-v": "Verbose output",
      "-t": "Tree format",
      "-s": "Show specific device"
    },
    "examples": [
      {
        "command": "lsusb",
        "explanation": "List all USB devices"
      },
      {
        "command": "lsusb -v",
        "explanation": "Verbose device information"
      },
      {
        "command": "lsusb -t",
        "explanation": "Show USB device tree"
      }
    ],
    "tips": [
      "Shows vendor and product IDs",
      "Useful for troubleshooting USB",
      "Install: apt install usbutils"
    ]
  },
  
  "hdparm": {
    "description": "Get/set SATA/IDE device parameters",
    "usage": "hdparm [OPTIONS] DEVICE",
    "category": "disk_management",
    "tags": ["disk", "performance", "sata", "benchmark"],
    "common_options": {
      "-I": "Display drive information",
      "-t": "Perform device read timings",
      "-T": "Perform cache read timings",
      "-S": "Set standby timeout"
    },
    "examples": [
      {
        "command": "sudo hdparm -I /dev/sda",
        "explanation": "Show disk information"
      },
      {
        "command": "sudo hdparm -tT /dev/sda",
        "explanation": "Test disk read speed"
      }
    ],
    "tips": [
      "Requires root privileges",
      "Use for disk benchmarking",
      "Check SMART status too"
    ]
  },
  
  "vim": {
    "description": "Vi IMproved - advanced text editor",
    "usage": "vim [OPTIONS] [FILE]",
    "category": "text_processing",
    "tags": ["editor", "text", "vi", "edit"],
    "common_options": {
      "-R": "Read-only mode",
      "-n": "No swap file",
      "+": "Start at specific line",
      "-d": "Diff mode"
    },
    "examples": [
      {
        "command": "vim file.txt",
        "explanation": "Open file for editing"
      },
      {
        "command": "vim +10 file.txt",
        "explanation": "Open at line 10"
      },
      {
        "command": "vim -d file1 file2",
        "explanation": "Compare two files"
      }
    ],
    "tips": [
      "Press i for insert mode, Esc to exit",
      ":wq to save and quit, :q! to quit without saving",
      "Learn vimtutor for basics"
    ]
  },
  
  "nano": {
    "description": "Simple, easy-to-use text editor",
    "usage": "nano [OPTIONS] [FILE]",
    "category": "text_processing",
    "tags": ["editor", "text", "simple", "beginner"],
    "common_options": {
      "-w": "Disable line wrapping",
      "-m": "Enable mouse support",
      "-l": "Show line numbers",
      "-B": "Save backups"
    },
    "examples": [
      {
        "command": "nano file.txt",
        "explanation": "Open file for editing"
      },
      {
        "command": "nano -l file.txt",
        "explanation": "Open with line numbers"
      }
    ],
    "tips": [
      "Ctrl+O to save, Ctrl+X to exit",
      "Ctrl+K cuts line, Ctrl+U pastes",
      "Commands shown at bottom"
    ]
  },
  
  "rsync": {
    "description": "Fast, versatile file copying tool for remote and local",
    "usage": "rsync [OPTIONS] SOURCE DEST",
    "category": "file_operations",
    "tags": ["sync", "copy", "backup", "remote", "transfer"],
    "common_options": {
      "-a": "Archive mode (recursive, preserves)",
      "-v": "Verbose output",
      "-z": "Compress during transfer",
      "-P": "Show progress",
      "--delete": "Delete files not in source"
    },
    "examples": [
      {
        "command": "rsync -avz /source/ /dest/",
        "explanation": "Sync local directories"
      },
      {
        "command": "rsync -avz -e ssh /local/ user@host:/remote/",
        "explanation": "Sync to remote server"
      },
      {
        "command": "rsync -avP --delete /source/ /backup/",
        "explanation": "Mirror directory (delete extras)"
      }
    ],
    "tips": [
      "Trailing slash on source matters!",
      "Use -n (dry-run) first to test",
      "Much faster than cp for large transfers"
    ]
  },
  
  "scp": {
    "description": "Secure copy - copy files between hosts over SSH",
    "usage": "scp [OPTIONS] SOURCE DEST",
    "category": "network",
    "tags": ["copy", "ssh", "transfer", "secure", "remote"],
    "common_options": {
      "-r": "Recursive (copy directories)",
      "-P": "Specify port",
      "-p": "Preserve timestamps/permissions",
      "-C": "Enable compression"
    },
    "examples": [
      {
        "command": "scp file.txt user@host:/path/",
        "explanation": "Copy file to remote"
      },
      {
        "command": "scp user@host:/path/file.txt .",
        "explanation": "Copy file from remote"
      },
      {
        "command": "scp -r directory/ user@host:/path/",
        "explanation": "Copy directory recursively"
      }
    ],
    "tips": [
      "Use rsync for better resume capability",
      "Can use wildcards: scp 'user@host:*.txt' .",
      "Specify port: scp -P 2222"
    ]
  },
  

  
  "alias": {
    "description": "Create command aliases - shortcuts",
    "usage": "alias [NAME='COMMAND']",
    "category": "shell",
    "tags": ["shell", "shortcut", "alias", "bash"],
    "common_options": {},
    "examples": [
      {
        "command": "alias",
        "explanation": "List all aliases"
      },
      {
        "command": "alias ll='ls -lah'",
        "explanation": "Create alias for detailed listing"
      },
      {
        "command": "alias update='sudo apt update && sudo apt upgrade'",
        "explanation": "Create update alias"
      }
    ],
    "tips": [
      "Add to ~/.bashrc for permanence",
      "Use unalias to remove",
      "Check if alias exists: type ll"
    ]
  },
  
  "export": {
    "description": "Set environment variables for child processes",
    "usage": "export [NAME=VALUE]",
    "category": "shell",
    "tags": ["environment", "variable", "shell", "bash"],
    "common_options": {
      "-n": "Remove export attribute",
      "-p": "List all exported variables"
    },
    "examples": [
      {
        "command": "export PATH=$PATH:/new/path",
        "explanation": "Add to PATH variable"
      },
      {
        "command": "export EDITOR=vim",
        "explanation": "Set default editor"
      },
      {
        "command": "export -p",
        "explanation": "Show all exports"
      }
    ],
    "tips": [
      "Add to ~/.bashrc for persistence",
      "Use env or printenv to view all",
      "Unset with: unset VARNAME"
    ]
  },
  
  "source": {
    "description": "Execute commands from file in current shell",
    "usage": "source FILE or . FILE",
    "category": "shell",
    "tags": ["shell", "execute", "script", "bash"],
    "common_options": {},
    "examples": [
      {
        "command": "source ~/.bashrc",
        "explanation": "Reload bash configuration"
      },
      {
        "command": ". ~/.profile",
        "explanation": "Load profile (same as source)"
      },
      {
        "command": "source /etc/environment",
        "explanation": "Load environment variables"
      }
    ],
    "tips": [
      "Changes affect current shell",
      ". is shorthand for source",
      "Use after editing config files"
    ]
  },
  
  "which": {
    "description": "Locate a command - show full path",
    "usage": "which [COMMAND]",
    "category": "system_info",
    "tags": ["command", "path", "locate", "find"],
    "common_options": {
      "-a": "Show all matches"
    },
    "examples": [
      {
        "command": "which python",
        "explanation": "Find python executable path"
      },
      {
        "command": "which -a python",
        "explanation": "Show all python in PATH"
      }
    ],
    "tips": [
      "Shows first match in $PATH",
      "Use type -a for aliases too",
      "whereis shows more info"
    ]
  },
  
  "whereis": {
    "description": "Locate binary, source, and manual page files",
    "usage": "whereis [OPTIONS] COMMAND",
    "category": "system_info",
    "tags": ["command", "locate", "find", "binary"],
    "common_options": {
      "-b": "Search only for binaries",
      "-m": "Search only for manuals",
      "-s": "Search only for sources"
    },
    "examples": [
      {
        "command": "whereis ls",
        "explanation": "Find ls binary and manual"
      },
      {
        "command": "whereis -b python",
        "explanation": "Find only python binary"
      }
    ],
    "tips": [
      "Shows binary, source, and man pages",
      "Faster than find",
      "Use which for PATH-only search"
    ]
  },
  
  "xargs": {
    "description": "Build and execute commands from standard input",
    "usage": "xargs [OPTIONS] [COMMAND]",
    "category": "text_processing",
    "tags": ["pipe", "command", "input", "batch"],
    "common_options": {
      "-n": "Max args per command",
      "-I": "Replace string",
      "-P": "Parallel execution",
      "-0": "Null-separated input",
      "-t": "Print command before executing"
    },
    "examples": [
      {
        "command": "find . -name '*.txt' | xargs grep 'pattern'",
        "explanation": "Search pattern in found files"
      },
      {
        "command": "ls *.jpg | xargs -n 1 -I {} convert {} {}.png",
        "explanation": "Convert each file"
      },
      {
        "command": "find . -name '*.log' -print0 | xargs -0 rm",
        "explanation": "Delete files safely (handles spaces)"
      }
    ],
    "tips": [
      "Use -0 with find -print0 for spaces",
      "Use -P for parallel processing",
      "Great for batch operations"
    ]
  },
  
  "tee": {
    "description": "Read from stdin and write to stdout and files",
    "usage": "tee [OPTIONS] FILE",
    "category": "file_operations",
    "tags": ["pipe", "output", "redirect", "duplicate"],
    "common_options": {
      "-a": "Append (don't overwrite)",
      "-i": "Ignore interrupt signals"
    },
    "examples": [
      {
        "command": "ls -l | tee output.txt",
        "explanation": "View and save output"
      },
      {
        "command": "command | tee -a log.txt | grep error",
        "explanation": "Log and filter simultaneously"
      },
      {
        "command": "echo 'text' | sudo tee /etc/file",
        "explanation": "Write to protected file"
      }
    ],
    "tips": [
      "Useful for viewing and logging",
      "Can output to multiple files",
      "Use with sudo for protected files"
    ]
  },
  
  "diff": {
    "description": "Compare files line by line",
    "usage": "diff [OPTIONS] FILE1 FILE2",
    "category": "file_operations",
    "tags": ["compare", "difference", "patch", "files"],
    "common_options": {
      "-u": "Unified format (better readability)",
      "-r": "Recursive (directories)",
      "-w": "Ignore whitespace",
      "-q": "Brief (only report if different)",
      "-y": "Side-by-side"
    },
    "examples": [
      {
        "command": "diff file1.txt file2.txt",
        "explanation": "Compare two files"
      },
      {
        "command": "diff -u old.txt new.txt > changes.patch",
        "explanation": "Create patch file"
      },
      {
        "command": "diff -r dir1/ dir2/",
        "explanation": "Compare directories"
      }
    ],
    "tips": [
      "Use -u for better readability",
      "Create patches for version control",
      "Use diff -q for quick check"
    ]
  },
  
  "patch": {
    "description": "Apply a diff file to original",
    "usage": "patch [OPTIONS] [ORIGINAL [PATCHFILE]]",
    "category": "file_operations",
    "tags": ["apply", "diff", "update", "changes"],
    "common_options": {
      "-p": "Strip leading directories",
      "-R": "Reverse patch",
      "-dry-run": "Test without applying"
    },
    "examples": [
      {
        "command": "patch < changes.patch",
        "explanation": "Apply patch file"
      },
      {
        "command": "patch -p1 < file.patch",
        "explanation": "Apply with directory stripping"
      },
      {
        "command": "patch --dry-run < changes.patch",
        "explanation": "Test patch application"
      }
    ],
    "tips": [
      "Use --dry-run first to test",
      "Create patches with diff -u",
      "Use -R to reverse changes"
    ]
  },
  
  "watch": {
    "description": "Execute program periodically, showing output fullscreen",
    "usage": "watch [OPTIONS] COMMAND",
    "category": "system_info",
    "tags": ["monitor", "periodic", "repeat", "observe"],
    "common_options": {
      "-n": "Interval in seconds",
      "-d": "Highlight differences",
      "-t": "No title",
      "-b": "Beep on error"
    },
    "examples": [
      {
        "command": "watch df -h",
        "explanation": "Monitor disk space every 2 seconds"
      },
      {
        "command": "watch -n 5 ls -l",
        "explanation": "Check directory every 5 seconds"
      },
      {
        "command": "watch -d 'ps aux | grep nginx'",
        "explanation": "Monitor nginx processes, highlight changes"
      }
    ],
    "tips": [
      "Press Ctrl+C to exit",
      "Default interval is 2 seconds",
      "Use -d to see what changed"
    ]
  },
  
  "nmap": {
    "description": "Network exploration tool and security scanner",
    "usage": "nmap [OPTIONS] HOST",
    "category": "network",
    "tags": ["scan", "port", "security", "network", "discovery"],
    "common_options": {
      "-sS": "TCP SYN scan",
      "-sV": "Version detection",
      "-p": "Specify ports",
      "-A": "Aggressive scan (OS, version)",
      "-Pn": "Skip host discovery"
    },
    "examples": [
      {
        "command": "nmap 192.168.1.1",
        "explanation": "Basic port scan"
      },
      {
        "command": "nmap -sV -p 80,443 example.com",
        "explanation": "Scan specific ports with version detection"
      },
      {
        "command": "nmap -A 192.168.1.0/24",
        "explanation": "Scan entire subnet with OS detection"
      }
    ],
    "tips": [
      "Requires root for some scan types",
      "Use responsibly - may trigger IDS",
      "Great for network inventory"
    ]
  },
  
  "nc": {
    "description": "Netcat - networking Swiss Army knife",
    "usage": "nc [OPTIONS] HOST PORT",
    "category": "network",
    "tags": ["netcat", "tcp", "udp", "port", "socket"],
    "common_options": {
      "-l": "Listen mode",
      "-v": "Verbose",
      "-z": "Scan mode (no data)",
      "-u": "UDP mode",
      "-w": "Timeout"
    },
    "examples": [
      {
        "command": "nc -zv example.com 80",
        "explanation": "Check if port 80 is open"
      },
      {
        "command": "nc -l 8080",
        "explanation": "Listen on port 8080"
      },
      {
        "command": "echo 'GET / HTTP/1.0' | nc google.com 80",
        "explanation": "Simple HTTP request"
      }
    ],
    "tips": [
      "Great for port testing",
      "Can transfer files",
      "Use for debugging network issues"
    ]
  },
  
  "dig": {
    "description": "DNS lookup utility",
    "usage": "dig [@SERVER] DOMAIN [TYPE]",
    "category": "network",
    "tags": ["dns", "lookup", "query", "nameserver"],
    "common_options": {
      "+short": "Short output",
      "+trace": "Trace delegation path",
      "-x": "Reverse lookup",
      "@": "Specify DNS server"
    },
    "examples": [
      {
        "command": "dig example.com",
        "explanation": "Query A records"
      },
      {
        "command": "dig +short example.com",
        "explanation": "Show IP only"
      },
      {
        "command": "dig example.com MX",
        "explanation": "Query mail servers"
      },
      {
        "command": "dig @8.8.8.8 example.com",
        "explanation": "Use Google DNS"
      }
    ],
    "tips": [
      "Use +short for clean output",
      "Query types: A, AAAA, MX, NS, TXT",
      "More detailed than nslookup"
    ]
  },
  
  "host": {
    "description": "DNS lookup utility - simpler than dig",
    "usage": "host [OPTIONS] NAME [SERVER]",
    "category": "network",
    "tags": ["dns", "lookup", "simple", "query"],
    "common_options": {
      "-t": "Query type",
      "-a": "All records",
      "-v": "Verbose"
    },
    "examples": [
      {
        "command": "host example.com",
        "explanation": "Simple DNS lookup"
      },
      {
        "command": "host -t MX example.com",
        "explanation": "Query mail servers"
      },
      {
        "command": "host 8.8.8.8",
        "explanation": "Reverse DNS lookup"
      }
    ],
    "tips": [
      "Simpler than dig",
      "Good for quick lookups",
      "Supports IPv6"
    ]
  },
  
  "nslookup": {
    "description": "Query Internet name servers interactively",
    "usage": "nslookup [HOST] [SERVER]",
    "category": "network",
    "tags": ["dns", "lookup", "query", "interactive"],
    "common_options": {},
    "examples": [
      {
        "command": "nslookup example.com",
        "explanation": "Basic DNS query"
      },
      {
        "command": "nslookup example.com 8.8.8.8",
        "explanation": "Query specific DNS server"
      },
      {
        "command": "nslookup",
        "explanation": "Interactive mode"
      }
    ],
    "tips": [
      "Can run interactively",
      "dig is more powerful",
      "Set type for specific records"
    ]
  },
  
  "whois": {
    "description": "Query domain registration information",
    "usage": "whois DOMAIN",
    "category": "network",
    "tags": ["domain", "registration", "info", "lookup"],
    "common_options": {
      "-H": "Hide legal disclaimers"
    },
    "examples": [
      {
        "command": "whois example.com",
        "explanation": "Domain registration info"
      },
      {
        "command": "whois -H example.com | grep -i name",
        "explanation": "Find registrant name"
      }
    ],
    "tips": [
      "Shows registrar, dates, nameservers",
      "Use for domain investigation",
      "May be rate-limited"
    ]
  },
  
  "iptables": {
    "description": "Administration tool for IPv4 packet filtering and NAT",
    "usage": "iptables [OPTIONS] CHAIN RULE",
    "category": "network",
    "tags": ["firewall", "security", "filter", "nat"],
    "common_options": {
      "-A": "Append rule",
      "-D": "Delete rule",
      "-L": "List rules",
      "-F": "Flush rules",
      "-P": "Set policy"
    },
    "examples": [
      {
        "command": "sudo iptables -L",
        "explanation": "List all rules"
      },
      {
        "command": "sudo iptables -A INPUT -p tcp --dport 22 -j ACCEPT",
        "explanation": "Allow SSH port"
      },
      {
        "command": "sudo iptables -F",
        "explanation": "Flush all rules"
      }
    ],
    "tips": [
      "⚠️ Can lock you out of remote systems!",
      "Save rules: iptables-save",
      "Use ufw for simpler firewall"
    ]
  },
  
  "ufw": {
    "description": "Uncomplicated Firewall - easy iptables frontend",
    "usage": "ufw COMMAND",
    "category": "network",
    "tags": ["firewall", "security", "simple", "iptables"],
    "common_options": {
      "enable": "Enable firewall",
      "disable": "Disable firewall",
      "status": "Show status",
      "allow": "Allow port/service",
      "deny": "Deny port/service"
    },
    "examples": [
      {
        "command": "sudo ufw enable",
        "explanation": "Enable firewall"
      },
      {
        "command": "sudo ufw allow 22",
        "explanation": "Allow SSH"
      },
      {
        "command": "sudo ufw status numbered",
        "explanation": "Show rules with numbers"
      },
      {
        "command": "sudo ufw deny from 192.168.1.100",
        "explanation": "Block specific IP"
      }
    ],
    "tips": [
      "Much simpler than iptables",
      "Enable before setting rules",
      "Check status after changes"
    ]
  },
  
  "strace": {
    "description": "Trace system calls and signals",
    "usage": "strace [OPTIONS] COMMAND",
    "category": "system_info",
    "tags": ["debug", "trace", "syscall", "troubleshoot"],
    "common_options": {
      "-p": "Attach to PID",
      "-e": "Filter syscalls",
      "-c": "Count calls",
      "-o": "Output to file",
      "-f": "Follow forks"
    },
    "examples": [
      {
        "command": "strace ls",
        "explanation": "Trace ls command"
      },
      {
        "command": "strace -p 1234",
        "explanation": "Trace running process"
      },
      {
        "command": "strace -e open,read ls",
        "explanation": "Trace only open/read calls"
      },
      {
        "command": "strace -c ls",
        "explanation": "Summary of system calls"
      }
    ],
    "tips": [
      "Great for debugging",
      "Use -e to filter noise",
      "Use ltrace for library calls"
    ]
  },
  
  "ltrace": {
    "description": "Trace library calls",
    "usage": "ltrace [OPTIONS] COMMAND",
    "category": "system_info",
    "tags": ["debug", "trace", "library", "calls"],
    "common_options": {
      "-p": "Attach to PID",
      "-c": "Count calls",
      "-o": "Output to file",
      "-S": "Show system calls too"
    },
    "examples": [
      {
        "command": "ltrace ls",
        "explanation": "Trace library calls"
      },
      {
        "command": "ltrace -c program",
        "explanation": "Count library calls"
      }
    ],
    "tips": [
      "Complements strace",
      "Shows library function calls",
      "Useful for debugging libraries"
    ]
  },
  
  "ldd": {
    "description": "Print shared library dependencies",
    "usage": "ldd [OPTIONS] FILE",
    "category": "system_info",
    "tags": ["library", "dependencies", "shared", "debug"],
    "common_options": {
      "-v": "Verbose",
      "-r": "Check relocations",
      "-u": "Show unused dependencies"
    },
    "examples": [
      {
        "command": "ldd /bin/ls",
        "explanation": "Show ls dependencies"
      },
      {
        "command": "ldd -v program",
        "explanation": "Verbose dependency info"
      }
    ],
    "tips": [
      "Useful for troubleshooting missing libraries",
      "Shows library paths",
      "⚠️ Don't run on untrusted binaries"
    ]
  },
  
  "env": {
    "description": "Run program in modified environment or print environment",
    "usage": "env [OPTIONS] [NAME=VALUE]... [COMMAND]",
    "category": "shell",
    "tags": ["environment", "variable", "shell"],
    "common_options": {
      "-i": "Start with empty environment",
      "-u": "Unset variable",
      "-": "Ignore environment"
    },
    "examples": [
      {
        "command": "env",
        "explanation": "Print all environment variables"
      },
      {
        "command": "env VAR=value command",
        "explanation": "Run command with variable set"
      },
      {
        "command": "env -i PATH=/bin ls",
        "explanation": "Run with clean environment"
      }
    ],
    "tips": [
      "Use to see all environment vars",
      "Test commands with different env",
      "Useful for debugging PATH issues"
    ]
  },
  
  "printenv": {
    "description": "Print environment variables",
    "usage": "printenv [VARIABLE]",
    "category": "shell",
    "tags": ["environment", "variable", "shell"],
    "common_options": {},
    "examples": [
      {
        "command": "printenv",
        "explanation": "Print all variables"
      },
      {
        "command": "printenv PATH",
        "explanation": "Print PATH variable"
      },
      {
        "command": "printenv | grep JAVA",
        "explanation": "Find Java-related variables"
      }
    ],
    "tips": [
      "Similar to env",
      "Can print specific variable",
      "Useful for debugging"
    ]
  },
  
  "basename": {
    "description": "Strip directory and suffix from filenames",
    "usage": "basename NAME [SUFFIX]",
    "category": "file_operations",
    "tags": ["path", "filename", "strip"],
    "common_options": {
      "-s": "Remove suffix",
      "-a": "Support multiple arguments"
    },
    "examples": [
      {
        "command": "basename /path/to/file.txt",
        "explanation": "Get filename: file.txt"
      },
      {
        "command": "basename /path/to/file.txt .txt",
        "explanation": "Get name without extension: file"
      },
      {
        "command": "basename -a /path/f1 /path/f2",
        "explanation": "Multiple files"
      }
    ],
    "tips": [
      "Useful in shell scripts",
      "Opposite of dirname",
      "Handles trailing slashes"
    ]
  },
  
  "dirname": {
    "description": "Strip last component from file name",
    "usage": "dirname NAME",
    "category": "file_operations",
    "tags": ["path", "directory", "strip"],
    "common_options": {},
    "examples": [
      {
        "command": "dirname /path/to/file.txt",
        "explanation": "Get directory: /path/to"
      },
      {
        "command": "cd $(dirname $0)",
        "explanation": "Go to script directory"
      }
    ],
    "tips": [
      "Useful in shell scripts",
      "Opposite of basename",
      "Returns path without filename"
    ]
  },
  
  "realpath": {
    "description": "Print resolved absolute file name",
    "usage": "realpath [OPTIONS] FILE",
    "category": "file_operations",
    "tags": ["path", "absolute", "resolve", "canonical"],
    "common_options": {
      "-s": "Don't expand symlinks",
      "--relative-to": "Print relative path"
    },
    "examples": [
      {
        "command": "realpath file.txt",
        "explanation": "Get absolute path"
      },
      {
        "command": "realpath ../dir",
        "explanation": "Resolve relative path"
      },
      {
        "command": "realpath symlink",
        "explanation": "Resolve symlink to target"
      }
    ],
    "tips": [
      "Resolves . and .. in paths",
      "Follows symlinks by default",
      "Useful for getting canonical paths"
    ]
  },
  
  "file": {
    "description": "Determine file type",
    "usage": "file [OPTIONS] FILE",
    "category": "file_operations",
    "tags": ["type", "identify", "format", "magic"],
    "common_options": {
      "-b": "Brief mode (no filename)",
      "-i": "MIME type",
      "-z": "Look inside compressed files"
    },
    "examples": [
      {
        "command": "file document.pdf",
        "explanation": "Identify file type"
      },
      {
        "command": "file -i file.txt",
        "explanation": "Show MIME type"
      },
      {
        "command": "file *",
        "explanation": "Check all files in directory"
      }
    ],
    "tips": [
      "Doesn't rely on file extension",
      "Checks file content/magic numbers",
      "Use -i for MIME types"
    ]
  },
  
  "stat": {
    "description": "Display file or file system status",
    "usage": "stat [OPTIONS] FILE",
    "category": "file_operations",
    "tags": ["info", "metadata", "permissions", "inode"],
    "common_options": {
      "-c": "Custom format",
      "-f": "File system status",
      "-L": "Follow symlinks"
    },
    "examples": [
      {
        "command": "stat file.txt",
        "explanation": "Show detailed file information"
      },
      {
        "command": "stat -f .",
        "explanation": "Show filesystem information"
      },
      {
        "command": "stat -c '%a %n' file",
        "explanation": "Show octal permissions and name"
      }
    ],
    "tips": [
      "More detailed than ls -l",
      "Shows inode, blocks, times",
      "Use for forensics/debugging"
    ]
  },
  
  "nice": {
    "description": "Run program with modified scheduling priority",
    "usage": "nice [OPTIONS] COMMAND",
    "category": "process_management",
    "tags": ["priority", "cpu", "schedule", "process"],
    "common_options": {
      "-n": "Niceness value (-20 to 19)"
    },
    "examples": [
      {
        "command": "nice -n 10 command",
        "explanation": "Run with lower priority"
      },
      {
        "command": "nice command",
        "explanation": "Default niceness +10"
      },
      {
        "command": "nice -n -5 command",
        "explanation": "Higher priority (requires root)"
      }
    ],
    "tips": [
      "Higher number = lower priority",
      "Default is +10",
      "Use for background tasks"
    ]
  },
  
  "renice": {
    "description": "Alter priority of running processes",
    "usage": "renice PRIORITY -p PID",
    "category": "process_management",
    "tags": ["priority", "change", "process", "cpu"],
    "common_options": {
      "-p": "Process ID",
      "-u": "User",
      "-g": "Process group"
    },
    "examples": [
      {
        "command": "renice +5 -p 1234",
        "explanation": "Lower priority of process"
      },
      {
        "command": "renice -5 -u username",
        "explanation": "Change all user's processes"
      }
    ],
    "tips": [
      "Can change running processes",
      "Non-root can only increase niceness",
      "Root can set any value"
    ]
  },
  

  
  "killall": {
    "description": "Kill processes by name",
    "usage": "killall [OPTIONS] NAME",
    "category": "process_management",
    "tags": ["signal", "terminate", "process", "name"],
    "common_options": {
      "-9": "SIGKILL (force)",
      "-i": "Interactive confirmation",
      "-u": "Kill user's processes",
      "-v": "Verbose"
    },
    "examples": [
      {
        "command": "killall firefox",
        "explanation": "Kill all firefox processes"
      },
      {
        "command": "killall -9 -u username",
        "explanation": "Force kill user's processes"
      },
      {
        "command": "killall -i nginx",
        "explanation": "Kill with confirmation"
      }
    ],
    "tips": [
      "Kills all matching processes",
      "Be careful with common names!",
      "Use -i for safety"
    ]
  },
  
  "pkill": {
    "description": "Signal processes based on name and attributes",
    "usage": "pkill [OPTIONS] PATTERN",
    "category": "process_management",
    "tags": ["signal", "terminate", "process", "pattern"],
    "common_options": {
      "-9": "SIGKILL",
      "-u": "User",
      "-f": "Match full command line",
      "-x": "Exact match"
    },
    "examples": [
      {
        "command": "pkill firefox",
        "explanation": "Kill processes matching firefox"
      },
      {
        "command": "pkill -u username",
        "explanation": "Kill user's processes"
      },
      {
        "command": "pkill -f 'python.*script.py'",
        "explanation": "Match full command line"
      }
    ],
    "tips": [
      "More flexible than killall",
      "Supports regex patterns",
      "Use pgrep to test pattern first"
    ]
  },
  
  "pgrep": {
    "description": "Look up processes based on name and attributes",
    "usage": "pgrep [OPTIONS] PATTERN",
    "category": "process_management",
    "tags": ["find", "search", "process", "pattern"],
    "common_options": {
      "-l": "List name and PID",
      "-u": "User",
      "-f": "Match full command line",
      "-a": "List full command line"
    },
    "examples": [
      {
        "command": "pgrep firefox",
        "explanation": "Find firefox PIDs"
      },
      {
        "command": "pgrep -l python",
        "explanation": "List python processes with names"
      },
      {
        "command": "pgrep -u username",
        "explanation": "Find user's process PIDs"
      },
      {
        "command": "pgrep -a nginx",
        "explanation": "Show full command lines"
      }
    ],
    "tips": [
      "Test patterns before using pkill",
      "Use -a to see full commands",
      "Safer than parsing ps output"
    ]
  },
  
  "nohup": {
    "description": "Run command immune to hangups, output to nohup.out",
    "usage": "nohup COMMAND [ARGS]",
    "category": "process_management",
    "tags": ["background", "detach", "persist", "logout"],
    "common_options": {},
    "examples": [
      {
        "command": "nohup long-running-command &",
        "explanation": "Run in background, immune to logout"
      },
      {
        "command": "nohup ./script.sh > output.log 2>&1 &",
        "explanation": "Redirect output to specific file"
      }
    ],
    "tips": [
      "Output goes to nohup.out by default",
      "Use & to run in background",
      "Process continues after logout"
    ]
  },
  
  "screen": {
    "description": "Full-screen window manager with terminal multiplexing",
    "usage": "screen [OPTIONS] [COMMAND]",
    "category": "shell",
    "tags": ["terminal", "multiplex", "session", "detach"],
    "common_options": {
      "-S": "Session name",
      "-ls": "List sessions",
      "-r": "Reattach to session",
      "-d": "Detach session"
    },
    "examples": [
      {
        "command": "screen",
        "explanation": "Start new screen session"
      },
      {
        "command": "screen -S mysession",
        "explanation": "Start named session"
      },
      {
        "command": "screen -ls",
        "explanation": "List all sessions"
      },
      {
        "command": "screen -r mysession",
        "explanation": "Reattach to session"
      }
    ],
    "tips": [
      "Ctrl+A D to detach",
      "Ctrl+A C to create window",
      "Survives disconnection"
    ]
  },
  
  "tmux": {
    "description": "Terminal multiplexer - better than screen",
    "usage": "tmux [COMMAND]",
    "category": "shell",
    "tags": ["terminal", "multiplex", "session", "window"],
    "common_options": {
      "new": "New session",
      "attach": "Attach to session",
      "ls": "List sessions",
      "kill-session": "Kill session"
    },
    "examples": [
      {
        "command": "tmux",
        "explanation": "Start new session"
      },
      {
        "command": "tmux new -s work",
        "explanation": "Start named session"
      },
      {
        "command": "tmux ls",
        "explanation": "List sessions"
      },
      {
        "command": "tmux attach -t work",
        "explanation": "Attach to session"
      }
    ],
    "tips": [
      "Ctrl+B D to detach",
      "Ctrl+B C to create window",
      "More powerful than screen"
    ]
  },
  
  "cut": {
    "description": "Remove sections from lines of files",
    "usage": "cut [OPTIONS] FILE",
    "category": "text_processing",
    "tags": ["text", "column", "extract", "field"],
    "common_options": {
      "-d": "Delimiter",
      "-f": "Fields to select",
      "-c": "Characters to select",
      "-b": "Bytes to select"
    },
    "examples": [
      {
        "command": "cut -d: -f1,3 /etc/passwd",
        "explanation": "Extract fields 1 and 3 (colon delimiter)"
      },
      {
        "command": "cut -c1-10 file.txt",
        "explanation": "Extract first 10 characters"
      },
      {
        "command": "echo 'a:b:c:d' | cut -d: -f2-3",
        "explanation": "Extract fields 2-3: b:c"
      }
    ],
    "tips": [
      "Great for column extraction",
      "Use with pipes",
      "Simpler than awk for basic tasks"
    ]
  },
  
  "paste": {
    "description": "Merge lines of files",
    "usage": "paste [OPTIONS] FILE1 FILE2",
    "category": "text_processing",
    "tags": ["merge", "combine", "column", "join"],
    "common_options": {
      "-d": "Delimiter (default tab)",
      "-s": "Serial (one file at a time)"
    },
    "examples": [
      {
        "command": "paste file1 file2",
        "explanation": "Merge side by side with tab"
      },
      {
        "command": "paste -d',' file1 file2",
        "explanation": "Merge with comma"
      },
      {
        "command": "paste -s file.txt",
        "explanation": "Merge all lines into one"
      }
    ],
    "tips": [
      "Opposite of cut",
      "Good for combining columns",
      "Use - for stdin"
    ]
  },
  
  "tr": {
    "description": "Translate or delete characters",
    "usage": "tr [OPTIONS] SET1 [SET2]",
    "category": "text_processing",
    "tags": ["translate", "replace", "delete", "character"],
    "common_options": {
      "-d": "Delete characters",
      "-s": "Squeeze repeats",
      "-c": "Complement SET1"
    },
    "examples": [
      {
        "command": "echo 'hello' | tr 'a-z' 'A-Z'",
        "explanation": "Convert to uppercase"
      },
      {
        "command": "echo 'hello  world' | tr -s ' '",
        "explanation": "Squeeze multiple spaces"
      },
      {
        "command": "echo 'hello123' | tr -d '0-9'",
        "explanation": "Delete all digits"
      },
      {
        "command": "cat file | tr '\\n' ','",
        "explanation": "Replace newlines with commas"
      }
    ],
    "tips": [
      "Works on stdin only",
      "Fast character-level operations",
      "Use ranges: a-z, 0-9"
    ]
  },
  
  "join": {
    "description": "Join lines of two files on common field",
    "usage": "join [OPTIONS] FILE1 FILE2",
    "category": "text_processing",
    "tags": ["merge", "combine", "database", "field"],
    "common_options": {
      "-t": "Field separator",
      "-1": "Join on FILE1 field",
      "-2": "Join on FILE2 field",
      "-a": "Include unmatched lines"
    },
    "examples": [
      {
        "command": "join file1.txt file2.txt",
        "explanation": "Join on first field"
      },
      {
        "command": "join -t: -1 1 -2 1 file1 file2",
        "explanation": "Join colon-delimited files"
      }
    ],
    "tips": [
      "Files must be sorted on join field",
      "Like SQL JOIN",
      "Use sort first if needed"
    ]
  },
  
  "comm": {
    "description": "Compare two sorted files line by line",
    "usage": "comm [OPTIONS] FILE1 FILE2",
    "category": "file_operations",
    "tags": ["compare", "difference", "sorted"],
    "common_options": {
      "-1": "Suppress lines unique to FILE1",
      "-2": "Suppress lines unique to FILE2",
      "-3": "Suppress lines in both files"
    },
    "examples": [
      {
        "command": "comm file1.txt file2.txt",
        "explanation": "Show 3 columns: unique to 1, unique to 2, common"
      },
      {
        "command": "comm -12 file1.txt file2.txt",
        "explanation": "Show only common lines"
      },
      {
        "command": "comm -3 file1.txt file2.txt",
        "explanation": "Show only unique lines"
      }
    ],
    "tips": [
      "Files must be sorted",
      "Use sort first if needed",
      "Useful for set operations"
    ]
  },
  
  "uniq": {
    "description": "Report or omit repeated lines",
    "usage": "uniq [OPTIONS] [INPUT [OUTPUT]]",
    "category": "text_processing",
    "tags": ["unique", "duplicate", "count", "sort"],
    "common_options": {
      "-c": "Count occurrences",
      "-d": "Only duplicates",
      "-u": "Only unique",
      "-i": "Case insensitive"
    },
    "examples": [
      {
        "command": "sort file.txt | uniq",
        "explanation": "Remove duplicate lines"
      },
      {
        "command": "sort file.txt | uniq -c",
        "explanation": "Count occurrences"
      },
      {
        "command": "sort file.txt | uniq -d",
        "explanation": "Show only duplicates"
      }
    ],
    "tips": [
      "Input must be sorted!",
      "Use: sort | uniq",
      "sort -u is similar"
    ]
  },
  
  "column": {
    "description": "Format input into multiple columns",
    "usage": "column [OPTIONS] [FILE]",
    "category": "text_processing",
    "tags": ["format", "table", "align", "columns"],
    "common_options": {
      "-t": "Table format",
      "-s": "Separator",
      "-c": "Output width"
    },
    "examples": [
      {
        "command": "cat data.csv | column -t -s,",
        "explanation": "Format CSV as table"
      },
      {
        "command": "mount | column -t",
        "explanation": "Format mount output nicely"
      }
    ],
    "tips": [
      "Great for making readable tables",
      "Use -t for automatic formatting",
      "Aligns columns nicely"
    ]
  },
  
  "fmt": {
    "description": "Simple optimal text formatter",
    "usage": "fmt [OPTIONS] [FILE]",
    "category": "text_processing",
    "tags": ["format", "wrap", "text", "reflow"],
    "common_options": {
      "-w": "Width (default 75)",
      "-u": "Uniform spacing"
    },
    "examples": [
      {
        "command": "fmt -w 60 file.txt",
        "explanation": "Reflow text to 60 columns"
      },
      {
        "command": "echo 'long line' | fmt",
        "explanation": "Format with default width"
      }
    ],
    "tips": [
      "Good for reformatting paragraphs",
      "Preserves blank lines",
      "Use for email formatting"
    ]
  },
  
  "fold": {
    "description": "Wrap each line to specified width",
    "usage": "fold [OPTIONS] [FILE]",
    "category": "text_processing",
    "tags": ["wrap", "width", "text", "line"],
    "common_options": {
      "-w": "Width (default 80)",
      "-s": "Break at spaces",
      "-b": "Count bytes not columns"
    },
    "examples": [
      {
        "command": "fold -w 40 file.txt",
        "explanation": "Wrap lines at 40 characters"
      },
      {
        "command": "fold -s -w 60 file.txt",
        "explanation": "Wrap at spaces, 60 width"
      }
    ],
    "tips": [
      "Unlike fmt, breaks mid-word unless -s",
      "Good for fixed-width output",
      "Use -s to break at spaces"
    ]
  },
  
  "expand": {
    "description": "Convert tabs to spaces",
    "usage": "expand [OPTIONS] [FILE]",
    "category": "text_processing",
    "tags": ["tabs", "spaces", "convert", "whitespace"],
    "common_options": {
      "-t": "Tab stops (default 8)",
      "-i": "Only initial tabs"
    },
    "examples": [
      {
        "command": "expand file.txt",
        "explanation": "Convert tabs to spaces"
      },
      {
        "command": "expand -t 4 file.txt",
        "explanation": "Use 4-space tabs"
      }
    ],
    "tips": [
      "Default is 8 spaces per tab",
      "Use unexpand to reverse",
      "Good for code formatting"
    ]
  },
  
  "unexpand": {
    "description": "Convert spaces to tabs",
    "usage": "unexpand [OPTIONS] [FILE]",
    "category": "text_processing",
    "tags": ["spaces", "tabs", "convert", "whitespace"],
    "common_options": {
      "-t": "Tab stops",
      "-a": "All spaces (not just initial)"
    },
    "examples": [
      {
        "command": "unexpand file.txt",
        "explanation": "Convert initial spaces to tabs"
      },
      {
        "command": "unexpand -a file.txt",
        "explanation": "Convert all spaces to tabs"
      }
    ],
    "tips": [
      "Opposite of expand",
      "Default converts only leading spaces",
      "Use -a for all spaces"
    ]
  },
  
  "strings": {
    "description": "Print printable strings in files",
    "usage": "strings [OPTIONS] FILE",
    "category": "file_operations",
    "tags": ["binary", "text", "extract", "debug"],
    "common_options": {
      "-n": "Minimum length (default 4)",
      "-a": "Scan whole file",
      "-t": "Show offset"
    },
    "examples": [
      {
        "command": "strings binary_file",
        "explanation": "Extract text from binary"
      },
      {
        "command": "strings -n 10 binary",
        "explanation": "Find strings 10+ chars"
      },
      {
        "command": "strings /bin/ls | grep -i version",
        "explanation": "Find version info"
      }
    ],
    "tips": [
      "Great for binary analysis",
      "Find hidden text in files",
      "Use with grep for searching"
    ]
  },
  
  "hexdump": {
    "description": "Display file in hexadecimal",
    "usage": "hexdump [OPTIONS] FILE",
    "category": "file_operations",
    "tags": ["hex", "binary", "dump", "debug"],
    "common_options": {
      "-C": "Canonical hex+ASCII",
      "-n": "Length to read",
      "-s": "Skip offset"
    },
    "examples": [
      {
        "command": "hexdump -C file.bin",
        "explanation": "Hex dump with ASCII"
      },
      {
        "command": "hexdump -n 100 file",
        "explanation": "First 100 bytes only"
      }
    ],
    "tips": [
      "Use -C for readable format",
      "xxd is similar",
      "Good for binary inspection"
    ]
  },
  
  "xxd": {
    "description": "Make hexdump or reverse",
    "usage": "xxd [OPTIONS] [FILE]",
    "category": "file_operations",
    "tags": ["hex", "binary", "dump", "reverse"],
    "common_options": {
      "-r": "Reverse (hex to binary)",
      "-p": "Plain hex",
      "-l": "Length",
      "-s": "Start offset"
    },
    "examples": [
      {
        "command": "xxd file.bin",
        "explanation": "Hexdump"
      },
      {
        "command": "xxd -p file.bin",
        "explanation": "Plain hex output"
      },
      {
        "command": "xxd -r dump.hex output.bin",
        "explanation": "Convert hex to binary"
      }
    ],
    "tips": [
      "Can reverse hex to binary",
      "Cleaner than hexdump",
      "Ships with vim"
    ]
  },
  
  "od": {
    "description": "Dump files in octal and other formats",
    "usage": "od [OPTIONS] [FILE]",
    "category": "file_operations",
    "tags": ["octal", "hex", "dump", "binary"],
    "common_options": {
      "-x": "Hexadecimal",
      "-c": "ASCII characters",
      "-A": "Address radix",
      "-N": "Limit bytes"
    },
    "examples": [
      {
        "command": "od -c file.txt",
        "explanation": "Show characters"
      },
      {
        "command": "od -x file.bin",
        "explanation": "Hexadecimal dump"
      }
    ],
    "tips": [
      "POSIX standard tool",
      "Multiple output formats",
      "Use hexdump/xxd for hex"
    ]
  },
  
  "split": {
    "description": "Split file into pieces",
    "usage": "split [OPTIONS] FILE [PREFIX]",
    "category": "file_operations",
    "tags": ["split", "divide", "chunk", "parts"],
    "common_options": {
      "-b": "Split by bytes",
      "-l": "Split by lines",
      "-n": "Number of chunks",
      "-d": "Numeric suffix"
    },
    "examples": [
      {
        "command": "split -l 1000 large.txt part_",
        "explanation": "Split into 1000-line files"
      },
      {
        "command": "split -b 1M video.mp4 chunk_",
        "explanation": "Split into 1MB chunks"
      },
      {
        "command": "split -n 5 file.txt",
        "explanation": "Split into 5 equal parts"
      }
    ],
    "tips": [
      "Use cat to rejoin: cat part_* > original",
      "Default suffix is aa, ab, ac...",
      "Use -d for numeric suffixes"
    ]
  },
  
  "csplit": {
    "description": "Split file into sections by context",
    "usage": "csplit FILE PATTERN",
    "category": "file_operations",
    "tags": ["split", "pattern", "context", "sections"],
    "common_options": {
      "-f": "Output prefix",
      "-k": "Keep files on error",
      "-n": "Suffix digits"
    },
    "examples": [
      {
        "command": "csplit file.txt '/^Chapter/' '{*}'",
        "explanation": "Split at each 'Chapter' line"
      },
      {
        "command": "csplit log.txt '%ERROR%' '/WARNING/' '{*}'",
        "explanation": "Complex pattern splitting"
      }
    ],
    "tips": [
      "Context-aware splitting",
      "Uses regex patterns",
      "More powerful than split"
    ]
  },
  
  "gzip": {
    "description": "Compress files",
    "usage": "gzip [OPTIONS] [FILE]",
    "category": "file_operations",
    "tags": ["compress", "zip", "archive", "gz"],
    "common_options": {
      "-d": "Decompress (same as gunzip)",
      "-c": "Write to stdout",
      "-k": "Keep original file",
      "-9": "Best compression",
      "-1": "Fast compression"
    },
    "examples": [
      {
        "command": "gzip file.txt",
        "explanation": "Compress to file.txt.gz"
      },
      {
        "command": "gzip -k file.txt",
        "explanation": "Compress, keep original"
      },
      {
        "command": "gzip -d file.txt.gz",
        "explanation": "Decompress"
      }
    ],
    "tips": [
      "Replaces file by default",
      "Use -k to keep original",
      "gunzip is same as gzip -d"
    ]
  },
  
  "gunzip": {
    "description": "Decompress gzip files",
    "usage": "gunzip [OPTIONS] FILE",
    "category": "file_operations",
    "tags": ["decompress", "unzip", "extract", "gz"],
    "common_options": {
      "-c": "Write to stdout",
      "-k": "Keep original",
      "-f": "Force overwrite"
    },
    "examples": [
      {
        "command": "gunzip file.txt.gz",
        "explanation": "Decompress file"
      },
      {
        "command": "gunzip -c file.gz | less",
        "explanation": "View without extracting"
      }
    ],
    "tips": [
      "Same as gzip -d",
      "Removes .gz extension",
      "Use zcat to view"
    ]
  },
  
  "bzip2": {
    "description": "Compress files with bzip2 algorithm",
    "usage": "bzip2 [OPTIONS] [FILE]",
    "category": "file_operations",
    "tags": ["compress", "bz2", "archive"],
    "common_options": {
      "-d": "Decompress",
      "-k": "Keep original",
      "-z": "Force compression",
      "-9": "Best compression (default)"
    },
    "examples": [
      {
        "command": "bzip2 file.txt",
        "explanation": "Compress to file.txt.bz2"
      },
      {
        "command": "bzip2 -d file.txt.bz2",
        "explanation": "Decompress"
      }
    ],
    "tips": [
      "Better compression than gzip",
      "Slower than gzip",
      "Use bunzip2 to decompress"
    ]
  },
  
  "bunzip2": {
    "description": "Decompress bzip2 files",
    "usage": "bunzip2 [OPTIONS] FILE",
    "category": "file_operations",
    "tags": ["decompress", "extract", "bz2"],
    "common_options": {
      "-k": "Keep original",
      "-c": "Write to stdout"
    },
    "examples": [
      {
        "command": "bunzip2 file.txt.bz2",
        "explanation": "Decompress file"
      },
      {
        "command": "bunzip2 -c file.bz2 | less",
        "explanation": "View without extracting"
      }
    ],
    "tips": [
      "Same as bzip2 -d",
      "Use bzcat to view",
      "Removes .bz2 extension"
    ]
  },
  
  "xz": {
    "description": "Compress files with xz algorithm",
    "usage": "xz [OPTIONS] [FILE]",
    "category": "file_operations",
    "tags": ["compress", "xz", "lzma", "archive"],
    "common_options": {
      "-d": "Decompress",
      "-k": "Keep original",
      "-z": "Force compression",
      "-9": "Best compression"
    },
    "examples": [
      {
        "command": "xz file.txt",
        "explanation": "Compress to file.txt.xz"
      },
      {
        "command": "xz -d file.txt.xz",
        "explanation": "Decompress"
      },
      {
        "command": "xz -k -9 large.tar",
        "explanation": "Best compression, keep original"
      }
    ],
    "tips": [
      "Best compression ratio",
      "Slower than gzip",
      "Used in Linux kernel tarballs"
    ]
  },
  
  "unxz": {
    "description": "Decompress xz files",
    "usage": "unxz [OPTIONS] FILE",
    "category": "file_operations",
    "tags": ["decompress", "extract", "xz"],
    "common_options": {
      "-k": "Keep original",
      "-c": "Write to stdout"
    },
    "examples": [
      {
        "command": "unxz file.txt.xz",
        "explanation": "Decompress file"
      },
      {
        "command": "unxz -c file.xz | grep pattern",
        "explanation": "Search without extracting"
      }
    ],
    "tips": [
      "Same as xz -d",
      "Use xzcat to view",
      "Removes .xz extension"
    ]
  },
  
  "zcat": {
    "description": "View compressed gzip files",
    "usage": "zcat [FILE]",
    "category": "file_operations",
    "tags": ["view", "cat", "gz", "compressed"],
    "common_options": {},
    "examples": [
      {
        "command": "zcat file.txt.gz",
        "explanation": "View gzipped file"
      },
      {
        "command": "zcat file.gz | grep pattern",
        "explanation": "Search in compressed file"
      },
      {
        "command": "zcat *.gz | less",
        "explanation": "View multiple compressed files"
      }
    ],
    "tips": [
      "Doesn't extract file",
      "Same as gunzip -c",
      "Can pipe to other commands"
    ]
  },
  
  "bzcat": {
    "description": "View compressed bzip2 files",
    "usage": "bzcat [FILE]",
    "category": "file_operations",
    "tags": ["view", "cat", "bz2", "compressed"],
    "common_options": {},
    "examples": [
      {
        "command": "bzcat file.txt.bz2",
        "explanation": "View bz2 file"
      },
      {
        "command": "bzcat log.bz2 | grep ERROR",
        "explanation": "Search compressed log"
      }
    ],
    "tips": [
      "Same as bunzip2 -c",
      "Doesn't extract",
      "Good for log files"
    ]
  },
  
  "xzcat": {
    "description": "View compressed xz files",
    "usage": "xzcat [FILE]",
    "category": "file_operations",
    "tags": ["view", "cat", "xz", "compressed"],
    "common_options": {},
    "examples": [
      {
        "command": "xzcat file.txt.xz",
        "explanation": "View xz file"
      },
      {
        "command": "xzcat archive.tar.xz | tar t",
        "explanation": "List archive contents"
      }
    ],
    "tips": [
      "Same as unxz -c",
      "Fast viewing",
      "Pipe friendly"
    ]
  }
}