Linux command reference

127 Linux commands from ls to systemctl, each with the examples from the lessons and what their options do — try them in a terminal in your browser.

alias — Define or display aliases.
apt — command-line interface
apt-get — APT package handling utility -- command-line interface
apt-mark — show, set and unset various settings for a package
awk — pattern scanning and processing language
bash — GNU Bourne-Again SHell
bg — Move jobs to the background.
break — Exit for, while, or until loops.
cat — concatenate files and print on the standard output
cd — Change the shell working directory.
chage — change user password expiry information
chgrp
chmod — change file mode bits
chown — change file owner and group
clear — clear the terminal screen
command — Execute a simple command or display information about commands.
continue — Resume for, while, or until loops.
cp — copy files and directories
crontab — maintain crontab files for individual users (Vixie Cron)
curl — transfer a URL
cut — remove sections from each line of files
date — print or set the system date and time
dd — convert and copy a file
df — report file system space usage
dig — DNS lookup utility
disown — Remove jobs from current shell.
dpkg — package manager for Debian
du — estimate file space usage
echo — Write arguments to the standard output.
env — run a program in a modified environment
exit — Exit the shell.
export — Set export attribute for shell variables.
fg — Move job to the foreground.
find — search for files in a directory hierarchy
free — Display amount of free and used memory in the system
git — the stupid content tracker
gpasswd — administer /etc/group and /etc/gshadow
grep — print lines that match patterns
groupadd — create a new group
groupdel — delete a group
groups — print the groups a user is in
gunzip — compress or expand files
gzip — compress or expand files
head — output the first part of files
history — Display or manipulate the history list.
hostname — show or set the system's host name
id — print real and effective user and group IDs
ifconfig — configure a network interface
ip — show / manipulate routing, network devices, interfaces and tunnels
jobs — Display status of jobs.
journalctl — Print log entries from the systemd journal
kill — Send a signal to a job.
killall — kill processes by name
last — display login, logout and reboot information
lastlog
less — display the contents of a file in a terminal
ln — make links between files
local — Define local variables.
ls — list directory contents
lsof — list open files
man — an interface to the system reference manuals
mkdir — make directories
mv — move (rename) files
nano — Nano's ANOther text editor, inspired by Pico
ncdu — NCurses Disk Usage
netstat — Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships
nginx — HTTP and reverse proxy server, mail proxy server
nohup — run a command immune to hangups, with output to a non-tty
nslookup — query Internet name servers interactively
passwd — change user password
pgrep — look up, signal, or wait for processes based on name and other attributes
ping — send ICMP ECHO_REQUEST to network hosts
pkill — look up, signal, or wait for processes based on name and other attributes
printenv — print all or part of environment
printf — Formats and prints ARGUMENTS under control of the FORMAT.
ps — report a snapshot of the current processes.
pstree — display a tree of processes
pwd — Print the name of the current working directory.
python3 — an interpreted, interactive, object-oriented programming language
readlink — print resolved symbolic links or canonical file names
rm — remove files or directories
rmdir — remove empty directories
scp — OpenSSH secure file copy
screen — screen manager with VT100/ANSI terminal emulation
sed — stream editor for filtering and transforming text
set — Set or unset values of shell options and positional parameters.
sh — command interpreter (shell)
shift — Shift positional parameters.
sleep — delay for a specified amount of time
sort — sort lines of text files
source — Execute commands from a file in the current shell.
ss — another utility to investigate sockets
ssh — OpenSSH remote login client
ssh-copy-id — use locally available keys to authorise logins on a remote machine
ssh-keygen — OpenSSH authentication key utility
stat — display file or file system status
su — run a command with substitute user and group ID
swapon — enable/disable devices and files for paging and swapping
systemctl — Control the systemd system and service manager
tail — output the last part of files
tar — an archiving utility
tee — read from standard input and write to standard output and files
tmux — terminal multiplexer
top — display Linux processes
touch — change file timestamps
tr — translate or delete characters
truncate — shrink or extend the size of a file to the specified size
type — Display information about command type.
unalias — Remove each NAME from the list of defined aliases.
uname — print system information
uniq — report or omit repeated lines
unzip — list, test and extract compressed files in a ZIP archive
uptime — Tell how long the system has been running.
useradd — create a new user or update default new user information
userdel — delete a user account and related files
usermod — modify a user account
vim — Vi IMproved, a programmer's text editor
vmstat — Report virtual memory statistics
w — Show who is logged on and what they are doing.
wc — print newline, word, and byte counts for each file
wget — The non-interactive network downloader.
whereis — locate the binary, source, and manual page files for a command
which — locate a command
who — show who is logged on
whoami — print effective user name
xargs — build and execute command lines from standard input
zip — package and compress (archive) files