Basic Commands

These are the most fundamental Linux commands that every user should know. They form the foundation for interacting with the Linux system.

clear

Clears the terminal screen, giving you a clean workspace.

clear

Options:

-x: Don't clear scrollback buffer
-T TERM: Use this terminal type instead of $TERM

man

Displays the manual pages for commands, providing detailed documentation.

man [section] command

Options:

-k keyword: Search for commands related to a specific keyword
-f command: Display a short description of the command
-w command: Print the location of the man page

Examples:

# View the manual for the ls command
man ls

# Search for commands related to "password"
man -k password

echo

Displays text or variable values to the terminal.

echo [options] [string]

Options:

-n: Do not output a trailing newline
-e: Enable interpretation of backslash escapes

Examples:

# Print a simple message
echo "Hello World"

# Print without a newline at the end
echo -n "No newline"

# Print with escape sequences interpreted
echo -e "Line 1\nLine 2"

date

Displays or sets the system date and time.

date [options] [+format]

Options:

+format: Display date in the specified format
-s "string": Set time described by string

Examples:

# Display current date and time
date

# Display date in a custom format
date "+%Y-%m-%d %H:%M:%S"

# Set the system date (requires root privileges)
sudo date -s "2025-04-10 12:00:00"

whoami

Displays the username of the current user.

whoami

exit

Exits the current shell or terminal session.

exit [n]

Where n is an optional exit code (0 means success).

history

Shows the command history for the current user.

history [options]

Options:

-c: Clear the history list
-d offset: Delete the history entry at position offset

Examples:

# Show command history
history

# Show the last 10 commands
history 10

# Clear history
history -c

uname

Prints system information.

uname [options]

Options:

-a: Show all information
-s: Show kernel name
-r: Show kernel release
-v: Show kernel version
-m: Show machine hardware name
-p: Show processor type
-o: Show operating system

Examples:

# Show all system information
uname -a

# Show only the kernel version
uname -r

alias

Creates shortcuts for commands.

alias [name[=value]]

Examples:

# Create an alias for listing files
alias ll='ls -la'

# List all defined aliases
alias

help

Displays help for shell built-in commands.

help [command]

Examples:

# Get help for the cd command
help cd