Important Linux commands

All the tools you need as a server admin

It is difficult to compile a definitive list of the most important commands on Linux, as the importance of different commands can vary depending on the specific needs and tasks of the user.

Let's try it anyway! Here is our all-time favorite list of commonly used and important commands on Linux systems, that you should definitely know:

bash - widely used Unix shell
cat - concatenate and display files
cd - change the current directory
cp - copy files and directories
df - display information about free disk space
du - display the size of a file or directory
echo - display a message or the value of a variable
kill - send a signal to a process
less - view the contents of a file one page at a time
ls - list the contents of a directory
man - display the manual page for a command
mc - start the Midnight Commander
mkdir - create a new directory
mv - move or rename files and directories
ping - send a network test packet
ps - display information about running processes
pwd - print the current working directory
rm - delete files and directories
rsync - synchronize files between two systems
screen - run multiple "tabs" in one terminal session
ssh - connect to a remote host using the Secure Shell (SSH) protocol
sudo - execute a command as root
tail - display the last few lines of a file
top - display the top running processes

Here at CleverUptime, we are using all of those commands on a daily basis. They make our life easier and everybody knows them by heart.

If you read this far, you probably know already all the commands above and you're interested to learn about other commands that can help you as an admin.

Great! Here is the extended list:

ab - a tool for benchmarking web servers
alias - create a shortcut for a command
apt - install, remove, and manage software packages
apt-cache - search for and display information about software packages
apt-get - install, remove, and manage software packages
aria2c - download files using different protocols
at - execute a command at a specified time
atop - show performance metrics
awk - perform text processing and data manipulation tasks
blkid - identify and manage filesystem labels and UUIDs
btrfs - manage the btrfs file system
certbot - manage SSL/TLS certificates from Let's Encrypt
chgrp - change the group ownership of a file or directory
chmod - change the permissions of a file or directory
chown - change the owner of a file or directory
comm - compare two sorted files line by line
crontab - schedule a command to be executed at a specified time
cryptsetup - encrypt block devices
curl - transfer data to or from a server
cut - extract fields or columns from a file
date - display the current date and time
dd - copy data between block devices
dd_rescue - rescue data from block devices
diff - compare two files and display the differences
dig - query the domain name system
dmesg - view the kernel's message buffer
dnf - install, remove, and manage software packages on Fedora-based systems
docker - manage software running in containers
dosfsck - check and repair FAT file systems
dpkg - install, remove, and manage Debian package files
e2fsck - check and repair ext file systems
emacs - edit text files with the Emacs editor
emerge - install, remove, and manage software packages on Gentoo-based systems
export - set the value of an environment variable
fdisk - manage partitions on hard drives and SSDs
fdupes - find and manage duplicate files
ffmpeg - manipulate multimedia files
find - search for files and directories
fold - adjust the width of output
free - display information about free and used memory
fsck - check and repair a file system
gcc - compile C files
gdisk - guided partition table manipulation
getent - get information from administrative databases
git - a version control system
grep - search for a pattern of text within a file
groupdel - delete a group
groupmod - modify a group
gunzip - decompress files
gzip - compress or decompress files
halt - shut down the system
head - display the first few lines of a file
host - query DNS servers
hostname - display the hostname of the system
htop - display performance metrics
ifconfig - display information about network interfaces
init - change the runlevel
iostat - display information about the current I/O performance
iotop - display performance metrics for I/O
ip - display and configure network interfaces
iptables - configure the kernel's firewall
join - join lines of two files on a common field
journalctl - display logging information
last - display users who logged in last
ln - manage hard and soft links
locate - search for files and directories using a database
logrotate - organize log files
lp - send files to the printer
lsb_release - display information about your Linux distribution
lsblk - list block devices
lsmod - list loaded kernel modules
lsof - list open files
lspci - list PCI devices
lvcreate - create logical volumes
lvremove - delete logical volumes
lynx - browse the Web in a terminal window
mailq - manage the mail queue
md5sum - calculate the MD5 checksum
mdadm - manage RAID devices
memtest86 - test the RAM
mkfs.btrfs - format a device with btrfs
mkfs.ext4 - format a device with ext4
mkfs.vfat - format a device with FAT
mkfs.xfs - format a device with XFS
mkswap - create swap space
modprobe - add or remove kernel modules
more - view the contents of a file one page at a time
mount - make file systems accessible in the directory tree
mutt - manage emails
mysqldump - create backups of your MySQL database
nano - edit text files with the Nano editor
nc - send data over the network
netconfig - configure network interfaces
netstat - display network statistics
nft - configure the kernel's firewall
nice - run a command with a modified scheduling priority
nmap - scan for open ports and services
nslookup - query DNS servers
ntpq - query NTP servers
openssl - manage SSL certificates
pacman - install, remove, and manage software packages on Arch Linux-based systems
partprobe - re-read the partition table
passwd - set user passwords
paste - combine lines of files
patch - apply a diff file to an original file
pdftk - manipulate PDF files
pkgtool - the Slackware package manager
printenv - display the value of an environment variable
pv - monitor the progress of a pipe
pvcreate - create a physical volume
pwd - print the current working directory
python - run Python scripts
qemu-img - manage virtual machine images
rclone - the swiss army knife for cloud storage
readlink - display information about hard and soft links
reboot - restart the system
renice - alter the priority of a running process
rmdir - delete an empty directory
rmmod - remove Kernel modules
route - modify the IP routing table
rsnapshot - create file system backups
sar - monitor performance metrics
scp - copy files to or from a remote host using the Secure Copy (SCP) protocol
sed - perform text manipulation and substitution tasks
sendmail - send emails
sftp - transfer files to or from a remote host using the Secure File Transfer Protocol (SFTP)
sh - launch the Bourne shell
shutdown - turn off or reboot the system
sleep - do nothing for a specified time
smartctl - show health and performance data of disk drives
snmpwalk - a tool for network management
sort - sort the lines of a file
ss - show information about network connections
ssh-keygen - generate keys for SSH
ssh-copy-id - add SSH keys to a remote server
su - become the superuser
sysctl - a tool for fine-tuning your system
systemctl - manage services
tac - display files in reversed order
tar - create and extract archive files
tcpdump - capture network packages
tee - chaining together standard input and output
telnet - connect to a remote host using the Telnet protocol
timeout - run a command with a time limit
tmux - run multiple "tabs" in one terminal session
touch - create a new file or update the modification time of an existing file
tr - modify standard output
traceroute - display the network path to a host
umount - remove file systems from the directory tree
uname - display information about the system
uniq - remove duplicate lines from a file
unset - unset the value of an environment variable
unzip - extract files from a ZIP archive
update-alternatives - configure default programs for your system
uptime - display the current uptime of the system
usermod - modify users
vi - edit text files with the vi editor
virt-install - create virtual machines
virt-manager - manage virtual machines
vmstat - display performance statistics
watch - run a program in regular intervals
wc - count the number of lines, words, and characters in a file
wget - download files from the Web
whereis - display the location of a command, file, or manual page
which - display the path of a command
who - display a list of users which are currently logged in
xargs - transform text into commands
xfs_repair - repair XFS file systems
xz - compress or decompress files
yast - configure a SUSE based system
yum - install, remove, and manage software packages on Red Hat-based systems
zip - compress files into a ZIP archive
zstd - compress or decompress files
zypper - install, remove, and manage software packages on openSUSE-based systems

This is just a small selection of the many commands that are available on Linux systems. There are many other important and useful commands that may be specific to certain applications, programming languages, or tasks, and it is always a good idea to familiarize yourself with the commands that are relevant to your work.