HSH - Holbertonschool Simple shell

This project was about programming a simple shell.
Once executed, this program prints a prompt and wait for the user to type commands.
This simple shell handle executable paths such as /bin/ls, as well as commands like "ls" with and without arguments.
It can be used in non-interactive way.

This Simple shell is coded with C language.

🧰 Requirements :

Installation and compilation

This simple shell was developped on Ubuntu.
To run this program, all .c files in this repository must be compiled together. Make sure you have GCC compiler installed on your device.

In order to get the executable file, use the following line of command :

gcc -Wall -Werror -Wextra -pedantic -std=gnu89 *.c -o hsh

For your consideration, here are some explanations about flags used in gcc command :

• -Wall : every warnings are displayed, allows you to identify problems in code
• -Werror: warnings are treated as errors. You won't be able to compile if any warning appears.
• -Wextra: more warnings (not included in Wall) are displayed
• -pedantic : compiler will generate warnings if code don't respect C standards
• -std=gnu89 : compiler will use C89 standard
• *.c : all files ending by ".c" in the current directory will be compiled
• -o hsh: executable name will be "hsh

Here is a brief description of each files needed :

File name	Description
main.c	contains the starting points of the program.
getpath.c	is a function that reads the PATH variable and stores its directories in an array; required to find executable files
checkpath.c	is a function that check if command line typed in stdin can be found in PATH variable.
check_builtin.c	is a function that check if command line typed in stdin is a built-in command.
split_string.c	is a function that use strtok function to deal with arguments of the command, but also used in getpath.
atoi.c	since using the standard atoi was not allowed, we implemented our own version.
main.h	is our header file, needed to the compiler.
man	contains the man page of the program
AUTHORS	contains names and emails of authors

Authorized functions :

Here is the list of functions we were authorized to use :

access	chdir	close	closedir
execve	exit	_exit	fflush
fork	free	getcwd	getline
getpid	isatty	kill	malloc
open	opendir	perror	printf
fprintf	vfprintf	sprintf	putchar
read	readdir	signal	stat
stat	fstat	strtok	wait
waitpid	wait3	wait4	write

And all functions from string.h.

💡 How to use it :

Start the simple shell

Once compilation is done, use the following command to start the shell :

./hsh

Then, a prompt appears and waits for the user to type commands. You can use :

• An executable pathname : for example /bin/ls
• A command line : for example ls

End the program

Once you want to leave the simple shell, you can type :

exit

or press ctrl + D

Examples of uses

Here are some example of use :

prompt$ /bin/ls
README.md atoi.c check_builtin.c clean_all.c free_array.c hsh main.c main.h path.c printenv printpath prompt split_string.c
prompt$

prompt$ ls
README.md atoi.c check_builtin.c clean_all.c free_array.c hsh main.c main.h path.c printenv printpath prompt split_string.c
prompt$

You can also use the program in a non-interactive way, while in your Linux Shell :

<path_directory>$ echo "ls" | ./hsh
README.md atoi.c check_builtin.c clean_all.c free_array.c hsh main.c main.h path.c printenv printpath prompt split_string.c

Only env and exit works for built-in commands

🧮 Returns et error messages :

Returns

The program returns 0 when no problem occurs.

Here is a recap of all created functions returns :

Function name	Operation	Returns	Error status code
_atoi	Convert a string in to and int	The number converted from a string	/
_printenv	Print environment variables (Built in)	Void	EXIT_FAILURE
frexit	Exit the program (Built-in)	Void	If no arguments are given, exit code will 0 or the last error code that occured. If args are given, status code will be the specified number.
clean_all	Free all the allocated memory	Void	/
free_array	Free an array	Void	/
get_paths	Store paths stored in PATH variable	Pointer to an array of strings or NULL if malloc fails or if PATH is an empty string	EXIT_FAILURE if environ is NULL
check_path	Look into PATH directories for an executable file matching the user's command	Pointer to the path of the executable file, or NULL if Malloc fails, PATH is NULL or no match found	/
split_string	Cut a string using a specific separator and stores the results in a NULL terminated array	Pointer to the array containing the sub-strings or NULL if the string given is NULL or Malloc fails	/
get_line	store line typed by user from stdin, and args in an array	1 if succeed, -1 if getline fails, 0 if split_string fails or command is an empty string	/
go_process	create a subprocess and use execve to execute the command's binary file	Void	EXIT_FAILURE if subprocess fails to be created, exit(127) if execve fails
main	run the sell ; instructions to check if user send à pathname or a command, instructions to check is command is a build in and instructions to find binary file in PATH directories are here	0 if program succeed	exit

Exit code from main

If no match is found between PATH and user's command, the program exit with a status code = 127.

Error messages

---

./hsh: 1: <some_command> : not found

Case 1 - The built in command is not implemented yet : you've tried a built in that is not envor exit. Only env and exitare implemented yet.

Case 2 - The command does not exist : you've tried a path or a command that does not exist.

Case 3 - The command exists but the executable file can't be reached. Here are some possible reasons :

• the external program you are trying to call for is not installed
• the binary file you want to execute is corrupted
• permission to execute the binary file is denied
• your PATH variable has been modified and does not contain the path to your executable.

🔎 Flowchart :

This flowchat explains how the shell works.

📗 Man page :

If you need help, you can access the man page using this command :

man man_hsh

💼 Authors :

Mathieu Majérus - https://github.com/MathieuMjr
Tristan Martinez - https://github.com/mAgAtSuRi