Top 200 Linux Commands for DevOps

 

Top 200 Linux Commands for DevOps: The Complete Reference Guide

📅 Published: June 2026
⏱️ Estimated Reading Time: 30 minutes
🏷️ Tags: Linux Commands, DevOps, Command Line, System Administration, Shell Scripting

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Introduction: Why These Commands Matter

Linux is the operating system of the cloud. Over 90% of servers run Linux. Every DevOps engineer must be comfortable at the command line. You don't need to memorize every command, but you need to know what's possible and how to find what you need.

This guide organizes 200 essential Linux commands by category. Each command includes a practical example showing exactly how to use it.

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Part 1: File System Navigation (15 commands)

Command	Purpose	Example
pwd	Print working directory	pwd → /home/user
ls	List files and directories	ls -la (detailed list)
cd	Change directory	cd /var/log
tree	Display directory tree	tree -L 2 (2 levels deep)
mkdir	Create directory	mkdir -p dir1/dir2 (create parents)
rmdir	Remove empty directory	rmdir emptydir
touch	Create empty file or update timestamp	touch newfile.txt
rm	Remove files or directories	rm -rf dir (force recursive)
cp	Copy files or directories	cp -r source dest
mv	Move or rename files	mv old.txt new.txt
ln	Create links	ln -s target link (symbolic)
stat	Display file status	stat filename
file	Determine file type	file script.sh
du	Disk usage	du -sh * (human readable)
df	Disk free space	df -h (human readable)

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Part 2: File Viewing and Editing (15 commands)

Command	Purpose	Example
cat	Concatenate and display files	cat file.txt
less	View file page by page	less largefile.log
more	View file one screen at a time	more file.txt
head	Display first lines	head -20 file.txt
tail	Display last lines	tail -f app.log (follow)
tac	Display file in reverse	tac file.txt
nl	Number lines	nl file.txt
wc	Word count	wc -l file.txt (lines only)
grep	Search for patterns	grep -r "error" /var/log/
egrep	Extended grep	egrep "error|fail" log
fgrep	Fixed string grep	fgrep "exact string" file
sed	Stream editor	sed 's/old/new/g' file.txt
awk	Text processing	awk '{print $1}' file.txt
sort	Sort lines	sort -rn file.txt (reverse numeric)
uniq	Remove duplicate lines	sort file.txt | uniq -c

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Part 3: File Permissions and Ownership (10 commands)

Command	Purpose	Example
chmod	Change file permissions	chmod 755 script.sh
chown	Change file owner	chown user:group file.txt
chgrp	Change group ownership	chgrp developers file.txt
umask	Set default permissions	umask 022
lsattr	List file attributes	lsattr file.txt
chattr	Change file attributes	chattr +i file.txt (immutable)
getfacl	Get file ACL	getfacl file.txt
setfacl	Set file ACL	setfacl -m u:user:rw file.txt
sudo	Execute as superuser	sudo systemctl restart nginx
su	Switch user	su - username

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Part 4: Process Management (15 commands)

Command	Purpose	Example
ps	Process status	ps aux (all users, detailed)
top	Dynamic process view	top then M (sort by memory)
htop	Interactive process viewer	htop (install if needed)
pgrep	Find processes by name	pgrep -l nginx
pidof	Find PID of process	pidof nginx
kill	Terminate process	kill -9 PID (force)
pkill	Kill by name	pkill -f "python app.py"
killall	Kill all processes by name	killall nginx
nice	Set process priority	nice -n 19 slowjob
renice	Change process priority	renice -n 10 -p 12345
nohup	Run immune to hangups	nohup longjob &
bg	Send to background	bg %1
fg	Bring to foreground	fg %1
jobs	List background jobs	jobs -l
wait	Wait for process to finish	wait PID

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Part 5: System Information (15 commands)

Command	Purpose	Example
uname	System information	uname -a (all)
hostname	Show/set hostname	hostname
whoami	Current user	whoami
id	User identity	id
uptime	System uptime and load	uptime
w	Who is logged in	w
who	Who is logged in	who -a
last	Last logins	last -10
lastlog	Last login per user	lastlog
dmesg	Kernel messages	dmesg | tail -20
free	Memory usage	free -h
vmstat	Virtual memory stats	vmstat 2 5 (2 sec, 5 times)
iostat	I/O statistics	iostat -x 1
lscpu	CPU information	lscpu
lsblk	Block devices	lsblk

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Part 6: Network Commands (20 commands)

Command	Purpose	Example
ip	Show/manage network interfaces	ip addr show
ifconfig	Configure network interfaces	ifconfig eth0 (legacy)
ping	Test connectivity	ping -c 4 google.com
traceroute	Trace network path	traceroute google.com
tracepath	Trace path with MTU discovery	tracepath google.com
mtr	My traceroute (ping + traceroute)	mtr google.com
netstat	Network statistics	netstat -tulpn
ss	Socket statistics	ss -tulpn (modern netstat)
nmap	Network scanner	nmap -p 80 192.168.1.1
nc	Netcat (network tool)	nc -zv google.com 80
telnet	Test port connectivity	telnet google.com 80
curl	Transfer data	curl -I https://example.com
wget	Download files	wget https://example.com/file.zip
dig	DNS lookup	dig google.com
nslookup	DNS query	nslookup google.com
host	DNS lookup	host google.com
arp	ARP cache	arp -a
route	Routing table	route -n
iptables	Firewall rules	iptables -L -n
ufw	Uncomplicated firewall	ufw status

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Part 7: Package Management (15 commands)

Debian/Ubuntu (APT)

Command	Purpose	Example
apt update	Update package list	sudo apt update
apt upgrade	Upgrade packages	sudo apt upgrade -y
apt install	Install package	sudo apt install nginx
apt remove	Remove package	sudo apt remove nginx
apt purge	Remove with config	sudo apt purge nginx
apt search	Search packages	apt search nginx
apt show	Show package info	apt show nginx
apt list	List installed	apt list --installed
apt autoremove	Remove unused	sudo apt autoremove
dpkg	Package manager	dpkg -l | grep nginx

Red Hat/CentOS (YUM/DNF)

Command	Purpose	Example
yum update	Update packages	sudo yum update
yum install	Install package	sudo yum install nginx
yum remove	Remove package	sudo yum remove nginx
yum search	Search packages	yum search nginx
yum info	Package info	yum info nginx
dnf	Modern yum	sudo dnf install nginx
rpm	RPM package manager	rpm -qa | grep nginx

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Part 8: Compression and Archiving (10 commands)

Command	Purpose	Example
tar	Archive files	tar -czf archive.tar.gz dir/
gzip	Compress files	gzip file.txt
gunzip	Decompress files	gunzip file.txt.gz
zip	Package and compress	zip archive.zip file1 file2
unzip	Extract zip files	unzip archive.zip
bzip2	Compress (better ratio)	bzip2 file.txt
bunzip2	Decompress bzip2	bunzip2 file.txt.bz2
xz	Compress (high ratio)	xz file.txt
unxz	Decompress xz	unxz file.txt.xz
zcat	Display compressed file	zcat file.gz

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Part 9: Text Processing (20 commands)

Command	Purpose	Example
cut	Extract columns	cut -d',' -f1,3 file.csv
paste	Merge lines	paste file1 file2
tr	Translate characters	tr 'a-z' 'A-Z' < file.txt
sort	Sort lines	sort -k2 -n data.txt
uniq	Unique lines	sort file | uniq -d (duplicates)
comm	Compare files	comm file1 file2
diff	Compare files line by line	diff -u file1 file2
cmp	Compare files byte by byte	cmp file1 file2
patch	Apply diff file	patch < file.patch
join	Join lines from two files	join file1 file2
split	Split file into pieces	split -l 1000 large.log
csplit	Split based on pattern	csplit file '/pattern/'
expand	Convert tabs to spaces	expand -t 4 file.txt
unexpand	Convert spaces to tabs	unexpand -t 4 file.txt
pr	Format for printing	pr -l 60 file.txt
fmt	Format text paragraphs	fmt -w 80 file.txt
fold	Wrap lines	fold -w 80 file.txt
rev	Reverse lines	rev file.txt
shuf	Shuffle lines	shuf file.txt
seq	Generate sequences	seq 1 10

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Part 10: Finding and Searching (10 commands)

Command	Purpose	Example
find	Find files	find /home -name "*.txt"
locate	Find by database	locate nginx.conf
updatedb	Update locate DB	sudo updatedb
which	Locate command	which nginx
whereis	Locate binary/source/man	whereis nginx
type	Command type	type ls
whatis	One-line description	whatis ls
apropos	Search man pages	apropos "copy file"
grep	Search file content	grep -r "TODO" --include="*.py"
ack	Better grep for code	ack "function" (install)

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Part 11: Environment and Shell (10 commands)

Command	Purpose	Example
env	Show environment variables	env
export	Set environment variable	export PATH=$PATH:/usr/local/bin
unset	Remove variable	unset TEMP_VAR
echo	Print to stdout	echo $PATH
printenv	Print environment	printenv HOME
alias	Create command alias	alias ll='ls -la'
unalias	Remove alias	unalias ll
source	Execute file in current shell	source ~/.bashrc
.	Same as source	. ~/.bashrc
history	Command history	history | grep ssh

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Part 12: User Management (10 commands)

Command	Purpose	Example
useradd	Create user	sudo useradd -m username
usermod	Modify user	sudo usermod -aG sudo username
userdel	Delete user	sudo userdel -r username
passwd	Change password	passwd (self) or sudo passwd user
groupadd	Create group	sudo groupadd developers
groupmod	Modify group	sudo groupmod -n newname oldname
groupdel	Delete group	sudo groupdel groupname
groups	Show user groups	groups username
id	Show user identity	id username
who	Who is logged in	who -a

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Part 13: SSH and Remote Access (10 commands)

Command	Purpose	Example
ssh	Secure shell	ssh user@hostname
ssh-keygen	Generate SSH keys	ssh-keygen -t rsa -b 4096
ssh-copy-id	Copy public key	ssh-copy-id user@host
scp	Secure copy	scp file.txt user@host:/path/
rsync	Remote sync	rsync -avz /local/ user@host:/remote/
sftp	Secure FTP	sftp user@host
ssh-agent	SSH key manager	eval $(ssh-agent)
ssh-add	Add key to agent	ssh-add ~/.ssh/id_rsa
ssh-keyscan	Get host public key	ssh-keyscan hostname
screen	Terminal multiplexer	screen -S session

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Part 14: System Administration (20 commands)

Command	Purpose	Example
systemctl	Systemd service manager	systemctl status nginx
journalctl	Systemd logs	journalctl -u nginx -f
service	Service management	service nginx restart (legacy)
crontab	Schedule jobs	crontab -e
at	One-time scheduled job	echo "backup.sh" | at 2am
systemd-analyze	Boot performance	systemd-analyze blame
timedatectl	Time and date	timedatectl set-timezone UTC
date	Show/Set date	date "+%Y-%m-%d"
cal	Calendar	cal 2026
sleep	Delay execution	sleep 5 && echo "done"
watch	Execute periodically	watch -n 1 "df -h"
time	Measure execution time	time ./script.sh
xargs	Build command lines	find . -name "*.log" | xargs rm
tee	Redirect to file and stdout	echo "text" | tee file.txt
script	Record terminal session	script session.log
screen	Terminal multiplexer	screen
tmux	Terminal multiplexer	tmux new -s mysession
logger	Log message to syslog	logger "Backup completed"
wall	Send message to all users	wall "System will reboot"
shutdown	Shutdown system	sudo shutdown -h now

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Part 15: Disk and Filesystem (10 commands)

Command	Purpose	Example
fdisk	Partition table manipulator	sudo fdisk -l
lsblk	List block devices	lsblk
blkid	Block device attributes	sudo blkid
mount	Mount filesystem	mount /dev/sdb1 /mnt
umount	Unmount filesystem	umount /mnt
fsck	Filesystem check	sudo fsck /dev/sda1
mkfs	Create filesystem	sudo mkfs.ext4 /dev/sdb1
dd	Convert and copy	dd if=/dev/sda of=backup.img
badblocks	Check for bad blocks	sudo badblocks -v /dev/sda
smartctl	SMART disk health	sudo smartctl -a /dev/sda

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Part 16: Security Commands (10 commands)

Command	Purpose	Example
openssl	Cryptography toolkit	openssl genrsa -out key.pem 2048
gpg	GNU Privacy Guard	gpg -c secret.txt (encrypt)
md5sum	MD5 checksum	md5sum file.txt
sha256sum	SHA256 checksum	sha256sum file.txt
chmod	Change permissions	chmod 600 ~/.ssh/id_rsa
chown	Change ownership	chown user:group file
umask	Default permissions	umask 027
fail2ban-client	Fail2ban manager	fail2ban-client status sshd
auditctl	Audit system calls	auditctl -l
selinux	SELinux commands	getenforce

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Part 17: Networking Advanced (5 commands)

Command	Purpose	Example
tcpdump	Packet capture	sudo tcpdump -i eth0 port 80
tcpflow	TCP session capture	tcpflow -i eth0 port 80
nethogs	Per-process network	sudo nethogs
iftop	Bandwidth usage	sudo iftop
iptraf	Network statistics	sudo iptraf-ng

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Part 18: Performance Monitoring (5 commands)

Command	Purpose	Example
sar	System activity reporter	sar -u 1 3 (CPU every 1 sec)
mpstat	CPU statistics	mpstat -P ALL 1
pidstat	Process statistics	pidstat 1
perf	Linux profiling	perf top
strace	Trace system calls	strace -p PID

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Quick Reference: Most Important Commands

If you remember only 20 commands, make them these:

bash

# Navigation
ls -la          # List everything
cd /path        # Change directory
pwd             # Where am I?

# File operations
cat file        # View file
less file       # Page through file
tail -f log     # Follow log
grep pattern    # Search
cp -r src dst   # Copy
mv old new      # Move/rename
rm -rf dir      # Delete (careful!)

# Processes
ps aux          # See running processes
top             # Real-time processes
kill -9 PID     # Force kill

# Network
ping host       # Test connectivity
curl URL        # Test web endpoint
ss -tulpn       # See listening ports

# System
df -h           # Disk space
free -h         | Memory usage
uptime          # Load average

# Permissions
chmod 755 file  # Change permissions
sudo command    # Run as root

# Package management
apt update      # Update package list (Debian)
apt install pkg # Install package (Debian)
yum install pkg # Install package (RHEL)

# Help
man command     # Read manual
command --help  # Quick help

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How to Remember Commands

Use man – The manual is your friend

bash

man ls

Use history – See what you've run before

bash

history | grep nginx

Use alias – Create shortcuts

bash

alias ll='ls -la'
alias gs='git status'

Use tldr – Simplified man pages (install first)

bash

tldr tar

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Learn More

Practice Linux commands with hands-on exercises in our interactive labs:
https://devops.trainwithsky.com/