Hello everyone, here is a list of all the linux commands I can think of and can be helpful for your usage.
| Input/output |
|---|
| echo It is used to print string values in the terminal. Examples: echo "Hello World" #Print with a newline echo -n "Hello World" #Print without a newline echo -e "Hello\tWorld" #Print with tab space |
| printf It is used to print formatted string values in the terminal. Examples: printf "Hello World" #Print without a newline printf "Hello World\n" #Print with a newline printf "The price of the book is %0.2f\n" 56.856 #Print the formatted data |
| read It is used to take input from the user. Examples: read variable #Take single input read variable1, variable2, variable3 #Take multiple inputs read - p "enter your name: " variable #Take input with prompt read - sp "enter password: " variable #Take secret input read - t 5 - p "Enter your pin : " pin_number #Take input with time limit read - n 11 mobile #Take input of maximum length |
| pipe It is used to take the output of one process and pass it as the input for another process. The symbol, ‘|’ is for the pipe. Example: # The output of`echo` command will be sent as the input of the`wc` command echo "Hello World" | wc –w |
| Redirection The redirection is used in Linux to change the standard input/output of the device after executing the command. The ‘<’ symbol is used for input redirection and the ‘>’ symbol is used for output redirection. Examples: ls - l > folderList.txt #Redirect output ehco "test" 2 > error.txt #Redirect error into the file ehco "test" 2 >& 1 error.txt #Redirect error into the file and the terminal cat > myfile.txt < folderList.txt #Redirect input data from one file to another file |
| System Information |
| date It is used to print the current date and time of the system in different formats. Examples: date #Print current date and time without formatting date +%m-%d-%Y #Print the current date date +%H:%M:%S #Print the current time date +"%A, %B %d,%Y" #Print the current date with weekday and month name |
| hostname It is used to check or modify the hostname, domain, and IP address. Examples: hostname #Display the hostname hostname -d #Display the domain name hostname -I #Display the IP address hostname -b new_hostname #Set the new hostname |
| uname It is used to print different information about the hardware and the operating system. Examples: uname #Print the kernel name uname –n #Print the hostname uname –m #Print the hardware name uname -o #Print the operating system name uname –a #Print all information related to hardware and OS |
| vmstate It is used to get information about the memory, disk, processes, block IO, paging, and CPU scheduling. Examples: vmstat –a #Display the active and inactive memory of the system vmstat –f #Display the number of forks since boot vmstat -s #Display event counter and memory statistics vmstat -d #Display disk statistics |
| iostate It is used to monitor the statistics of the system input/output of devices and partitions. The sysstat package requires to install before using this command. Examples: Iostat #Print all statistics and report Iostat -c #Print the statistic information of CPU Iostat -d #Print the device report Iostat -x #Print the statistics information in details Iostat -k # Print the statistic in KB or MB Iostat -p #Print the statistics information of block devices Iostat -N #Print the statistics information of lvm2 |
| free It is used to print the detailed report of the system’s memory usage. Examples: free #Print the output in the default format free -h #Print the output in human-readable format free -b #Print the output in bytes free -k #Print the output in KB free -g #Print the output in GB |
| whoami It is used to print the name of the currently logged-in user. Example: whoami #Print the logged-in user's name |
| uptime It is used to print the information about the total running time of the system. Examples: uptime #Print the uptime in the default format uptime -p #Print the uptime in pretty format uptime –s #Print the time since the system is up |
| shutdown It is used to power off or shutdown or restart the system from the terminal. Examples: shutdown #Shutdown normally shutdown –h 0 #Shutdown immediately shutdown –r #Shutdown and restart shutdown –r now #Shutdown and restart immediately shutdown –c #Shutdown can be canceled |
| reboot It is used to reboot the system from the terminal with root privilege. Example: sudo reboot #Reboot the system |
| User Management |
| adduser It is used to add a new user account in the Linux system. The root privilege requires to execute this command. Examples: #Create a new user information in default location sudo adduser username #Create a new user information in the specified location sudo adduser username --home /home/temp/ |
| deluser It is used to remove the Linux user account. The root privilege requires to execute this command. Examples: sudo deluser username #Delete user sudo deluser --remove-home username #Delete user with home directory sudo deluser –force #Delete user forcefully sudo deluser --backup-to /backupUser username #Delete user keeping backup files |
| usermod It is used to modify the information of any existing Linux user. It requires root privilege to execute. Examples: sudo usermod --login newUsername oldUsername #Change the username sudo usermod --uid newID username #Change the ID of an existing user sudo usermod --gid groupname username #Change the group name of an existing user |
| groupadd It is used to create a new group. It requires root privilege to execute this command. Examples: #Create a new group sudo groupadd groupname #Create a group forcefully if it already exists sudo groupadd –f groupname #Create a new group with a particular group id sudo groupadd -g 6723 groupname #Create a new group by defining the range of group id sudo groupadd -K GID_MIN=4000 -K GID_MAX=5000 groupname |
| groupdel It is used to delete an existing group. It requires root privilege to execute this command. Examples: sudo groupdel groupname #Delete the group name sudo groupdel –f groupname #Delete the group forcefully |
| groupmod It is used to modify any existing group. It requires root privilege to execute this command.Examples: sudo groupmod -n newGroupname Groupname #Change the group name sudo groupmod -g 676 Groupname #Change the group id |
| last It is used to print the information about the last login session of the Linux users. Examples: last #Print all last login session information last username #Print the last login session information of a user last -10 #Print the last 10 login session last –p 2022-01-01 #Print the last login session information of a specific date |
| id IT is used to search the username, group name, and the ID of the current user or another user of the server. Examples: id #Print the ID and group information related to the current login user’s id username #Print the ID and group information related to the particular user id -u username #Print the user ID of the particular user id -g username #Print the group ID of the particular user |
| groups It is used to print the primary and supplementary group names for each username or the current process if no username is given. Examples: Groups #Print the group information of the current login user groups username #Print the group information of the specific user groups username1 username2 #Print the group information of the multiple users |
| passwd It is used to change the user’s password. The root user can change the password of all users and other users can change their password only. Examples: passwd #Change the password of the current login user sudo passwd username #Change the password of any user with root privilege |
| sudo It is used to perform the restricted tasks with the root privileges without logging as root user or by logging as the root user. Examples: sudo apt-get update #Update the current system sudo -i #Login as the root user sudo bash #Run bash as the root user sudu !! #Execute the last command with the root privilege |
| su It is used to switch from the current user to another user. Example: su username #Switch to another user without changing the home directory su -l username #Switch to another user by changing the current directory su -p username #Switch to another user by preserving the environment variables |
| Packages |
| apt It is used to install, update, delete and manage different packages in Linux operating system. It requires root privileges. Examples: sudo apt update #Update the installed packages sudo apt upgrade #Upgrade the installed packages sudo apt upgrade packagename #Upgrade specific package |
| apt-get It works like the `apt` command but some commands are used differently by `apt-get` command when it is used in replacement of the `apt` command. Examples: sudo apt-get update #Update the packages sudo apt-get dist-upgrade #Upgrade the packages with full dependencies |
| dpkg It is used to install, remove, manage and query Debian packages and their dependencies. It requires root privilege to use. Examples: #Install the Debian package sudo dpkg –i debian_package_name #Print installed packages related to nano editor sudo dpkg -l '*nano*' #Remove vim editor sudo dpkg -r vim |
| Disk Usage |
| du It is used to get disk usage information. Examples: du #Print the disk usage information in the default format du -h #Print the disk usage information in human-readable format du -c #Print the disk usage information with total measurement value. du -s #Print the summary of the disk usage information du -a #Print disk usage information with the sizes of files and folders |
| df It is used to print the used available disk space information of the file system. Examples: df #Print the used and available disk space in the default format df -h #Print the used and available disk space in human-readable format df -T #Print the used and available disk space with file system type df --total #Print the used and available disk space with total values df -a #Print the used and available disk space with other information |
| fdisk It is used to create or modify the partition tables of the hard disk. Examples: fdisk -l #Print partition table of all devices fdisk /dev/sdb #Run fdisk for the specific device fdisk -l /dev/sda #Print the partition table list of a device |
| mount It is used to attach the file system and removable devices at a particular mount point. Examples: sudo mount #Print all currently attached file system sudo mount -t ext3 #Print the list of all ext3 file system sudo mount /dev/sda1 /mnt/media #Mount a file system and a directory |
| unmount It is used to detach the mounted file system and the device. Examples: sudo umount ext3 #Unmount ext3 file system sudo umount /dev/sdb1 #Unmount sdb1 device |
| Process Management |
| ps It is used to get information related to the processes of the system. Examples: ps #Print the process list of the current shell ps -e #Print the list of all running process ps -a #Print the list of the process that is not associated with the terminal ps -T #Print the list of the process that is associated with the terminal |
| pgrep It is used to search the process ID of the running program based on the specific condition. Examples: pgrep bash #Print the process ID pgrep ssh -l #Print the process name with ID pgrep -u root #Print the process list of a particular user |
| kill It is used to send a signal to a process defined by a PID. The default signal is SIGTERM which terminates the process. Examples: kill –l #Print the available kill signals kill 5645 #Terminate the process based on ID kill -1 9078 #Reload the process based on the ID kill –n 15 7845 8756 #Terminate multiple processes |
| killall It is used to kill any running process forcefully based on the given process name. Examples: killall processname #Kill the process based on name killall -i processname #Ask permission before killing the process killall –u username #Kill process based on the username |
| pkill It is used to send a signal to a process of the running program based on the full or partial process name, username, or other attributes. Examples: pkill firfox #Terminate a particular process pkill -i gedit #Terminate a process in a case-insensitive manner |
| fg It is used to move the background job of the current shell into the foreground. Example: fg %1 #Refer to the specific job number fg %+ #Refer to the current job fg %- #Refer to the previous job |
| bg It is used to restart a stopped background process. Example: bg %1 #Refer to the specific job number bg %+ #Refer to the current job bg %- #Refer to the previous job |
| Scripting Tools |
| sed It is used to search, find-replace, and insert or delete purposes. Examples: #Replace the word, 'World' with the word 'Everyone' echo 'Hello World' | sed 's/World/Everyone/' #Replace the word, 'book' with the word 'e-book' sed 's/book/e-book/g' filename.txt #Delete the 5th line of the file sed '5d' filename.txt |
| awk It is a scripting language that is used for manipulating data and generating a report by pattern scanning and processing. Example: awk '{print}' filename.txt #Print the content of the file awk '/Linux/ {print}' filename.txt #Print those lines of the file that contains ‘Linux’ awk '{print $1,$4}' filename.txt #Print the first and fourth columns of the file |
| sort It is used to sort the content of a file. Examples: sort filename.txt #Sort the string data in ascending order sort –r filename.txt #Sort the string data in descending order sort -n file1.txt #Sort the numeric data in ascending order sort -o output.txt filename.txt #Redirect the sorted output of filename.txt to output.txt |
| wc It is used to count the number of characters, words, and lines of a file or the standard input. Examples: echo "Hello" | wc –c #Count the total characters of the string wc –w filename.txt #Count the total words of a file wc –l filename.txt #Count the total lines of a file |
| uniq It is used to filter the duplicate lines of a file. Examples: uniq filename.txt #Print the file after filtering the duplicate lines uniq –c filename.txt #Print the file after filtering the duplicate lines with number uniq –d filename.txt #Print the duplicate lines of the file only. uniq –u filename.txt #Print the unique lines of the file only |
| tr It is used to convert the string or delete characters from the string. Examples: echo Linux | tr [:lower:] [:upper:] #Change all small letters to capital letters of the string tr A-Z a-z < filename.txt #Change all capital letters to small letters of a file echo "fool" | tr -c 'ool\n' 'b' #Change those characters by ‘b’ that don’t match with ‘ool\n’ |
| File commands |
| touch It is used to create an empty file and change the access or modification timestamp value of the existing file. Examples: touch filename #Create a blank file touch file1, file2, file3 #Create multiple blank files touch -a filename.txt #Modify the access time of an existing file touch -m filename.txt #Modify the modification time of an existing file |
| cat It is used to create, read, and concatenate files. Examples: cat > filename #Create a new file cat filename #Print an existing file cat filename1, filename2, filename3 #Print multiple files cat -n filename #Print an existing file with the line number |
| cp It is used to copy file or group of files or directories. Examples: cp file1.txt file2.txt #Copy the file1.txt to file2.txt cp file1.txt file2.txt dirname #Copy multiple files into a directory cp -i file1.txt file2.txt #Ask before overwriting the existing file cp -f file1.txt file2.txt #Copy file forcefully |
| mv It is used to move files and directories from one location to another location. Examples: mv filename1 filename2 #Move the file mv dircetory1 directory2 #Move the directory mv -i filename directory #Ask for overwriting before moving |
| rm It is used to remove files and directories. Examples: rm filename #Remove a single file rm file1, file2, file3 #Remove multiple files rm -i filename #Ask before deleting rm -r directory #Remove all files and folders of the directory recursively rm -d directory #Remove empty directory |
| ln It is used to create the symbolic link. Examples: ln -s filename #Create a link to a file ln -s filename linkname #Create a link with the linkname ln -sf filename linkname #Create a link forcefully if exists |
| less It is used to read the large file or command output that displays the content of a file or a command output part by part to make the reading task faster. Examples: Less filename #Print the content of a file ps aux | less #Print the command output ps aux | less –N #Print the command output with line number ps aux | less -p "root" #Highlight the word, root in the output |
| more It works similar to `less` command and it has many other features to scroll the content of the large file or command output. Examples: more file.txt #Display the content of a file more -d file..txt #Help user to navigate the content more -p file..txt #Display the page after clearing the previous content more -c file..txt #Display all pages in the same area dmesg | more #Display the content of command output |
| cut It is used to cut the portion of each line from a file and print the output in the terminal. Examples: cut -b 3 file.txt #Print the 3rd character from each line of the file cut -c 2,5 file.txt #Print the 2nd and 5th characters from each line of the file cut -c -3 file.txt #Print the first 3 characters from each line of the file |
| head It is used to read the file from the beginning. Examples: head -n 5 file.txt #Print the first 5 lines of the file head -n -5 file.txt #Print the lines after omitting the last 5 lines head -c 50 file.txt #Print the first 50 characters of the file head -q file1.txt file2.txt #Print the content of multiple files |
| tail It is used to read the file from the end. Examples: tail -n 4 file.txt #Print the last 4 lines of the file tail -n -7 file.txt #Print the lines after omitting the first 7 lines tail -c 50 file.txt #Print the last 50 characters of the file tail -n 5 file1.txt file2.txt #Print the last 5 lines of two files |
| File Permissions |
| chmod It is used to set the permission bits for the files and folders. Examples: #Owner can read & write, the group users can read and others can execute chmod 642 filename #Owner can read, write and execute, the group users can execute and others can read only chmod u=rwx,g=x,o=r filename #Owner can read and write, the group users can write and others can do nothing to the files and folders #of the directory chmod -R 620 dirname |
| chown It is used to change the ownership of a file for the owner or the group users. It requires root privileges to execute. Examples: sudo chown -c username filename #Change the ownership of a file sudo chown :groupname filename #Change the ownership of a group #Change the ownership by mentioning the usernames sudo chown --from=fahmida root linuxhint |
| File Compression and Decompression |
| gzip It is used to compress the file by keeping the original file mode, timestamp and ownership. Examples: gzip filename #Compress single file gzip file1 file2 file3 #Compress multiple files gzip -v filename #Display the percentage of compression gzip -r directory #Compress all files of a directory |
| tar It is used to create compressed achieve files of large files and folders that can be transferred from one location to another.Examples: tar -cvf filename.tar /home/fahmida/ #Create a compress file of .tar extension tar -cvzf filename.tgz /home/fahmida/ #Create a compress file of .tgz extension tar -cvfj filename.bz2 /home/fahmida/ #Create a compress file of .bz2 extension |
| zip It is used to compress the file in .zip format that is supported by many operating systems. Examples: zip file.zip file.txt #Compress the file with .zip extension zip -d file.zip file.txt #Remove the file from the zip archive zip -u file.zip file.txt #Update the file in the zip archive |
| unzip It is used to unzip the files and folders from the zip achieve. Examples: unzip file.zip #Decompress file in the current location from the zip archive sudo unzip file.zip -d /temp #Decompress file in the particular folder from the zip archive |
| Directory operations |
| pwd It is used to know the path of the current working directory. Examples: pwd #Display the current working directory pwd –L #Display the logical working directory pwd –P #Display the physical working directory |
| mkdir It is used to create a new directory. Examples: mkdir dirname #Create a single directory mkdir dir1, dir2, dir3 #Create multiple directory mkdir –m777 dirname #Create a directory with permission |
| rmdir It is used to remove any directory. Examples: rmdir dirname #Remove single directory rmdir dir1, dir2, dir3 #Remove multiple directory #Remove the child directory first and remove the parent directory rmdir -p parent_dir/child_dir |
| ls It is used to print the list of files and folders of the current path or a particular path. Examples: ls #Display the files and folders in the default format ls -a #Display files and folders with hidden files ls -l #Display the files and folders with the detailed information ls -h #Display the files and folders in human-readable format ls -r #Display the files and folders in reverse order ls -F #Display folders with ‘/’ |
| cd It is used to change the directory. Examples: cd dirname #Change to a directory cd dir1/dir2 #Change to a directory that is inside another directory cd / #Change to the root directory cd #Change to the home directory |
| Searching Commands |
| grep It is used to search the particular string in a file. Examples: grep 'test' file.txt #Print the lines that match the word, 'test' grep -i ‘test’ file.txt #Print the lines that match the word, 'test' case-insensitively grep ‘^test’ file.txt #Print the lines that match the word, 'test' at the beginning of the line grep ‘test$’ file.txt #Print the lines that match the word, 'test' at the end of the line |
| locate It is used to search a file by name. Examples: locate filename #Search a particular file locate "*.txt" -n 15 #Search text files with the limit locate -c [.sh]* #Count the number of matches locate -i filename #Search a file in a case-insensitive manner |
| find It is used to search and locate the files and folders based on the condition. Examples: find . -name filename.txt #Search a file in the current directory find . -iname filename.txt #Search a file case-insensitively find /temp -name filename.txt #Search the file in the particular folder find / -type d -name dirname #Search the directory in ‘/’ folder |
| whereis It is used to search the location of the source, binary, and the manual page files for a command. Examples: whereis -l #Find the directories where the `whereis` command will search whereis bash #Find the location of the `bash` whereis man uptime #Find the location of `man` and `uptime` |
| Network Information |
| ping It is used to test a host is reachable or not in the network. Examples: ping www.google.com #Test using the URL address ping 142.250.199.36 #Test using IP address ping -c 5 www.google.com #Test will stop after sending 5 packets ping -i 3 www.google.com #Test using 3 seconds interval |
| ifconfig It is used to configure, manage, and query network interface parameters by using a command-line interface or system configuration script. You have to install the net-tools package to use this command. Examples: ifconfig #Display all active interfaces ifconfig -a #Display all active or inactive interfaces ifconfig eth0 #Display information about the specific interface ifconfig eth0 up #Activate the particular interface ifconfig eth0 down #Deactivate the particular interface ifconfig eth0 172.16.25.125 #Set the IP address for the particular interface |
| dig It is used to search the DNS name servers for DNS lookup. Examples: dig example.com #Find the IP address of the hostname dig 93.184.216.34 #Find the hostname of the IP address dig example.com MX #Find the MX of a hostname |
| netstat It is used to get information about the network activities and display which ports are open or have established connections. It is a useful tool to debug network problems. Examples: netstat –a #Print all ports and connections netstat –at #Print all TCP ports netstat –au #Print all UDP ports netstat -l #Print all listening ports of all protocols |
| ip It is used to bring the interface up or down, assign and remove the address, etc. Examples: ip addr show #Display information of all IP addresses ip addr show dev eth0 #Display information about a single interface sudo ip address add 192.168.10.50/24 dev eth0 #Assign IP to an interface |
| Bash Shortcut Keys |
| alt+ctrl+t It is used to open a new terminal window. |
| ctrl+c It is used to stop the running command. |
| ctrl+a It is used to go to the start of the line. |
| ctrl+e It is used to go to the end of the line. |
| ctrl+u It is used to cut the line before the cursor to the clipboard. |
| ctrl+k It is used to cut the line after the cursor to the clipboard. |
| ctrl+r It is used to search history. |
| ctrl+z It is used to suspend the current foreground process. |
| !! It is used to repeat the last command. |
| !$ It is used to read the last argument of the previous command. |
| !* It is used to read all arguments of the previous command. |
| Bash Script Basics |
| Variables The variable is used to store and read data. Example: website="linuxhint.com" #Assign a string value to a variable echo $website #Print the value of the variable echo "The website name is $website" #Print the variable with another string |
| Length The length of a string can be calculated in bash in different ways. The simple way to count the length is shown below. Example: var="Hello World" #Assign String value echo ${#var} #Print the length of the sting |
| Substring Sometimes it requires cutting the portion of a string that is called substring. Example: var="Hello World" #Assign String value echo "${var:0:5}" #Print the substring, ‘Hello’ echo "${var:6:5}" #Print the substring, ‘World’ |
| Uppercase The string can be converted into uppercase by using `tr` command and ‘^^’ operator. Example: var="Hello" echo $var | tr [:lower:] [:upper:] #Convert to uppercase using `tr` echo ${var^^} #Convert to uppercase using '^^' |
| Lowercase The string can be converted into lowercase by using `tr` command and ‘,,’ operator. Example: var="Hello" echo $var | tr [A-Z] [a-z] #Convert to lowercase using `tr` echo ${var,,} #Convert to lowercase using '^^' |
| If Statement If statement is used to define the conditional statements. Example: str="file.txt" if [[ -f $str ]]; then #Check the file exists or not echo "$str is a file." elif [[ -d $str ]]; then #Check the directory exist or not echo "$str is a directory." else echo "$str is not a fir or directory." fi |
| Case statement The case statement can be used as an alternative to if statement. Example: id=45 case $id in 67) echo "Group-1";; #Match with an ID 45 | 89) echo "Group-2";; #Match with any of two IDs 92 | 12 | 54) echo "Group-3" ;; #Match with any of three IDs *) echo "You are not selected." ;; esac |
| For loop It is used to iterate some statements multiple times or read the array values. Example: for i in 23 67 45 11 89 #Iterate the loop for 5 times do echo "The value of i = $i" #Print each iteration value done |
| While loop It is used as the alternative of for loop. Example: n=10 #Initialize a number while [ $n -le 20 ] #Iterate the loop until the value reaches to 20 do echo "n=$n" #Print the current value of $n n=$(( $n + 5 )) #Increment the value of $n by 5 done |
| Function It is used to define a block of code with a name that can be executed anytime by calling the function name. Example: function_name() { #Define the function echo "Hello World" } echo $(function_name) #Call the function |
| eval It is used to execute arguments like a shell command. Example: c1=$(( 10 + 15 )) #Define the argument c2="echo " #Define the second argument eval $c1 $c2 #Execute the arguments |
| set It is used to control certain flags and features in Bash to set the behavior of the scripts. Examples: set –C #Disable the feature of overwriting the file set –e #Stop script immediately when an error occurs |
| unset Ii is used to delete the variables during the program execution. It can be used to delete both functions and shell variables. Example: var="Hello World" #Assign String value echo $var #Print the assigned variable unset $var #Unset the variable echo $var #Print the variable after unset |
