LINUX SHELL/TERMINAL CHEAT SHEET

Shell Cheat Sheet linuxadminhelp.blogspot.in

Useful Editing Keystrokes for shell
KEYSTROKE(s)	FUNCTIONS
Up	Move back one command in the history list
Down	Move forward one command in the history list
Left	Move back one character.
Right	Move forward one character
Esc + f	Move forward one word
Esc + b	Move forward one word
Ctrl + A	Move to the beginning of line
Ctrl + E	Move to the end of line
Ctrl + D	Delete current character
Backspace	Delete previous character
Esc + d	Delete current word
Ctrl + U	Delete from beginning of line
Esc + k	Delete to end of line
Ctrl + Y	Retrieve last item deleted
Esc	Insert last word of previous command
Ctrl + L	Clear the screen, placing the current line at the top of the screen
Tab	Attempt to complete the current word, interpreting it as a filename, username, variable name, hostname, or command as determined by the context
Esc + ?	List the possible completions
Ctrl + C	Sends an interrupt signal to the currently executing command, which generally responds by terminating itself
Ctrl + D	Sends an end of file to the currently executing command. Use this keystroke to terminate console input
Ctrl + Z	Suspends the currently executing program
exit	Exit from shell
Shell special characters
CHARACTER	FUNCTIONS
#	Marks the command as a comment, which the shell ignores
;	Separates commands, letting you enter several commands on a single line
&	Placed at the end of a command, causes the command to execute as a background process, so that a new shell prompt appears immediately after the command is entered
()	execute commands in subshell
{}	execute commands in current shell
$var	Substitue the declare variable with its value while execution of the command
special characters used in filename globbing(filename metacharacters)
METACHARACTER	FUNCTIONS
*	Matches a string of zero or more characters
?	Matches exactly one character
[ abc ...]	Matches any of the characters specified
[ a - z ]	Matches any character in the specified range
[! abc ...]	Matches any character other than those specified
[! a - z ]	Matches any character not in the specified range
~	The home directory of the current user
~ userid	The home directory of the specified user
~+	The current working directory
~-	The previous working directory
SHELL ALIASES
alias name='command' (like --> alias mv='mv -i')		unalias <alias name>
special scripts
SCRIPT	FUNCTIONS
/etc/profile	Executed when the user logs in
~/.profile	Executed when the user logs in
~/.bashrc	Executed when BASH is launched
~/.bash_logout	Executed when the user logs out
Shell evironment variables
VARIABLE	FUNCTIONS
USER	The user's current username; may differ from the login name if the user executes the su command
DISPLAY	The X display to be used; for example, localhost:0
HOME	The absolute path of the user's home directory
HOSTNAME	Internet name of the host
LOGNAME	The user's login name
MAIL	The absolute path of the user's mail file
PATH	The search path
SHELL	The absolute path of the current shell
TERM	The terminal type
printenv	Print environment values
export <variable>	To make the value of a shell variable availabl e to the programs invoked by the shell
Variable=	To remove the value associated with shell variable, give the variable an empty value (though it will appear in the output of set cmd)
Unset <variable>	To dispense the variable from the shell
CONTROLLING OPERATION OF THE Shell
CHARACTER	FUNCTIONS
'	Characters within a pair of single quotes are interpreted literally; that is, their metacharacter meanings (if any) are ignored. Similarly, the shell does not replace references to shell or environment variables with the value of the referenced variable
“	Characters within a pair of double quotes are interpreted literally; that is, their metacharacter meanings (if any) are ignored. However, the shell does replace references to shell or environment variables with the value of the referenced variable
` `	Text within a pair of back quotes is interpreted as a command, which the shell executes before executing the rest of the command line. The output of the command replaces the original back-quoted text
\	The following character is interpreted literally; that is, its metacharacter meaning (if any) is ignored. The backslash character has a special use as a line continuation character. When a line ends with a backslash, the line and the following line are considered part of a single line
Input/Output Redirection and Piping (stdin,stdout,stderr)
REDIRECTOR	FUNCTIONS
cmd > file	Redirects standard output stream to specified file (same as cmd 1> file)
cmd 2> file	Redirects standard error stream to specified file
cmd >> file	Redirects standard output stream to specified file, appending output to the file if the file already exists
cmd 2>> file	Redirects standard error stream to specified file, appending output to the file if the file already exists
cmd &> file	Redirects standard output and error streams to the specified file
cmd > file 2>&1	Another way to redirect both stdout and stderr of cmd to a file
cmd < file	Redirects standard input stream to the specified file
cmd << text	Reads standard input until a line matching text is found, at which point end of file is posted
cmd > /dev/null	Discard stdout of cmd
cmd 2> /dev/null	Discard stderr of cmd
cmd &> /dev/null	Discard stdout and stderr of cmd
{ cmd1; cmd2; } > file	Redirect stdout from multiple commands to a file
cmd << EOL line1 line2 EOL	Redirect a bunch of lines to the stdin. If 'EOL' is quoted, text is treated literally. This is called a here-document
cmd1 | cmd2	Takes the standard input of cmd2 from the standard output of cmd1 (also known as the pipe redirector)
cmd1 |& cmd2	Redirect stdout and stderr of cmd1 to stdin of cmd2 (bash 4.0+ only)
cmd | tee file	Redirect stdout of cmd to a file and print it to screen

A cheat sheet by Shiwang Kalkhanda (shiwangkalkhanda@gmail.com) 2012.

http://linuxadminhelp.blogspot.in

Released under GNU Free Document License

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