Linux Quick Reference Guide

File Commands

Command	Description
`ls`	directory listing
`ls -la`	formatted with hidden files
`mkdir dir`	create a directory dir
`cd dir`	change directory into dir
`cd`	change to your home directory
`pwd`	show current directory
`rm file`	remove the file named file
`rm -r dir`	remove directory dir
`cp file1 file2`	copy file1 to file2
`cp -r dir1 dir2`	copy dir1 to dir2 ; create dir2 if it doesn't exist
`mv file1 file2`	rename or move file1 to file2 - if file2 is an existing directory, moves file1 into directory file2
`ln -s file link`	create symbolic link link to file
`touch file`	create file
`more file`	output the contents of file
`head file`	output the first 10 lines of file
`tail file`	output the last 10 lines of file
`tail -f file`	output the contents of file as it grows, starting with the last 10 lines

Command	Description
ssh user@hostname	connect to hostname as user
ssh -X user@hostname	connect to hostname as user and enable X11 (Display) forwarding

Command	Description
`ps`	display your currently active processes
`top`	display all running processes
`kill pid`	kill process id pid
`killall proc`	kill all processes named proc*
`bg`	lists stopped or background jobs; resume a stopped job in the background
`fg`	brings the most recent job to the foreground
`fg n`	brings job n to foreground

Command	Description
`ping hostname`	ping hostname and show results - use to check if your system can communicate with hostname
`dig domain`	get DNS information for domain
`wget http://foo.com/bar/file.tar.gz`	Download file.tar.gz

Command	Description
`date`	show the current date and time
`cal`	show this months calender
`uptime`	tell how long the system has been running
`w`	show who is logged on to the system
`whoami`	who you are logged in as
`finger user`	display information about user
`uname -a`	show kernel information
`cat /proc/cpuinfo`	show CPU information
`cat /proc/meminfo`	show memory information
`man command`	show manual for command
`df -h`	show disk usage
`du -h file`	show disk usage by file
`free`	show memory and swap usage
`whereis app`	show possible locations of app
`which app`	show which app will be run by default

Command	Description
`Ctrl+C`	halts the current command
`Ctrl+Z`	stops the current command - resume in the background with bg and in the foreground with fg
`Ctrl+D`	exits the current sessioin; similar to exit
`Ctrl+W`	erase one word on the current line
`Ctrl+U`	erase the whole line
`Ctrl+R`	type to bring up a recent command
`!!`	execute the last command
`exit`	exit the current session

Command	Description
`grep pattern files`	search for pattern in files
`grep -r pattern dir`	search recursively for pattern in dir
`command \| grep pattern`	search for pattern in the output of command
`locate file`	locate all instances of file
`find . -name "pattern"`	find filename which matches pattern in the current directory indicated by the . (dot)