adduser/addgroup
Allows us to add users and groups to the system
agetty
A program which manages physical or virtual terminals and is invoked by init. When it detects a connection, it opens a tty port, asks for a user’s login name and calls up the /bin/login command.
alias
Creates aliases to a Linux command. Its temporary for a session, you can make it permanent by adding them to ~/.bashrc file.
anacron
Used to run commands periodically with a frequency defined in days, weeks and months (Similar to CRON where CRON is appropriate for servers and ACRON is for desktop/laptop machines).
Remember: CRON is a daemon where anacron is not a daemon
apropos
Used to search and display a short man page description of a command/program.
apt
A higher-level package manager.
apt-get
A Front-end package manager.
aptitude
A powerful text-based interface to the package management system.
arch
Displays machine architecture or hardware name.
arp
Maps IP network addresses of a network neighbor with the hardware (MAC) addresses in an IPv4 network.
at [An alternative to cron and anacron]
Schedule tasks to run in a future time.
atq
View jobs in at command queue.
atrm
Used to remove/deletes at command jobs.
awk
A powerful programming language created for text processing and generally used as a data extraction and reporting tool.
batch
Used to schedule tasks to run a future time, similar to the at command.
basename
Prints the name of a file stripping of directories in the absolute path.
bc
Powerful and Arbitrary Precision CLI Calculator.
bg
Sends a process to the background.
bzip2
Used to compress or decompress a file.
cal
Prints the Calendar.
chrgrp
Changes the group ownership of a file.
chmod
Changes File access permissions.
chown
Changes the user/group ownership of a file.
cksum
Display the CRC checksum and byte count of an input file.
clear
Clears the Terminal.
cmp
Compares between bytes of two files.
comm
Compares to two sorted files line-by-line.
cp
Used to Copy files and folders.
date
Displays the system date and time.
dd
Used for copying files, converting and formatting according to flags provided.
df
Shows file system disk space usage.
diff
Compare two files line by line.
dir
Lists the contents of the directory.
dmidecode
A tool for retrieving hardware information of any Linux system.
du
Show disk space usage of files present in a directory as well as its sub-directories.
echo
Prints a text of line provided to it.
eject
Ejects removable media such as DVD/CD ROM or floppy disk from the system.
env
Lists all the current environment variables and used to set them as well.
exit
Used to exit a Shell.
expr
Used to calculate an expression.
factor
Shows the Prime factors of the number.
find
Search for files in a directory as well as its sub-directories.
free
Shows the system memory usage.
grep
Searches for a specified pattern in a file or files.
group
Displays all the names of groups a user is a part of.
Gzip
Helps to compress a file, replaces it with one having a .gz extension.
Gunzip
Expands or restores files compressed with gzip command.
head
Shows first lines (10 lines by default) of the specified file or stdin to the screen.
history
Shows previously used commands or to get info about command executed by a user.
hostname
Used to print or set system hostname in Linux.
hostnamectl
Used to print or modify the system hostname and any related settings.
hwclock
A tool for managing the system hardware clock; read or set the hardware clock.
hwinfo
Used to probe for the hardware present in a Linux system.
id
Shows user and group information for the current user or specified username.
ifconfig
Used to configure a systems network interfaces.
ionice
Used to set or view process I/O scheduling class and priority of the specified process.
iostat
Used to show CPU and input/output statistics for devices and partitions.
ip
Used to display or manage routing, devices, policy routing and tunnels.
iptables
For managing incoming and outgoing traffic via a set of configurable table rules.
iw
Used to manage wireless devices and their configuration.
iwlist
Displays detailed wireless information from a wireless interface.
kill
Used to kill a process using its PID by sending a signal to it.
killall
Used to kill a process by its name.
kmod
Used to manage Linux kernel modules.
last
Displays a listing of last logged in users.
ln
Used to create a soft link between files.
locate
Used to find a file by name.
login
Used to create a new session with the system.
ls
Used to list contents of a directory.
lshw
A minimal tool to get detailed information on the hardware configuration of the machine.
Remember: Invoke it with superuser privileges to get a comprehensive information.
lscpu
Displays system’s CPU architecture information.
lsof
Displays information related to files opened by processes.
lsusb
Shows information about USB buses in the system and the devices connected to them.
man
Used to view the on-line reference manual pages for commands/programs.
md5sum
Used to compute and print the MD5 message digest of a file.
Remember: If run without arguments, debsums checks every file on your system against the stock md5sum files
mkdir
Creates one or more folders.
more
Enables you to view through relatively lengthy text files one screenful at a time.
mv
Used to move a file or folder and also used to rename a file or folder.
nano
A Small and Friendly Text Editor
nc (or) netcat
Used for performing any operation relating to TCP, UDP, or UNIX-domain sockets.
netstat
Displays useful information concerning the Linux networking subsystem like
- network connections,
- routing tables,
- interface statistics,
- masquerade connections,
- and multicast memberships.
nice
Used to show or change the nice value of a running program.
nmap
A popular and powerful open source tool for network scanning and security auditing.
nproc
Shows the number of processing units present to the current process.
openssl
A command line tool for using the different cryptography operations of OpenSSL’s crypto library from the shell.
passwd
Used to create/update passwords.
pid
Displays the process ID of a running program/command.
ping
Used to determine connectivity between hosts on a network.
ps
Shows useful information about active processes running on a system.
pstree
Displays running processes as a tree which is rooted at either PID or init if PID is omitted.
pwd
Displays the name of current/working directory.
rdiff
A powerful local/remote incremental backup script written in Python.
reboot
Used to halt, power-off or reboot a system.
rename
Used to rename many files at once.
rm
Used to remove files or directories.
rmdir
Helps to delete/remove empty directories.
scp
Enables you to securely copy files between hosts on a network.
shutdown
Schedules a time for the system to be powered down.
sleep
Used to delay or pause.
sort
Used to sort lines of text in the specified file(s) or from stdin.
split
Used to split a large file into small parts.
ssh
An application for remotely accessing and running commands on a remote machine.
stat
Used to show a file or file system status.
su
Used to switch to another user ID or become root during a login session.
sudo
Allows a permitted system user to run a command as root or another user.
sum
Used to show the checksum and block counts for each each specified file on the command line.
tac
Concatenates and displays files in reverse.
tail
Used to display the last lines (10 lines by default) of each file to standard output.
talk
Used to talk to another system/network user.
tar
A most powerful utility for archiving files.
tee
Used to read from standard input and prints to standard output.
tree
A tiny, cross-platform command-line program used to recursively list or display the content of a directory in a tree-like format.
time
Runs programs and summarizes system resource usage.
top
Displays all processes on a Linux system in regards to memory and CPU usage and provides a dynamic real-time view of a running system.
touch
Changes file timestamps
tr
A useful utility used to translate or delete characters from stdin, and write the result to stdout or send to a file.
uname
Displays system information such as operating system, network node hostname kernel name, version and release etc.
uniq
Displays or omits repeated lines from input.
uptime
Shows how long the system has been running.
users
Shows the user names of users currently logged in to the current host.
vim
Used to edit all kinds of plain text and program files.
w
Displays system uptime, load averages and information about the users currently on the machine, and what they are doing.
wall
Used to send/display a message to all users on the system.
watch
Runs a program repeatedly while displaying its output on fullscreen.
wc
Used to display newline, word, and byte counts for each file specified, and a total for many files.
wget
A simple utility used to download files from the Web in a non-interactive way.
whatis
Searches and shows a short or one-line manual page descriptions of the provided command name
which
Displays the absolute path of the files which would be executed in the current environment.
who
Shows information about users who are currently logged in.
whereis
Helps us locate the binary, source and manual files for commands.
xargs
A useful utility for reading items from the standard input, delimited by blanks or newlines, and executes the entered command.
yes
Used to display a string repeatedly until when terminated or killed.
zcmp and zdiff
A minimal utilities used to compare compressed files.
zip
A simple and easy-to-use utility used to package and compress files.
zz
Offers quick access to files and directories
and there more commands. Comment Below the commands that are left out...😉
Reference : tecmint.com