UNIX Basic Command Line Interface Commands

January 19, 2026 9:25 pm Published by

The Ultimate UNIX Command Reference Guide

Whether you are a system administrator or a developer, mastering the Command Line Interface (CLI) is essential. Below is a categorized list of over 60 essential UNIX commands to help you navigate and manage your system efficiently.

1. File & Directory Management

These commands allow you to navigate the file system and manipulate files and folders.

Command Description Example
ls List directory contents ls -la
cd Change directory cd /var/log
pwd Print working directory (where am I?) pwd
mkdir Make a new directory mkdir my_folder
rmdir Remove an empty directory rmdir my_folder
cp Copy files or directories cp file.txt backup.txt
mv Move or rename files/directories mv old.txt new.txt
rm rm file.txt
touch Create empty file or update timestamp touch index.html
ln Create a link (shortcut) to a file ln -s file.txt link.txt
find Search for files in a directory hierarchy find . -name "*.jpg"
locate Find files by name (faster than find) locate config.php

2. Text Processing & Viewing

Commands for reading, searching, and modifying the contents of text files.

Command Description Example
cat Concatenate and display file content cat file.txt
head Output the first part of files head -n 5 file.txt
tail Output the last part of files tail -f access.log
more File perusal filter for CRT viewing more file.txt
less Advanced file perusal (backwards scrolling) less file.txt
grep Search for patterns in text grep "error" log.txt
sed Stream editor for filtering/transforming text sed 's/old/new/g' file.txt
awk Pattern scanning and processing language awk '{print $1}' file.txt
sort Sort lines of text files sort names.txt
uniq Report or omit repeated lines sort file.txt | uniq
wc Word, line, and character count wc -l file.txt
diff Compare files line by line diff file1.txt file2.txt
echo Display a line of text or variable echo "Hello World"

3. System Information & User Management

Monitor your system health and manage user accounts.

Command Description Example
date Display current date (Y,M,D example) date +"%Y-%m-%d"
whoami Display current effective user ID whoami
who Show who is logged on who
w Show who is logged on and what they are doing w
uptime Tell how long the system has been running uptime
uname Print system information uname -a
passwd Change user password passwd
df Report file system disk space usage df -h
du Estimate file space usage du -sh *
free Display amount of free and used memory free -m
id Print real and effective user and group IDs id username
last Show listing of last logged in users last

4. Network & Connectivity

Tools for communicating with other servers and checking network status.

Command Description Example
ping Send ICMP ECHO_REQUEST to network hosts ping google.com
ssh OpenSSH SSH client (remote login) ssh user@host
scp Secure copy (remote file copy) scp file.txt user@host:/path
wget Non-interactive network downloader wget http://site.com/file.zip
curl Transfer data from or to a server curl -I google.com
ip Show/manipulate routing, devices, policy ip addr show
netstat Print network connections and routing tables netstat -tuln
traceroute Print the route packets trace to network host traceroute google.com

5. Permissions & Process Control

Manage security and running programs.

Command Description Example
chmod Change file mode bits (permissions) chmod 755 script.sh
chown Change file owner and group chown user:group file.txt
sudo Execute a command as another user (root) sudo apt update
ps Report a snapshot of current processes ps aux
top Display Linux processes in real-time top
kill Send a signal to a process (terminate) kill -9 1234
jobs List active jobs in current shell jobs
bg Put a job in the background bg %1
fg Bring a job to the foreground fg %1

6. Miscellaneous Utilities

Helpful tools for everyday tasks.

Command Description Example
man Display the online manual for commands man ls
sleep Delay for a specified amount of time sleep 10
tar Archive utility (tape archive) tar -czvf archive.tar.gz folder
gzip Compress or expand files gzip file.txt
zip/unzip Package and compress (zip) files unzip archive.zip
history Show the command history list history
clear Clear the terminal screen clear
alias Create a shortcut for a command alias ll='ls -la'
exit Exit the current shell or terminal exit

Categorised in: , ,

This post was written by amax

Comments are closed here.