File/Directory Basics -

mkdir Making Directory
cd Change the Directory
clear Clear Commands
pwd Present Working Directory
date Display Date
who am I Display the user name
rm Delete files
ls list files
cp Copy files CP <source-path> <destination-path>
mv Renaming the files mv <source-path> <renaming-path>
ln Link files
rmdir Remove directory

File Viewing Commands -

cat View files
less page through files
head view file from beginning (1st 10 records will be displayed)
tail view file ending (last 10 records will be displayed)
nl displays number of lines
od view the binary data
xxd view hexa binary data
gv view post script/pdf files
xdvi view text dvi files

File Creation & Editing -

emacs text editor
pico text editor
vi text editor
umask set default file protections
abiword edit word documents
gnumeric edit excel documents

File properties -

stat display file attributes
wc count bytes/words/lines
du measure disk usage
file identify file types
touch change the file stamps
chown change the file owner
chgrp change the file group
chmod change file protections
chattr change advance file attributes
lsattr list advance file attributes

File Searching -

find locate files
s locate locate files via index
which locate commands
whereis locate standard files

File text manipulation -

grep search text for matching lines
cut extract columns
paste append columns
tr translate characters
sort sort lines
uniq locate identical lines
tee copy stdin to a file and to stdout simultaneously

File compression -

gzip compress files (GN Zip)
compress compress files(unix)
bzip2 compress files(bzip2)
zip compress files(windows zip)

File comparison -

diff compare files line by line
comm compare sorted files
cmp compare files byte by byte
md5sum compute check sums

Spelling operations -

look lookup spelling
aspell check spelling interactively
spell check spelling in batch

Disk and file systems -

df show free space
mount make a disk available
fsck check the disk for errors
sync flush disk caches

Backups and remote storage -

mt control a tape device
dump backup a disk
restore restore a dump
tar read/write tape archives
cd record burn a cd
rsync mirror a set of files

Printing -

lpr print files
lpq view print queue
lprm remove print jobs

Audio & video -

grip play CDs & ripmp3
xmms Play Audi files

Processes -

ps List all processes
w List user’s processes
uptime view the system load
top monitor processes
xload monitor system load
free display free memory
kill terminate process
nice Set process priorities
renice change process priorities

Scheduling jobs -

sleep wait for some time
watch run programs at set intervals
at schedule a job
crontab Schedule repeated jobs

Hosts -

uname print the system information
hostname print the system’s hostname
ifconfig set/display network information
host lookup DNS
who is lookup domain registrants.
Ping check if the host is reachable
Trace route view network path to host

Networking -

Ssh securely login into remote hosts
telnet log into remote hosts
scp securely copy files between hosts
sftp securely copy files between hosts
ftp copy the files between shots
evolution GUI email client
mutt text-based email client
mail minimal email client
Mozilla web browser
Lynx text only web browser
Wget retrieve web pages to disk
Srln read UseNet news
Gaim instant messaging/IRC
Talk linux/unix chat
Write send mesgs to terminal
Mesg prohibit talk/write