ls — Linux basic command

Linux / Basic Linux commands / ls.html

A command that displays a list of files and directories in the current directory or a specified path.

Basic Information

What is this command?

ls is an abbreviation for 'list', and it is the most fundamental command that shows what files and subdirectories exist inside a directory. It can be considered the starting point for working in a Linux terminal.

You can add options to display detailed information such as file hidden status, permissions, owner, size, modification time, and more.

What problem does it solve?

• Check what files are present at the current location.
• Quickly understand file permissions, owner, and size.
• View hidden files.
• Explore the directory structure.

Key Features

Basic List Display

Displays files and directories in the current directory showing only their names.

• Use Case: When you need a quick check of what's in your working directory.
• Result Obtained: A list of file and directory names is displayed.
• Limitation: Hidden files (starting with a dot) are not shown.

Detailed Information Display (-l)

Displays detailed information such as permissions, owner, size, and modification time.

• Use Case: When you need to check file permission issues or size.
• Result Obtained: You can view the metadata for each file, one line at a time.
• Limitation: The output can be long, so it's often used with `less`.

Display Hidden Files (-a)

Displays all files, including hidden files starting with a dot (.).

• Use Case: When you need to check configuration files (e.g., .bashrc, .gitignore).
• Result Obtained: You see the complete list, including hidden files.
• Limitation: The list can become cluttered if there are many system hidden files.

Human-Readable Size Units (-h)

Displays file sizes in human-readable units (KB, MB, GB).

• Use Case: When you need to check disk space.
• Result Obtained: Displays sizes in an easy-to-read format, like 8.0M instead of 8388608.
• Limitation: Must be used with the -l option to be effective.

Installation and Execution

Verify Pre-installation

It is included by default in all Linux distributions.

# Check (usually /bin/ls or /usr/bin/ls)
which ls

# Check version
ls --version

When Separate Installation is Required

Only necessary in very minimal environments. It is already present on most systems.

# Debian/Ubuntu (usually already installed)
sudo apt install coreutils

# Alpine Linux
apk add coreutils

Practical Examples

View Basic List

Check the file list of the current directory.

# List current directory
ls

# List a specific directory
ls /etc

# Check multiple paths simultaneously
ls /etc /var/log

Detailed List and Hidden Files

Check permissions, size, and hidden files.

# Detailed info + hidden files + human-readable sizes
ls -lah

# Example output:
# -rw-r--r-- 1 root root  220 Jan  6  2022 .bash_logout
# -rw-r--r-- 1 root root 3.5K Oct 18 14:14 index.html
# drwxr-xr-x 4 root root 4.0K Oct 18 14:14 programs

Sorting and Filtering

Use sorting by size/time and pattern matching.

# Sort by modification time (newest first)
ls -lt

# Sort by name
ls -lX

# Pattern matching (only *.html files)
ls *.html

# Display only directories
ls -d */