add dedup cmdline arg, readd accidentlally removed cmdline handling code

readme.md

@@ -10,7 +10,7 @@ Currently, the library only supports the New ASCII format.
 
 xz and zstd compression types are currently suppored.
 
-This library is primary designed for use in [ugrd](https://github.com/desultory/ugrd) to create CPIO archives for use in initramfs.
+This library is primary designed for use in [ugrd](https://github.com/desultory/ugrd) to create initramfs CPIO archives 
 
 ## Usage
 
@@ -33,6 +33,7 @@ This library is primary designed for use in [ugrd](https://github.com/desultory/
   --relative RELATIVE   append to archive relative to this path
   --absolute            allow absolute paths
   --reproducible        Set mtime to 0, start inodes at 0
+  --deduplicate         Make hardlinks for files with identical content
   --rm RM, --delete RM  delete from archive
   -n NAME, --name NAME  Name/path override for append
   -s SYMLINK, --symlink SYMLINK
@@ -69,4 +70,5 @@ This library is primary designed for use in [ugrd](https://github.com/desultory/
     - `chardev` : A character device
   * CPIO objects are collected in a `pycpio.cpio.archive` object
     - The archive handles duplication, inode generation, name normalization, and other collection related tasks
+
   * All CPIO object types can be initialized from args, bytes, or a file path

src/pycpio/main.py

@@ -15,6 +15,11 @@ def main():
         {"flags": ["--recursive"], "action": "store", "help": "append to archive recursively"},
         {"flags": ["--relative"], "action": "store", "help": "append to archive relative to this path"},
         {"flags": ["--absolute"], "action": "store_true", "help": "allow absolute paths"},
+        {
+            "flags": ["--deduplicate"],
+            "action": "store_true",
+            "help": "deduplicate files (make hardlinks) when file contents match",
+        },
         {"flags": ["--reproducible"], "action": "store_true", "help": "Set mtime to 0, start inodes at 0"},
         {"flags": ["--rm", "--delete"], "action": "store", "help": "delete from archive"},
         {"flags": ["-n", "--name"], "action": "store", "help": "Name/path override for append"},
@@ -61,6 +66,17 @@ def main():
             raise ValueError("Character device requires minor number")
         c.add_chardev(chardev_path, major, minor)
 
+    if append_file := kwargs.get("append"):
+        cmdargs = {
+            "relative": kwargs.get("relative"),
+            "path": Path(append_file),
+            "name": kwargs.get("name"),
+            "absolute": kwargs.get("absolute"),
+        }
+        c.append_cpio(**cmdargs)
+    if recursive_path := kwargs.get("recursive"):
+        cmdargs = {"relative": kwargs.get("relative"), "path": Path(recursive_path)}
+        c.append_recursive(**cmdargs)
 
     if output_file := kwargs.get("output"):
         compression = kwargs.get("compress")