Linux Commands

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Linux is a Unix-Like operating system. All the Linux/Unix commands are run in the terminal provided by the Linux system. This terminal is just like the command prompt of Windows OS. Linux/Unix commands are case-sensitive. The terminal can be used to accomplish all Administrative tasks. This includes package installation, file manipulation, and user management. Linux terminal is user-interactive. The terminal outputs the results of commands which are specified by the user itself. Execution of typed command is done only after you press the Enter key. A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Commands	Description
access	Used to check whether the calling program has access to a specified file. It can be used to check whether a file exists or not
accton	Used to turn on or turn off the process for accounting or change info process accounting file
aclocal	Used to automatically generate aclocal.m4 files from configure.in file
acpi	Used to display the battery status and other ACPI information
acpi_available	Tests whether ACPI (Advanced Configuration and Power Interface) subsystem is available or not
acpid	It provides intelligent power management on a system and is used to notify the user-space programs about the ACPI events
addr2line	Used to convert addresses into file names and line numbers
agetty	It is a Linux version of getty, which is a Unix program running on a host computer that manages physical or virtual terminals to allow multi-user access
alias	Instructs the shell to replace one string with another string while executing the commands
amixer	It is a command-line mixer for ALSA(Advanced Linux Sound Architecture) sound-card driver
aplay	It is a command-line audio player for ALSA(Advanced Linux Sound Architecture) sound card drivers.
aplaymidi	Used to play standard MIDI(Musical Instrument Digital Interface) files, by sending the content of a MIDI file to an ALSA(Advanced Linux Sound Architecture) MIDI port
apropos	It helps the user when they don’t remember the exact command but knows a few keywords related to the command that define its uses or functionality
apt	Provides a high-level CLI (Command Line Interface) for the package management system and is intended as an interface for the end user which enables some options better suited for interactive usage by default compared to more specialized APT tools like apt-cache and apt-get
apt-get	It is a command-line tool which helps in handling packages in Linux
aptitude	Opens up a highly built-in interface to interact with the package manager of the machine
ar	Used to create, modify and extract the files from the archives
arch	Used to print the computer architecture
arp	It manipulates the System’s ARP cache. It also allows a complete dump of the ARP cache
aspell	Used as a spell checker in Linux
atd	It is a job scheduler daemon that runs jobs scheduled for later execution
atrm	Used to remove the specified jobs. To remove a job, its job number is passed in the command
atq	It displays the list of pending jobs which are scheduled by the user
autoconf	Used in Linux to generate configuration scripts
autoheader	Used to create a template file of C “#define” or any other template header for configure to use
automake	Used for automatically generating Makefile.in files compliant with the set GNU Coding Standards
autoreconf	Used to create automatically buildable source code for Unix-like systems
autoupdate	Used to update configure.in file in our Linux system to a newer Autoconf.
awk	It is a scripting language used for manipulating data and generating reports

banner	Used to print the ASCII character string in large letter to standard output
basename	It strips directory information and suffixes from file names i.e. it prints the file name NAME with any leading directory components removed
batch	Used to read commands from standard input or a specified file and execute them when system load levels permit i.e. when the load average drops below 1.5
bc	Used for command line calculator
bg	Used to place foreground jobs in background
biff	A mail notification system for unix that notifies the user at the command line when new mail arrives and tells from whom it is
bind	Used to set Readline key bindings and variables
bison	It is basically a parser generator similar to yacc
break	Used to terminate the execution of for loop, while loop and until loop
builtin	Used to run a shell builtin, passing it arguments(args), and also to get the exit status
bzcmp	Used to invoke the cmp utility on bzip2 compressed files
bzdiff	Used to compare the bzip2 compressed files
bzgrep	Used to search for a pattern or an expression but inside a bzip2-compressed file
bzip2	Used to compress and decompress the files
bzless	It does not have to read the entire input file before starting, so with a large file, it starts up faster
bzmore	Used as a filter for CRT viewing of bzip2 compressed files, which are saved with .bz2 suffix

cal	Used to see the calendar of a specific month or a whole year. By default, it shows current month’s calendar as output
case	It is the best alternative when we had to use multiple if/elif on a single variable
cat	Reads data from file and gives their content as output. It helps us to create, view, concatenate files
cc	It is used to compile the C language codes and create executables
ccrypt	It is a command line tool for encryption and decryption of data
cd	Known as change directory command. It is used to change current working directory
cfdisk	It displays or manipulates the disk partition table by providing a text-based “graphical” interface
chage	Used to view and change the user password expiry information
chattr	It is a file system command which is used for changing the attributes of a file in a directory
chfn	It allows you to change a user’s name and other details easily. chfn stands for Change finger
chgrp	Used to change the group ownership of a file or directory
chkconfig	Used to list all available services and view or update their run level settings
chmod	Used to change the access mode of a file
chown	Used to change the file Owner or group
chpasswd	Used to change password for multiple users at a time
chroot	Used to change the root directory
chrt	Used for manipulating the real-time attributes of a process
chsh	Used to change the user’s login shell(currently login shell)
chvt	Used to switch between the different TTY (TeleTYpewriter) terminals available
cksum	Used to display a CRC(Cyclic Redundancy Check) value, the byte size of the file and the name of the file to standard output
clear	Used to clear the terminal screen
cmp	Used to compare the two files byte by byte and helps you to find out whether the two files are identical or not
col	It is used to filter out reverse line feeds. The col utility simply reads from the standard input and writes to standard output
colcrt	Used to format the text processor output so that it can be viewed on Cathode Ray Tube displays
colrm	Removes selected columns from a file
column	Used to display the contents of a file in columns
comm	Compares two sorted files line by line and write to standard output; the lines that are common and the lines that are unique
compress	Used to reduce the file size. After compression, the file will be available with an added .Z extension
continue	Used to skip the current iteration in for, while and until loop
cp	Used to copy files or group of files or directory
cpio	cpio stands for “copy in, copy out“. It is used for processing the archive files like .cpio or .tar. This command can copy files to and from archives
cpp	It is automatically used by C compiler to transform your program before compilation
cron	A software utility, offered by Linux-like operating system which automates the scheduled task at a predetermined time
crontab	A list of commands that you want to run on a regular schedule, and also the name of the command used to manage that list
csplit	Used to split any file into many parts as required by the user
ctags	It allows quick access across the files (For example quickly seeing definition of a function)
cupsd	It is a type of scheduler for CUPS (Common Unit Printing System). It implements the printing system on the basis of the Internet Printing Protocol
curl	A tool to transfer data to or from a server, using any of the supported protocols
cut	For cutting out the sections from each line of files and writing the result to standard output
cvs	Used to store the history of a file. Whenever a file gets corrupted or anything goes wrong “cvs” help us to go back to the previous version and restore our file

date	Used to display the system date and time. It is also used to set date and time of the system
dc	Used to evaluate arithmetic expressions. It evaluates expressions in the form of a postfix expression
dd	It is a command-line utility for Unix and Unix-like operating systems whose primary purpose is to convert and copy files
declare	Used to declare shell variables and functions, set their attributes and display their values
depmod	Used to generate a list of dependency description of kernel modules and its associated map files
df	Used to display information related to file systems about total space and available space
diff	Used to display the differences in the files by comparing the files line by line
diff3	Used to compare the three files line by line
dir	Used to list the contents of a directory
dirname	Used to remove the trailing forward slahes “/” from the NAME and prints the remaining portion
dirs	Used to display the list of currently remembered directories
disable	Used to stop the printers or classes
dmesg	Used to examine the kernel ring buffer and print the message buffer of kernel
dmidecode	Used when the user wants to retrieve system’s hardware related information such as Processor, RAM(DIMMs), BIOS detail, etc. of Linux system in a readable format
domainname	Used to return the Network Information System (NIS) domain name of the host
dos2unix	Converts a DOS text file to UNIX format
dosfsck	Diagnoses MS-DOS file system for problems and attempts to repair them
dstat	Used to retrieve information or statistics form components of the system such as network connections, IO devices, or CPU, etc.
du	Used to track the files and directories which are consuming excessive amount of space on hard disk drive
dump	Used to backup the filesystem to some storage device
dumpe2fs	Used to print the super block and blocks group information for the filesystem present on device
dumpkeys	Used for the dump keyboard translation tables

echo	Used to display line of text/string that are passed as an argument
ed	Used for launching the ed text editor which is a line-based text editor with a minimal interface which makes it less complex for working on text files i.e creating, editing, displaying and manipulating files
egrep	It treats the pattern as an extended regular expression and prints out the lines that match the pattern
eject	It allows ejecting a removable media (typically a CD-ROM, floppy disk, tape, or JAZ or ZIP disk) using the software
emacs	It is a editor having simple user interface. Also, there is no insert mode in this editor. It only have editing mode.
enable	Used to start the printers or classes
env	Used to either print environment variables. It is also used to run a utility or command in a custom environment
eval	Built-in command used to execute arguments as a shell command
ex	It is a text editor in Linux which is also termed as the line editor mode of the vi editor
exec	Used to execute a command from the bash itself
exit	Used to exit the shell where it is currently running
expand	Allows you to convert tabs into spaces in a file and when no file is specified it reads from standard input
expect	This command or scripting language works with scripts that expect user inputs. It automates the task by providing inputs
export	It is bash shell BUILTINS commands, which means it is part of the shell. It marks an environment variables to be exported to child-processes
expr	It evaluates a given expression and displays its corresponding output

factor	Used to print the prime factors of the given numbers, either given from command line or read from standard input
fc	Used to list, edit or re-execute the commands previously entered into an interactive shell
fc-cache	It scans the font directories and build font cache for applications which use fontconfig for their font handling
fc-list	It is used to list the available fonts and font styles. Using the format option, the list of all fonts can be filtered and sorted out
fdisk	Format disk is a dialog-driven command in Linux used for creating and manipulating disk partition table
fg	Used to put a background job in foreground
fgrep	Used to search for the fixed-character strings in a file
file	Used to determine the type of a file. .file type may be of human-readable(e.g. ‘ASCII text’) or MIME type(e.g. ‘text/plain; charset=us-ascii’)
find	Used to find files and directories and perform subsequent operations on them
finger	It is a user information lookup command which gives details of all the users logged in.
fmt	Works as a formatter for simplifying and optimizing text files
fold	It wraps each line in an input file to fit a specified width and prints it to the standard output
for	Used to repeatedly execute a set of command for every element present in the list
free	Displays the total amount of free space available along with the amount of memory used and swap memory in the system, and also the buffers used by the kernel
Fun	Used to draw various type of patterns on the terminal
function	Used to create functions or methods

g++	Used for preprocessing, compilation, assembly and linking of source code to generate an executable file
gawk	Used for pattern scanning and processing language
gcc	GNU Compiler Collections is used to compile mainly C and C++ language. It can also be used to compile Objective C and Objective C++
gdb	GNU Debugger tool helps to debug the programs written in C, C++, Ada, Fortran, etc.
getent	Used to get the entries in a number of important text files called databases
gpasswd	Used to administer the /etc/group and /etc/gshadow
grep	Searches a file for a particular pattern of characters, and displays all lines that contain that pattern
groupadd	Used to create a new user group
groupdel	Used to delete a existing group
groupmod	Used to modify or change the existing group on Linux system
groups	Groups are the collection of users. Groups make it easy to manage users with the same security and access privileges
grpck	It verifies the integrity of the groups information. It checks that all entries in /etc/group and /etc/gshadow have the proper format and contain valid data
grpconv	It is used to convert to shadow groups. The grpconv command creates a gshadow from the group and an optionally existing gshadow
gs	This command invokes Ghostscript, which is an interpreter of Adobe Systems PostScript and Portable Document Format(PDF) languages
gunzip	Used to compress or expand a file or a list of files in Linux
gzexe	Used to compress executable files and also used to automatically uncompress and execute the files
gzip	This command compresses files. Each single file is compressed into a single file.

halt	Used to instruct the hardware to stop all the CPU functions. Basically, it reboots or stops the system.
hash	Used to maintain a hash table of recently executed programs
hdparm	Used to get statistics about the hard disk, alter writing intervals, acoustic management, and DMA settings
Head	Prints the top N number of data of the given input
help	Displays information about shell built-in commands
hexdump	Used to filter and display the specified files, or standard input in a human readable specified format
history	Used to view the previously executed command
host	Used for DNS (Domain Name System) lookup operations
hostid	Used to displays the Host’s ID in hexadecimal format
hostname	Used to obtain the DNS(Domain Name System) name and set the system’s hostname or NIS(Network Information System) domain name.
hostnamectl	Provides a proper API used to control Linux system hostname and change its related settings
htop	It is a command line utility that allows the user to interactively monitor the system’s vital resources or server’s processes in real time
hwclock	Utility for accessing the hardware clock, also called Real Time Clock (RTC)

iconv	Used to convert some text in one encoding into another encoding
id	Used to find out user and group names and numeric ID’s (UID or group ID) of the current user or any other user in the server
if	Used to execute commands based on conditions
ifconfig	Used to configure the kernel-resident network interfaces.
iftop	It is a network analyzing tool used by system administrators to view the bandwidth related stats
ifup	It basically brings the network interface up, allowing it to transmit and receive data
import	Used for capturing a screenshot for any of the active pages we have and it gives the output as an image file
info	Reads documentation in the info format. It will give detailed information for a command when compared with the main page
insmod	Used to insert modules into the kernel
install	Used to copy files and set attributes
iostat	Used for monitoring system input/output statistics for devices and partitions
iotop	Used to display and monitor the disk IO usage details and even gets a table of existing IO utilization by the process
ip	Used for performing several network administration tasks
ipcrm	Used to remove some IPC(Inter-Process Communication) resources. It eliminates the IPC objects and their associated data structure form the system
ipcs	Shows information on the inter-process communication facilities for which the calling process has read access
iptables	Used to set up and maintain tables for the Netfilter firewall for IPv4, included in the Linux kernel
iptables-save	It will save the current iptables rules in a user specified file, that can be used later when the user wants
iwconfig	Used to display the parameters, and the wireless statistics which are extracted from /proc/net/wireless

join	It is a command line utility for joining lines of two files based on a key field present in both the files
journalctl	Used to view systemd, kernel and journal logs

kill

Used to terminate processes manually. kill command sends a signal to a process which terminates the process

last	Used to display the list of all the users logged in and out since the file /var/log/wtmp was created
less	Used to read contents of text file one page(one screen) per time
let	Used to evaluate arithmetic expressions on shell variables
ln	Used to create links between files
locate	Used to find the files by name
look	Shows the lines beginning with a given string
lsblk	Used to display details about block devices and these block devices(Except ram disk) are basically those files that represent devices connected to the pc.
lshw	Used to generate the detailed information of the system’s hardware configuration from various files in the /proc directory
lsmod	Used to display the status of modules in the Linux kernel. It results in a list of loaded modules
lsof	Provides a list of files that are opened
lsusb	Used to display the information about USB buses and the devices connected to them

mailq	This command in Linux prints the mail queue i.e the list of messages that are there in the mail queue
man	Used to display the user manual of any command that we can run on the terminal
md5sum	To verify data integrity using MD5 (Message Digest Algorithm 5)
mkdir	Allows the user to create directories. This command can create multiple directories at once
modinfo	Used to display the information about a Linux Kernel module
more	Used to view the text files in the command prompt, displaying one screen at a time in case the file is large (For example log files)
mount	Used to mount the filesystem found on a device to big tree structure(Linux filesystem) rooted at ‘/‘
mpstat	Used to report processor related statistics.
mv	Used to move one or more files or directories from one place to another in file system like UNIX

nc(netcat)	It is one of the powerful networking tool, security tool or network monitoring tool.
netstat	Displays various network related information such as network connections, routing tables, interface statistics, masquerade connections, multicast memberships, etc.
nmcli	Used for controlling NetworkManager. nmcli command can also be used to display network device status, create, edit, activate/deactivate, and delete network connections
nslookup	It is a network administration tool for querying the Domain Name System (DNS) to obtain domain name or IP address mapping or any other specific DNS record

od	Used to convert the content of input in different formats with octal format as the default format

passwd	Used to change the user account passwords
paste	Used to join files horizontally (parallel merging) by outputting lines consisting of lines from each file specified, separated by tab as delimiter, to the standard output
pidof	Used to find out the process IDs of a specific running program
ping	Used to check the network connectivity between host and server/host
pinky	It is a user information lookup command which gives details of all the users logged in. Unlike finger, in the pinky, you may trim the information of your interest.
pmap	Used to display the memory map of a process. A memory map indicates how memory is spread out
poweroff	Sends an ACPI signal which instructs the system to power down
printf	Used to display the given string, number or any other format specifier on the terminal window
ps	Used to list the currently running processes and their PIDs along with some other information depends on different options
pwd	It prints the path of the working directory, starting from the root

ranlib	Used to generate index to archive
rcp	Used to copy files from one computer to another computer
read	Reads up the total number of bytes from the specified file descriptor into the buffer
readelf	Used to get information of ELF(Executable and Linkable Format) Files
readlink	Used to print resolved symbolic links or canonical file names
reboot	Instructs the system to restart or reboot
rename	Used to rename the named files according to the regular expression perlexpr
reset	Used to initialize the terminal. This is useful once a program dies leaving a terminal in an abnormal state
restore	Used for restoring files from a backup created using dump
return	Used to exit from a shell function.
rev	Used to reverse the lines characterwise
rm	Used to remove objects such as files, directories, symbolic links and so on from the file system like UNIX
rmdir	Used to remove empty directories from the filesystem in Linux
rmmod	Used to remove a module from the kernel
route	Used when you want to work with the IP/kernel routing table
rsync	It is a software utility for Unix-Like systems that efficiently sync files and directories between two hosts or machines

sar	Used to monitor Linux system’s resources like CPU usage, Memory utilization, I/O devices consumption, etc.
scp	Used to copy file(s) between servers in a secure way.
screen	Provides the ability to launch and use multiple shell sessions from a single ssh session
script	Used to make typescript or record all the terminal activities
scriptreplay	Used to replay a typescript/terminal_activity stored in the log file that was recorded by the script command
sdiff	Used to compare two files and then writes the results to standard output in a side-by-side format
sed	Used for finding, filtering, text substitution, replacement and text manipulations like insertion, deletion search etc.
select	Used to create a numbered menu from which a user can select an option
seq	Used to generate numbers from FIRST to LAST in steps of INCREMENT
setsid	Used to run a program in a new session
shift	Shifts/moves the command line arguments to one position left.
showkey	prints to standard output either the scan codes or the key code or the `ascii’ code of each key pressed
shred	Used in order to delete a file completely from hard disk
shutdown	Used to shutdown the system in a safe way
sleep	Used to create a dummy job. A dummy job helps in delaying the execution
source	Used to read and execute the content of a file(generally set of commands), passed as an argument in the current shell script
sort	Used to sort a file, arranging the records in a particular order
split	Used to split large files into smaller files
ssh	Protocol used to securely connect to a remote server/system
strace	It is one of the most powerful process monitoring, diagnostic, instructional tool of Linux.
stty	Used to change and print terminal line settings
sudo	Used as a prefix of some command that only superuser are allowed to run
sum	Used to find checksum and count the blocks in a file
sync	Used to synchronize cached writes to persistent storage
systemctl	Used to examine and control the state of “systemd” system and service manager

tac	Used to concatenate and print files in reverse
Tail	Prints the last N number of data of the given input
tar	Used to create Archive and extract the Archive files
tee	Reads the standard input and writes it to both the standard output and one or more files
time	Used to execute a command and prints a summary of real-time, user CPU time and system CPU time spent by executing a command when it terminates
top	Provides a dynamic real-time view of the running system
touch	Used to create, change and modify timestamps of a file
tr	It is a command line utility for translating or deleting characters
tracepath	Used to traces path to destination discovering MTU along this path
traceroute	Prints the route that a packet takes to reach the host
Tree	A recursive directory listing program that produces a depth-indented listing of files
tty	It displays the information related to terminal. It basically prints the file name of the terminal connected to standard input
type	Used to describe how its argument would be translated if used as commands

uname	Displays the information about the system
unexpand	Converts each spaces into tabs writing the produced output to the standard output
uniq	It is a command line utility that reports or filters out the repeated lines in a file
unix2dos	Converts a Unix text file to DOS format
until	Used to execute a set of commands as long as the final command in the ‘until’ Commands has an exit status which is not zero
Uptime	Used to find out how long the system is active (running)
useradd	Used to add user accounts to your system
usermod	Used to change the properties of a user in Linux through the command line
username	It provides a set of commands to fetch username and its configurations from the Linux host
users	Used to show the user names of users currently logged in to the current host
userdel	Used to delete a user account and related files

vi	It is the default editor that comes with the UNIX operating system is called visual editor.
vmstat	It is a performance monitoring command of the system as it gives the information about processes, memory, paging, block IO, disk and CPU scheduling
vnstat	Used by system administrators in order to monitor network parameters such as bandwidth consumption or maybe some traffic flowing in or out

w	Used to show who is logged on and what they are doing
wall	Displays a message, or the contents of a file, or otherwise its standard input, on the terminals of all currently logged in users
watch	Used to execute a program periodically, showing output in fullscreen
wc	Used to find out number of lines, word count, byte and characters count in the files specified in the file arguments
Wget	Used to download files from the server even when the user has not logged on to the system and it can work in background without hindering the current process
whatis	Used to get a one-line manual page descriptions
which	Used to locate the executable file associated with the given command by searching it in the path environment variable
while	Used to repeatedly execute a set of command as long as the COMMAND returns true
who	Used to get information about currently logged in user on to system
whoami	Displays the username of the current user when this command is invoked
write	Allows a user to communicate with other users, by copying lines from one user’s terminal to others

xargs	Used to build and execute commands from standard input. It converts input received from standard input into arguments of a command
xdg-open	Used to open a file or URL in the user’s preferred application

yes

Used to print a continuous output stream of given STRING. If STRING is not mentioned then it prints ‘y’

zdiff	Used to invoke the diff program on files compressed via gzip
zdump	Used to print the current time in the specified zone or you can say prints the current time in each zonename named on the command line
zgrep	Used to search out expressions from a given a file even if it is compressed
zip	It is a compression and file packaging utility for Unix. Each file is stored in single .zip {.zip-filename} file with the extension .zip

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Last Updated : 03 Jul, 2023

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