ls_al.py

#!/usr/bin/env python3
"""This Python script replicates the functionality of ls -al on macOS. Here's what it does:

"v001 + new :ls_al.py & README.md"

    total 64
    drwxr-xr-x   3 username  staff      96 Dec  7 10:30 .
    drwxr-xr-x  15 username  staff     480 Dec  6 14:22 ..
    -rw-r--r--   1 username  staff    1234 Dec  7 09:15 file.txt
Code generated by Claude handles edge cases like permission errors, missing files, and 
symbolic links, making it a robust replacement for the native ls -al command.

Usage:
    bashpython3 ls_al.py                    # List current directory
    python3 ls_al.py /path/to/dir      # List specific directory
    python3 ls_al.py dir1 dir2         # List multiple directories

Key Features:
   * Lists all files including hidden ones (starting with .)
   * Shows file permissions in the familiar format (e.g., drwxr-xr-x)
   * Displays owner and group names
   * Shows file sizes, modification times, and link counts
   * Handles symbolic links by showing the target
   * Includes the total block count at the top
   * Supports multiple directory arguments
"""
import os
import stat
import pwd
import grp
import time
import sys
from pathlib import Path

def format_permissions(mode):
    """Convert file mode to permission string like 'drwxr-xr-x'"""
    perms = []
    
    # File type
    if stat.S_ISDIR(mode):
        perms.append('d')
    elif stat.S_ISLNK(mode):
        perms.append('l')
    else:
        perms.append('-')
    
    # Owner permissions
    perms.append('r' if mode & stat.S_IRUSR else '-')
    perms.append('w' if mode & stat.S_IWUSR else '-')
    perms.append('x' if mode & stat.S_IXUSR else '-')
    
    # Group permissions
    perms.append('r' if mode & stat.S_IRGRP else '-')
    perms.append('w' if mode & stat.S_IWGRP else '-')
    perms.append('x' if mode & stat.S_IXGRP else '-')
    
    # Other permissions
    perms.append('r' if mode & stat.S_IROTH else '-')
    perms.append('w' if mode & stat.S_IWOTH else '-')
    perms.append('x' if mode & stat.S_IXOTH else '-')
    
    return ''.join(perms)

def format_size(size):
    """Format file size for display"""
    return str(size).rjust(8)

def format_time(timestamp):
    """Format modification time like ls -al"""
    file_time = time.localtime(timestamp)
    current_time = time.localtime()
    
    # If file is from this year, show month/day/time
    # Otherwise show month/day/year
    if file_time.tm_year == current_time.tm_year:
        return time.strftime("%b %d %H:%M", file_time)
    else:
        return time.strftime("%b %d  %Y", file_time)

def get_username(uid):
    """Get username from UID"""
    try:
        return pwd.getpwuid(uid).pw_name
    except KeyError:
        return str(uid)

def get_groupname(gid):
    """Get group name from GID"""
    try:
        return grp.getgrgid(gid).gr_name
    except KeyError:
        return str(gid)

def ls_al(directory='.'):
    """List files in ls -al format"""
    try:
        path = Path(directory)
        if not path.exists():
            print(f"ls: {directory}: No such file or directory")
            return
        
        if path.is_file():
            # If it's a single file, just list that file
            entries = [path]
        else:
            # List all entries including hidden ones
            entries = sorted(path.iterdir(), key=lambda x: x.name.lower())
            # Add . and .. entries for directories
            entries = [path / '.', path / '..'] + entries
        
        # Calculate total blocks (approximation)
        total_blocks = 0
        valid_entries = []
        
        for entry in entries:
            try:
                stat_info = entry.stat()
                total_blocks += stat_info.st_blocks
                valid_entries.append((entry, stat_info))
            except (OSError, PermissionError):
                # Skip files we can't stat
                continue
        
        print(f"total {total_blocks // 2}")  # Convert 512-byte blocks to 1024-byte blocks
        
        for entry, stat_info in valid_entries:
            # Format each component
            permissions = format_permissions(stat_info.st_mode)
            links = str(stat_info.st_nlink).rjust(3)
            owner = get_username(stat_info.st_uid).ljust(8)
            group = get_groupname(stat_info.st_gid).ljust(8)
            size = format_size(stat_info.st_size)
            mod_time = format_time(stat_info.st_mtime)
            name = entry.name
            
            # Handle symbolic links
            if stat.S_ISLNK(stat_info.st_mode):
                try:
                    target = os.readlink(entry)
                    name = f"{name} -> {target}"
                except OSError:
                    pass
            
            print(f"{permissions} {links} {owner} {group} {size} {mod_time} {name}")
            
    except PermissionError:
        print(f"ls: {directory}: Permission denied")
    except Exception as e:
        print(f"ls: {directory}: {e}")

if __name__ == "__main__":
    # Handle command line arguments
    if len(sys.argv) > 1:
        for directory in sys.argv[1:]:
            if len(sys.argv) > 2:
                print(f"{directory}:")
            ls_al(directory)
            if len(sys.argv) > 2:
                print()
    else:
        ls_al()