Cli – Commonly used commands

File Commands

Command	Action
`ls`	directory listing
`ls -al`	formatted listing with hidden files
`cd dir`	change directory to dir
`cd`	change to home
`pwd`	show current directory
`mkdir dir`	create a directory dir
`rm file`	delete file
`rm -r dir`	delete directory dir
`rm -f file`	force remove file
`rm -rf dir`	force remove directory dir*
`cp file1 file2`	copy file1 to file2
`cp -r dir1 dir2`	copy dir1 to dir2, create dir2 if doesn’t exist
`mv file1 file2`	rename or move file1 to file2, if file2 is an existing directory, move file1 into directory file2
`ln -s file link`	create symbolic link link to file
`touch file`	create or update file
`cat > file`	Places standard input into 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	Action
`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 command
`locate file`	find all instances of file

Command	Action
`ps`	display your currently active processes
`top`	top
`kill pid`	kill process id pid
`killall proc`	kill all processes named proc (use with extreme caution)
`bg`	lists stopped or background jobs; resume a stopped job in the background
`fg`	bring the most recent jo to foreground
`fg n`	brings job n to the foreground

Command	Action
`Ctrl+C`	halts the current command
`Ctrl+Z`	stops the current command, resume with `fg` in the foreground or `bg` in the background
`Ctrl+D`	log out of current session, similar to exit
`Ctrl+W`	erase one word in the current line
`Ctrl+U`	erase the whole line
`Ctrl+R`	type to bring up a recent command
`!!`	repeats the last command
`exit`	log out of current session

Command	Action
date	show the current date and time
`cal`	show this month’s calendar
`uptime`	show current uptime
`w`	display who is online
`whoami`	who you are logged in as
`finger user`	display information about user
`uname -a`	show kernel information
`cat /proc/cpuinfo`	cpu information
`cat /proc/meminfo`	memory information
`man command`	show the manual for command
`df`	show disk usage
`du`	show directory space usage
`free`	show memory and swap usage
`whereis app`	show possible location of app
`which app`	show which app will be run by default

Command	Action
`tar cf file.tar files`	create a tar named file.tar containing files
`tar xf file.tar`	extract the files from file.tar
`tar czf file.tar.gz` `files`	create a tar with Gzip compression
`tar cjf file.tar.bz2`	create a tar with Bzip2 compression
`tar xjf file.tar.bz2`	extract a tar using Bzip2
`gzip file`	compresses file and renames it to file.gz
`gzip -d file.gz`	decompresses file.gz back to file
`tar xzf file.tar.gz`	extracting a tar using Gzip

Command	Action
`ping host`	ping host and output results
`whois domain`	get whois information for domain
`dig domain`	get DNS information for domain
`dig -x host`	reverse lookup host
`wget file`	download file
`wget -c file`	continue a stopped download

Command	Action
`chmod octal file`	change the permission of file to octal, which can be found separately for user, group, and world by adding: 4 – read (`r`) 2 – write (`w`) 1 – execute (`x`) Examples: `chmod 777` – read, write, execute for all `chmod 755` – `rwx` for owner, `rx` for group and world for more options, see `man chmod`