Useful Linux commands

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• Run any Linux command by typing the name of the command (and any switches or parameters that are required) at the prompt.

• Unlike DOS and Windows, Linux commands and file names are case sensitive.

Table B-1 provides a list of useful Linux commands.

Table B-1: Useful Linux commands

Command	Syntax	Description
alias		Assign name to specified command list
cat	cat file1	Type or display files
cd	cd /home/user cd ..	Change directory (same as in DOS)
chgrp	chgrp [option] group fname	Change group ownership of file or directory
chmod	chmod [option] mode fname	Change file access permissions
chown	chown [option] owner fname	Change owner of files or directories
cp	cp file1 /dir1/file2	Copy file
crontab		Schedules command to run at regularly specified time
df	df -h	Displays capacity and free capacity on different physical devices. The option -h displays free space in Mb or Gb
du	du directory name	Displays information on disk usage
dir	dir directory name	Display directory listing, same as in DOS
env	env	Display the current environment
file	file <fname>	Determine file type of fname
grep	grep "pattern to search" fname	Used to find a string within a file
id	id	Display userid and groupid
ls	ls ls -l ls -l *.ini	Display directory listing, similar to the dir command in DOS
man	man ps	Displays information from online manual
man -k <keyword>	man -k print	Lists all manual and commands that relate to <keyword>
mv	mv file1 /dir1/file2	Move and rename files
pwd	$ pwd	Print working directory
rm	rm filename	Remove the file
su	su - username	Switch user
tail	tail filename	Display last part of the file
tar	tar options {tar-file-name} {dir-name-to-archive}	File compression and archiving utility
w	w	Lists currently logged on users with processing usage
which	which filename	Displays path to command
&	<command> &	Starts command as background process

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