An A-Z Index of the Linux command line

A       & Start a new process in the background   alias Create an alias •   apropos Search Help manual pages (man -k)   apt Search for and install software packages (Debian/Ubuntu)   apt-get Search for and install software packages (Debian/Ubuntu)   aptitude Search for and install software packages (Debian/Ubuntu)   aspell Spell Checker   at Schedule a command to run once at a particular time   awk Find and Replace text, database sort/validate/index B       basename Strip directory and suffix from filenames   base32 Base32 encode/decode data and print to standard output   base64 Base64 encode/decode data and print to standard output   bash GNU Bourne-Again SHell   bc Arbitrary precision calculator language   bg Send to background   bind Set or display readline key and function bindings •   break Exit from a loop •   builtin Run a shell builtin   bzip2 Compress or decompress named file(s) C       cal Display a calendar   caller Return the context of any active subroutine call •   case Conditionally perform a command   cat Concatenate and print (display) the content of files   cd Change Directory   cfdisk Partition table manipulator for Linux   chattr Change file attributes on a Linux file system   chgrp Change group ownership   chmod Change access permissions   chown Change file owner and group   chpasswd Update passwords in batch mode   chroot Run a command with a different root directory   chkconfig System services (runlevel)   cksum Print CRC checksum and byte counts   clear Clear the terminal screen/console (ncurses)   clear_console Clear the terminal screen/console (bash)   cmp Compare two files   comm Compare two sorted files line by line   command Run a command - ignoring shell functions •   continue Resume the next iteration of a loop •   cp Copy one or more files to another location   cpio Copy files to and from archives   cron Daemon to execute scheduled commands   crontab Schedule a command to run at a later time   csplit Split a file into context-determined pieces   curl Transfer data from or to a server   cut Divide a file into several parts D       date Display or change the date & time   dc Desk Calculator   dd Data Duplicator - convert and copy a file, write disk headers, boot records   ddrescue Data recovery tool   declare Declare variables and give them attributes •   df Display free disk space   diff Display the differences between two files   diff3 Show differences among three files   dig DNS lookup   dir Briefly list directory contents   dircolors Colour setup for 'ls'   dirname Convert a full pathname to just a path   dirs Display list of remembered directories   dos2unix Windows/MAC to UNIX text file format converter   dmesg Print kernel & driver messages   dpkg Package manager (Debian/Ubuntu).   du Estimate file space usage E       echo Display message on screen •   egrep Search file(s) for lines that match an extended expression   eject Eject removable media   enable Enable and disable builtin shell commands •   env Environment variables   ethtool Ethernet card settings   eval Evaluate several commands/arguments   exec Execute a command   exit Exit the shell   expand Convert tabs to spaces   export Set an environment variable   expr Evaluate expressions F       false Do nothing, unsuccessfully   fdformat Low-level format a floppy disk   fdisk Partition table manipulator for Linux   fg Send job to foreground   fgrep Search file(s) for lines that match a fixed string   file Determine file type   find Search for files that meet a desired criteria   fmt Reformat paragraph text   fold Wrap text to fit a specified width   for Expand words, and execute commands   format Format disks or tapes   free Display memory usage   fsck File system consistency check and repair   ftp File Transfer Protocol   function Define Function Macros   fuser Identify/kill the process that is accessing a file G       gawk Find and Replace text within file(s)   getopts Parse positional parameters   getfacl Get file access control lists   grep Search file(s) for lines that match a given pattern   groupadd Add a user security group   groupdel Delete a group   groupmod Modify a group   groups Print group names a user is in   gzip Compress or decompress named file(s) H       hash Remember the full pathname of a name argument   head Output the first part of file(s)   help Display help for a built-in command •   history Command History   hostname Print or set system name   htop Interactive process viewer I       iconv Convert the character set of a file   id Print user and group id’s   if Conditionally perform a command   ifconfig Configure a network interface   ifdown Stop a network interface   ifup Start a network interface up   import Capture an X server screen and save the image to file   install Copy files and set attributes   iostat Report CPU and i/o statistics   ip Routing, devices and tunnels J       jobs List active jobs •   join Join lines on a common field K       kill Kill a process by specifying its PID   killall Kill processes by name   klist List cached Kerberos tickets L       less Display output one screen at a time   let Perform arithmetic on shell variables •   link Create a link to a file   ln Create a symbolic link to a file   local Create a function variable •   locate Find files   login Login to the computer   logname Print current login name   logout Exit a login shell •   look Display lines beginning with a given string   lpc Line printer control program   lpr Print files   lprint Print a file   lprintd Delete a print job   lprintq List the print queue   lprm Remove jobs from the print queue   lsattr List file attributes on a Linux second extended file system   lsblk List block devices   ls List information about file(s)   lsof List open files   lspci List all PCI devices M       make Recompile a group of programs   man Help manual   mapfile Read lines from standard input into an indexed array variable •   md5sum Compute and check MD5 message digest   mkdir Create new folder(s)   mkfifo Make FIFOs (named pipes)   mkfile Make a file   mkisofs Create a hybrid ISO9660/JOLIET/HFS filesystem   mknod Make block or character special files   mktemp Make a temporary file   more Display output one screen at a time   most Browse or page through a text file   mount Mount a file system   mtools Manipulate MS-DOS files   mtr Network diagnostics (traceroute/ping)   mv Move or rename files or directories   mmv Mass Move and rename (files) N       nc Netcat, read and write data across networks   netstat Networking connections/stats   nft nftables for packet filtering and classification   nice Set the priority of a command or job   nl Number lines and write files   nohup Run a command immune to hangups   notify-send Send desktop notifications   nslookup Query Internet name servers interactively O       open Open a file in its default application   op Operator access P       passwd Modify a user password   paste Merge lines of files   pathchk Check file name portability   Perf Performance analysis tools for Linux   ping Test a network connection   pgrep List processes by name   pkill Kill processes by name   popd Restore the previous value of the current directory   pr Prepare files for printing   printcap Printer capability database   printenv Print environment variables   printf Format and print data •   ps Process status   pushd Save and then change the current directory   pv Monitor the progress of data through a pipe   pwd Print Working Directory Q       quota Display disk usage and limits   quotacheck Scan a file system for disk usage R       ram ram disk device   rar Archive files with compression   rcp Copy files between two machines   read Read a line from standard input •   readarray Read from stdin into an array variable •   readonly Mark variables/functions as readonly   reboot Reboot the system   rename Rename files   renice Alter priority of running processes   remsync Synchronize remote files via email   return Exit a shell function   rev Reverse lines of a file   rm Remove files   rmdir Remove folder(s)   rsync Remote file copy (Synchronize file trees) S       screen Multiplex terminal, run remote shells via ssh   scp Secure copy (remote file copy)   sdiff Merge two files interactively   sed Stream Editor   select Accept user choices via keyboard input   seq Print numeric sequences   set Manipulate shell variables and functions   setfacl Set file access control lists.   sftp Secure File Transfer Program   sha256sum Compute and check SHA256 (256-bit) checksums   shift Shift positional parameters   shopt Shell Options   shuf Generate random permutations   shutdown Shutdown or restart Linux   sleep Delay for a specified time   slocate Find files   sort Sort text files   source Run commands from a file '.'  •   split Split a file into fixed-size pieces   ss Socket Statistics   ssh Secure Shell client (remote login program)   stat Display file or file system status   strace Trace system calls and signals   su Substitute user identity   sudo Execute a command as another user   sum Print a checksum for a file   suspend Suspend execution of this shell •   sync Synchronize data on disk with memory T       tabs Set tabs on a terminal   tac Concatenate and write files in reverse   tail Output the last part of a file   tar Store, list or extract files in an archive   tee Redirect output to multiple files   test Evaluate a conditional expression   time Measure Program running time   timeout Run a command with a time limit   times User and system times   tmux Terminal multiplexer   touch Change file timestamps   top List processes running on the system   tput Set terminal-dependent capabilities, colour, position   traceroute Trace Route to Host   trap Execute a command when the shell receives a signal •   tr Translate, squeeze, and/or delete characters   true Do nothing, successfully   tsort Topological sort   tty Print filename of terminal on stdin   type Describe a command • U       ulimit Limit user resources •   umask Users file creation mask   umount Unmount a device   unalias Remove an alias •   uname Print system information   unexpand Convert spaces to tabs   uniq Uniquify files   units Convert units from one scale to another   unix2dos UNIX to Windows or MAC text file format converter   unrar Extract files from a rar archive   unset Remove variable or function names   unshar Unpack shell archive scripts   until Execute commands (until error)   uptime Show uptime   useradd Create new user account   userdel Delete a user account   usermod Modify user account   users List users currently logged in   uuencode Encode a binary file   uudecode Decode a file created by uuencode V       v Verbosely list directory contents ('ls -l -b')   vdir Verbosely list directory contents ('ls -l -b')   vi Text Editor   vmstat Report virtual memory statistics W       w Show who is logged on and what they are doing   wait Wait for a process to complete •   watch Execute/display a program periodically   wc Print byte, word, and line counts   whereis Search the user’s $path, man pages and source files for a program   which Search the user’s $path for a program file   while Execute commands   who Print all usernames currently logged in   whoami Print the current user id and name ('id -un')   wget Retrieve web pages or files via HTTP, HTTPS or FTP   write Send a message to another user X       xargs Execute utility, passing constructed argument list(s)   xdg-open Open a file or URL in the user’s preferred application.   xxd Make a hexdump or do the reverse   xz Compress or decompress .xz and .lzma files   yes Print a string until interrupted   zip Package and compress (archive) files   . Run a command script in the current shell   !! Run the last command again   # Comment / Remark