Working with File System

Create a File

touch file-name		create 0 sized file
cat > file-name		create file by default
vi file-name		use vi editor

Display File Contents

cat file-name		display contents of file-name
more file-name		display contents per screenfull
less file-name		display contents per screenfull
head file-name		display first 10 lines of file-name
tail file-name		display last 10 lines of file-name

List Files and Directories

ls			list contents of directory
ls -l			list files in long format
ls -a			include "."(dot) files

Copy Files

cp src-file dest-file	copy src-file to dest-file
cp src-file dest-dir	copy a file into a directory
cp -R src-dir dest-dir	copy one directory into another
cp-i src dest		copy & prompt before overwriting


Remove File

rm file-name		remove(delete) a file
rmdir dir		remove an empty directory
rm -r dir		remove directory & contents
rm -i file-name		prompt before removing file

Make a Directory

mkdir directory-name	make a directory


Move(Rename) Files & Directories

mv src-file dest-file	rename src-file to dest-file
mv src-file dest-dir	move file into a directory
mv src-dir dest-dir	rename src-dir,or move,to dest-dir
mv -i src dest		move & prompt before overwriting


Change Directory

cd 				return to login directory
cd dir				change to directory dir
cd..				change to parent of directory


Changing Access Modes

chmod mode-setting file-name	change access permissions
				for file file-name
chmod -R mode-setting dir	change access privileges
				for all files in dir


        Mode Settings
	u   user
	g   group
	o   other(public)
	+   add permission
	-   remove permission
	r   read
	w   write
	x   execute
Example: chmod go +rwx foo.c	adds read write execute
				permissions for group &
				other(public) on foo.c

	Mode Setting
	4	read(r)
	2	write(w)
	1	execute(x)
	ugo	user-group-other	order of numerical
					mode setting

Example: chmod 765 foo.c		read,write,execute permission
					for user, read & write permission
					for group and read & execute
					permission for other on foo.c

Find Path and Name of Directory

pwd				display absolute path of
				present directory
find .-type f -print		search directory & subdirectories
				and list all files
ff file-name			searches dir. & subdir. for file-name


Compress Files

tar cf file.tar files		create a tar file named file.tar
				containing given list of files
tar xf file.tar 		extract files from file.tar
gzip file			compresses file and renames
				it file.gz
gzip -d file.gz			uncompress file.gz back to 'file'
tar czf file.tar.gz files	create tar file with gzip compression
tar xzf file.tar.gz		uncompress and extract files


Directory Abbreviations


~ (tilde)		home directory
~user-name		user-name's home directory
. (dot)			Present directory
..			Parent directory of present directory
../..			Parent of parent directory


Searching

grep string file-name	  	show lines containing 'string'
				in 'file-name'
grep -v string file-name	show lines not containing 'string'
grep -i string file-name	show lines containing 'string'
locate file-name		find all instances of file


Redirection

command > file		direct output of command to 'file'
			instead of standard output(screen)
			replacing contents of file
command >> file		direct output of command to 'file'
			append to current file content
command < file		'command' receives input from file
			instead of standard input(keyboard)
cmd1 | cmd2		"pipe" output of cmd1 to input of cmd2
script file		log everything displayed on terminal
			to 'file'; end with exit


User Information

who			list current users
whoami			who you are logged in as
finger user		display information about 'user'
id user			display information about 'user'
passwd			change your password
quota -v		show your disk space quota
last yourusername	lists your last logins


System Information

df			show disk usage
du			show directory space usage
uname -a		show kernel information
free			show memory and swap usage
whereis app		show location of 'app'
top			show all running processes
date			show current date and time
uptime			show uptime since bootup


Process and Job Management

ps			show active processes and
			pid(process id) numbers
ps gx			include "hidden" processes
jobs			show current jobs and job id numbers
kill pid#		kill process id 'pid'
killall proc		kill all prcesses name 'proc*'
bg			list bacground jobs
fg			bring most recent job to foreground
fg %job-id#		bring job 'job-id' to foreground


Information

man command-name	show online manual pages
man -k string		list one line summaries of man
			pages containing 'string'