Listing Files (ls)

The ls command lists files and directories. It's one of the most frequently used commands in Linux.

Basic Usage

Common Options

Option	Description
-l	Long format (detailed listing)
-a	Show all files (including hidden)
-h	Human-readable sizes (KB, MB, GB)
-R	Recursive (include subdirectories)
-t	Sort by modification time
-S	Sort by size
-r	Reverse sort order

Long Format (-l)

The -l option shows detailed information:

-rw-r--r-- 1 user group 4096 Jan  7 10:00 file.txt

Breaking it down:

• -rw-r--r-- - Permissions
• 1 - Number of links
• user - Owner
• group - Group
• 4096 - Size in bytes
• Jan 7 10:00 - Last modified
• file.txt - Filename

Hidden Files (-a)

Files starting with . are hidden:

Combining Options

Options can be combined:

ls -la     # Long format + all files
ls -lah    # Long + all + human-readable
ls -lt     # Long format, sorted by time
ls -lS     # Long format, sorted by size

Listing Specific Directories

You can list any directory by specifying its path:

ls /etc           # List /etc directory
ls ~/documents    # List documents in home
ls ..             # List parent directory

Exercise: List All Files

Use ls with options to see all files including hidden ones:

Color Output

Most modern systems color-code ls output:

• Blue: Directories
• Green: Executable files
• Cyan: Symbolic links
• Red: Archives
• White: Regular files

Quick Reference

Command	What it shows
ls	Files in current directory
ls -l	Detailed listing
ls -a	All files including hidden
ls -la	Detailed listing of all files
ls -lh	Detailed with readable sizes
ls path/	Files in specified directory

Key Takeaways

• ls lists directory contents
• Use -l for detailed information
• Use -a to see hidden files
• Combine options like -la for both
• Colors help identify file types