An A-Z Index of the Bash command line for Linux

  alias    Create an alias
 apropos  Search Help manual pages (man -k)
 apt-get  Search for and install software packages (Debian)
 aspell   Spell Checker
 awk      Find and Replace text, database sort/validate/index
b
 bash     GNU Bourne-Again SHell
 bc       Arbitrary precision calculator language
 bg       Send to background
 break    Exit from a loop
 builtin  Run a shell builtin
 bzip2    Compress or decompress named file(s)
c
 cal      Display a calendar
 case     Conditionally perform a command
 cat      Display the contents of a file
 cd       Change Directory
 cfdisk   Partition table manipulator for Linux
 chgrp    Change group ownership
 chmod    Change access permissions
 chown    Change file owner and group
 chroot   Run a command with a different root directory
 chkconfig System services (runlevel)
 cksum    Print CRC checksum and byte counts
 clear    Clear terminal screen
 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
 cron     Daemon to execute scheduled commands
 crontab  Schedule a command to run at a later time
 csplit   Split a file into context-determined pieces
 cut      Divide a file into several parts
d
 date     Display or change the date & time
 dc       Desk Calculator
 dd       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
 dmesg    Print kernel & driver messages
 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
 expect   Automate arbitrary applications accessed over a terminal
 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
 grep     Search file(s) for lines that match a given pattern
 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)
 history  Command History
 hostname Print or set system name
i
 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
j
 join     Join lines on a common field
k
 kill     Stop a process from running
 killall  Kill processes by name
l
 less     Display output one screen at a time
 let      Perform arithmetic on shell variables
 ln       Make links between files
 local    Create variables
 locate   Find files
 logname  Print current login name
 logout   Exit a login shell
 look     Display lines beginning with a given string
 lpc      Line printer control program
 lpr      Off line print
 lprint   Print a file
 lprintd  Abort a print job
 lprintq  List the print queue
 lprm     Remove jobs from the print queue
 ls       List information about file(s)
 lsof     List open files
m
 make     Recompile a group of programs
 man      Help manual
 mkdir    Create new folder(s)
 mkfifo   Make FIFOs (named pipes)
 mkisofs  Create an hybrid ISO9660/JOLIET/HFS filesystem
 mknod    Make block or character special files
 more     Display output one screen at a time
 mount    Mount a file system
 mtools   Manipulate MS-DOS files
 mv       Move or rename files or directories
 mmv      Mass Move and rename (files)
n
 netstat  Networking information
 nice     Set the priority of a command or job
 nl       Number lines and write files
 nohup    Run a command immune to hangups
 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
 ping     Test a network connection
 pkill    Stop processes from running
 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
 pwd      Print Working Directory
q
 quota    Display disk usage and limits
 quotacheck Scan a file system for disk usage
 quotactl Set disk quotas
r
 ram      ram disk device
 rcp      Copy files between two machines
 read     read a line from standard input
 readonly Mark variables/functions as readonly
 reboot   Reboot the system
 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 keyboard input
 seq      Print numeric sequences
 set      Manipulate shell variables and functions
 sftp     Secure File Transfer Program
 shift    Shift positional parameters
 shopt    Shell Options
 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
 ssh      Secure Shell client (remote login program)
 strace   Trace system calls and signals
 su       Substitute user identity
 sudo     Execute a command as another user
 sum      Print a checksum for a file
 symlink  Make a new name for a file
 sync     Synchronize data on disk with memory
t
 tail     Output the last part of files
 tar      Tape ARchiver
 tee      Redirect output to multiple files
 test     Evaluate a conditional expression
 time     Measure Program running time
 times    User and system times
 touch    Change file timestamps
 top      List processes running on the system
 traceroute Trace Route to Host
 trap     Run a command when a signal is set(bourne)
 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
 unset    Remove variable or function names
 unshar   Unpack shell archive scripts
 until    Execute commands (until error)
 useradd  Create new 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
 watch    Execute/display a program periodically
 wc       Print byte, word, and line counts
 whereis  Report all known instances of a command   
 which    Locate a program file in the user's path.
 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)
 yes      Print a string until interrupted
 .        Run a command script in the current shell
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