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Linux Commands

This section provides reference information for common Linux commands.

Command Categories

Essential Commands

Command Description Example
ls List directory contents ls -la
cd Change directory cd /etc
pwd Print working directory pwd
cp Copy files or directories cp file.txt backup/
mv Move/rename files or directories mv old.txt new.txt
rm Remove files or directories rm -rf directory/
mkdir Create directories mkdir -p new/sub/dir
grep Search text using patterns grep "error" log.txt
find Search for files find / -name "*.conf"
chmod Change file permissions chmod +x script.sh
chown Change file owner chown user:group file.txt
ps Show process status ps aux
kill Terminate processes kill -9 1234
df Show disk space usage df -h
du Show directory space usage du -sh *
top Display running processes top
man Show manual pages man ls

Command Structure

Most Linux commands follow this basic structure:

command [options] arguments
  • Command: The program name (e.g., ls, cp)
  • Options: Modify the command's behavior (e.g., -l, --all)
  • Arguments: What the command acts upon (e.g., filenames, directories)

Getting Help

There are several ways to get help with commands:

# View the manual page
man command_name

# Get brief help
command_name --help

# Get information about a command
info command_name

# Show a brief description
whatis command_name

Command History

# Show command history
history

# Run previous command
!!

# Run command number 42 from history
!42

# Search command history
Ctrl+R

Command Shortcuts

Shortcut Description
Tab Auto-complete commands and filenames
Ctrl+C Interrupt (kill) the current process
Ctrl+Z Suspend the current process
Ctrl+D Exit the current shell
Ctrl+L Clear the screen
Ctrl+A Move cursor to beginning of line
Ctrl+E Move cursor to end of line
Ctrl+U Cut text from cursor to beginning of line
Ctrl+K Cut text from cursor to end of line
Ctrl+W Cut the word before the cursor
Ctrl+Y Paste text that was cut