The Linux Commandline

The Linux command line (shell) is your primary interface for interacting with a Linux system. This article covers the most commonly used commands to navigate, manage files, and work with processes.

Navigation

Command	Description
pwd	Print current working directory
ls	List files in the current directory
ls -la	List all files including hidden ones with details
cd <dir>	Change directory
cd ..	Go up one directory level
cd ~	Go to home directory

File Management

Command	Description
touch <file>	Create an empty file
mkdir <dir>	Create a new directory
cp <src> <dest>	Copy a file or directory
mv <src> <dest>	Move or rename a file
rm <file>	Delete a file
rm -rf <dir>	Delete a directory and all its contents

Viewing File Contents

Command	Description
cat <file>	Print entire file content
less <file>	Scroll through a file
head -n 10 <file>	Show first 10 lines
tail -n 10 <file>	Show last 10 lines
tail -f <file>	Follow a file in real-time (useful for logs)

Searching

# Search for a string inside files
grep -r "search term" ./

# Find files by name
find . -name "*.log"

# Find files modified in the last 24 hours
find . -mtime -1

Permissions

Every file in Linux has an owner and a set of permissions for the owner, group, and others.

# View permissions
ls -l

# Change permissions (e.g. make a script executable)
chmod +x script.sh

# Change file owner
chown user:group file.txt

Permission notation: rwxr-xr--

• r = read, w = write, x = execute
• First 3 characters: owner — next 3: group — last 3: others

Useful Shortcuts

Shortcut	Description
Ctrl + C	Cancel running command
Ctrl + L	Clear terminal
Tab	Autocomplete file/command name
↑ / ↓	Navigate command history
!!	Repeat last command
sudo !!	Repeat last command with sudo