Master Essential Linux Commands: From ls to cd in One Guide

1. ls command

The ls command lists directory contents. Use ls for a simple list, ls -l for detailed view, and ls -a to include hidden files.

root@tecmint:~# ls
Android-Games  Music
Pictures       Public
Desktop        Tecmint.com
Documents      TecMint-Sync
Downloads      Templates

root@tecmint:~# ls -l
total 40588
drwxrwxr-x 2 ravisaive ravisaive 4096 May 8 01:06 Android-Games
...

2. lsblk command

lsblk lists block devices in a tree format; lsblk -l shows a flat list.

root@tecmint:~# lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda    8:0    0 232.9G 0   disk 
├─sda1 8:1    0  46.6G 0   part /
...

3. md5sum command

md5sum calculates and verifies an MD5 hash to check file integrity.

root@tecmint:~# md5sum teamviewer_linux.deb
47790ed345a7b7970fc1f2ac50c97002  teamviewer_linux.deb

4. dd command

dd copies and converts files, commonly used to write ISO images to USB devices.

root@tecmint:~# dd if=/home/user/Downloads/debian.iso of=/dev/sdb1 bs=512M; sync

5. uname command

uname displays system information; uname -a shows all details.

root@tecmint:~# uname -a
Linux tecmint 3.8.0-19-generic #30-Ubuntu SMP Wed May 1 16:36:13 UTC 2013 i686 i686 i686 GNU/Linux

6. history command

history prints the command history. Press Ctrl+R to search previous commands.

root@tecmint:~# history 1 sudo add-apt-repository ppa:tualatrix/ppa 2 sudo apt-get update ...

7. sudo command

sudo (super user do) allows authorized users to run commands as root or another user, offering a safer alternative to su.

“To err is human, but to really foul up everything, you need root password.”

8. mkdir command

mkdir creates a new directory; it fails if the directory already exists.

root@tecmint:~# mkdir tecmint

9. touch command

touch updates a file's access and modification timestamps or creates an empty file if it does not exist.

root@tecmint:~# touch tecmintfile

10. chmod command

chmod changes file permission bits. Permissions are expressed as read (4), write (2), and execute (1) for owner, group, and others.

root@tecmint:~# chmod 777 abc.sh

11. chown command

chown changes file ownership to a specified user and group.

root@tecmint:~# chown server:server Binary

12. apt command

apt (Advanced Package Tool) manages packages on Debian‑based systems. apt-get install installs packages, apt-get update refreshes the package list, and apt-cache searches.

root@tecmint:~# apt-get install mplayer
Reading package lists... Done
...

13. tar command

tar creates and extracts archive files. Use -z for gzip, -j for bzip2.

root@tecmint:~# tar -zxvf abc.tar.gz

14. cal command

cal displays a calendar for a given month and year.

root@tecmint:~# cal
May 2013
Su Mo Tu We Th Fr Sa
    1  2  3  4
 5  6  7  8  9 10 11
...

15. date command

date prints or sets the system date and time.

root@tecmint:~# date
Fri May 17 14:13:29 IST 2013

16. cat command

cat concatenates and displays file contents. Use >> to append and > to overwrite.

root@tecmint:~# cat a.txt b.txt c.txt d.txt abcd.txt

17. cp command

cp copies files or directories; it supports wildcards.

root@tecmint:~# cp /home/user/Downloads abc.tar.gz /home/user/Desktop

18. mv command

mv moves or renames files and directories; use with care.

root@tecmint:~# mv /home/user/Downloads abc.tar.gz /home/user/Desktop

19. pwd command

pwd prints the current working directory.

root@tecmint:~# pwd
/home/user/Desktop

20. cd command

cd changes the current directory. cd ~ goes to the home directory, and cd .. moves to the parent directory. root@tecmint:~# cd /home/user/Desktop This collection of commands equips Linux newcomers with the fundamental tools needed for everyday system navigation, file manipulation, package management, and basic scripting.