dvdrecord -scanbus = lists dvd devices
df -h = free hard drive space
df = free hard drive space
du -sh = disk usage
du -h = hard drive usage
dialog –msgbox “Hello” 8 12 = create dialog box
dialog –title “Check me” –checklist “Pick numbers” 12 15 2 1 “First” “on” 2 “Second” “off” = create checklist
echo $SHELL = prints the default shell name
echo $OSTYPE = prints the operating system name
echo ‘text’ = prints what is held in the quotes
echo $HOME = prints home directory
echo $USER = who is currently using the system
echo $HISTFILE = location of history file
echo $HISTFILESIZE = history’s set size
echo $HISTSIZE = history’s set size
echo “test” | mail -v -s test xyz@abc.com = sending e-mail from a terminal
ethtool eth0 = info about ethernet connection
ethtool -i eth0 = driver for ethernet
ethtool -S eth0 = statictics for ethernet
ethtool l0 = info about local loop
egrep “one/two/three” filename = looks for any of these 3 words in a file
env = prints all environment variables
expr 7 + 8 = simple command based calculator (mind the spaces in the equation)
/etc/init.d/httpd status = service status
/etc/init.d/mysqld start = starts mysql server
/etc/init.d/oracle-xe start = starts oracle server
exec ls -l = runs ls command and closes the terminal
exec uptime = runs uptime command and closes terminal
fc -l = short command history
fdisk -l = list of partitions on the hdd
fdisk -l /dev/hda = partitions within a specific partition
fdisk /dev/hda = master device on IDE channel 0
fdisk /dev/hdb = slave device on IDE channel 0
fdisk /dev/hdc = master device on IDE channel 1
fdisk /dev/hdd = slave device on IDE channel 1
find /usr/bin -amin -30 = finds files accessed in last 30 minutes in /usr/bin
find /usr/bin -atime +50 = finds files not accessed for than 50 days
find /usr/bin -perm 750 = finds files with permission 750
find /usr/bin -user root = finds files owned by root in /usr/bin
find /usr/bin -user root | wc -l = calculates total no of files owned by root
find ! /usr/bin -user root = finds files not owned by user root
find ! /usr/bin -user root | wc -l = calculates no of files not owned by root
find -iname filename.ext = finds a file by name
find . = lists all files and subdirectories in the current directory
find . -size +200M = finds files more than 200M in size
find . -size +200M -ls = more details
find . -name *.txt -size +40K = finds .txt file names of more than 40 k in size
find /usr/share/docs | xargs grep -l ‘keyword’ = finds files that contain the keyword from documents
finger = log in details
free = memory usage in kb
free -b = memory usage in mb
free -m = memory usage in blocks
free -mt = memory usage in totals
free -g = memory usage in gigabytes
free -s 5 = update memory usage every 5 seconds
fuser -amuv /boot = shows processes with /boot open (a = all, m = man, u = user, v = verbose)
fuser /boot = shows parent pids for processes opening /boot
fuser -m /boot = shows pids for processes opening /boot
fuser -u /boot = shows pids for user
fuser -k /boot = kills all processes with /boot files open
fuser -l = lists supported signals
fuser -k -HUP /boot = kills all processes running /boot by sending HUP signal
getenforce = status of selinux
gdmsetup = display configuration client/gui
glxinfo = graphics card info
glxinfo | direct = check if direct randering is on
gnome-terminal -x alsamixer = stars terminal with alsamixer displayed
gnome-terminal -tab -tab -tab = stars terminal with 3 open tabs
gnome-terminal -geometry 80*20 = stars terminal 80 characters and 20 lines
gnome-terminal -zoom=2 = stars terminal with larger fonts
grep india /usr/share/dict/words = looks for the word ‘india’ in dictionary
grep “word” filename.txt = prints lines with the “word ” in them
grep –color “word” filename.txt = prints lines with the word in color
grep 300 filename.txt = prints lines with 300 in them
grep -n “word” filename = line numbers with the word in them printed
grep -vn “word” filename = lines without the “word” in them
grep -c “word” filename = total no. of occurrences of “word”
grep -n “word” * = lists all lines from all files that contain “word”
grep -R myword /etc/bin* = lists lines with their file names in the directory containing myword
grep -h -R myword /etc/bin* = lists lines without their file names containing myword
grep -Rn myword /etc/bin* = lists lines containing myword with their numbers
grep –color -R myword /etc/bin* = lists lines in the directory containing myword in color
grep -Rl myword /etc/bin* = lists file names in the directory containing myword
grep -x “word” * = only “word” a line
grep word filename.txt = searchers for the word in the file (case sensitive)
grep word -n filename.txt = lists lines containing word with their numbers
grep -i word filename = searchers for the word in the file (i = not case sensitive)
grep -i word1 word2 filename = searchers for the word in the file
groups = list of groups
gzip = only zips, gunzip = unzips + untars, tar = zips + unzips with czvf, xzvf
gzip abc.txt = zips a file
gzip -1 abc.txt = fast compression but poor quality
gzip -9 abc.txt = slow compression but good quality
gzip -rv foldername = zips all files in the folder
gzip -tv abc.txt.gz = checks integrity if gz file with verbose
gzip -lv abc.txt.gz = gives info about gz file
gunzip -v abc.txt.gz = unzips gz file with verbose
gunzip -c abc.tar.gz | tar x = unzips and untars a file (two steps)
gunzip abc.tar.gz; tar xf abc.tar = unzips then untars a file (two steps)
hal-device-manager = opens a gui for hardware profiling
head -6 .bash_history = first 6 commands
head -5 filename.txt = prints first 5 lines of the file
head -n 5 filename.txt = prints first 5 lines of the file
history 5 = last five commands
history | wc -l = total history commands
history | grep rpm = search through history for rpm commands
history = list of all commands used so far
hostname = name of the host
hwclock –show = prints today’s date and time
hwclock –set –date =”2/22/2008 12:25:30” = reset new time and date
identify imagename.jpg = gives image info
identify -verbose imangename.jpg | less = gives info about image
identify -verbose imangename.jpg | more = gives more info about image
id = info about user/root’s groupid/uid etc
ifconfig = network card info, ipaddress etc.
ifconfig -a = available network cards
info coreutils = info about core commands
iostat 3 = checks disk reads
iostat -c 3 = updates cpu usage
iostat -c -t = cpu usage with time
iostat -c -t 2 10 = repeat cpu usage info every 2 seconds 10 times
ip a = available network interfaces
ip addr = ip addresses by method of connection ie ppp0
ip addr show eth0 = ip address for ethernet connection
ip calc -bnm 192.168.0.1/27 = displays netmast ip from CIDR
ip route = checks routing table
isoinfo = info about iso
iwconfig = checks for wireless connection
iwlist = checks for a wireless access point
kded –version = kde version
kde-config –version = kde version
kill 23456 = kills process with id 23456
kill -9 1234 = sends SIGKILL to id 1234
kill -SIGCONT 1234 = sends SIGCONT to id 1234
kill 4% = kills the process represented by 4% job
kill sttd = kills all sttd daemons running
last = last log in details
lastlog [-u root] = last log in time
last [root] = entire log in history, the feature needs to be activated first
lastb [root] = prints failed login attempts
less filename.txt = prints contents of the file, scroll bar fixed, Press q to quite and spacebar to go to another page
less filename.txt = prints contents of the file, scroll bar fixed, press spacebar
less filename /word = searches for word
ln -s originalfile newfile = creates a symbolic link to new file
locate xyz = locates file xyz case-sensitive
locate -i xyz = locates file xyz not case-sensitive
locate -r /ls$ = locates files ending in /ls
locate -r james*bond = locate files with james and bond in their names
locate -r ^ boot/grub/me = locate files beginning with boot/grub/me
locate *.jpg > Desktop/myjpgs.txt = stores results of search in a file named myjpgs.txt
lsmod = lists kernel modules installed
lsmod | sort -k 2,2n = sorts kernel modules in increasing size order
ls /var/www/html/*.html = lists all html files
ls .??* = lists all directory names that start with a dot .
ls /etc/rc.d = prints all directories for all available run levels
ls /etc/rc.d/init.d = list of system services’ scripts
ls -l = lists files and folders in the current directory
ls -la = lists hidden files and folders in the current directory with a dot
ls li = files with their inodes
ls -lt = files recently modified
ls -lu = lists files by their accss time
ls -ln = user names and groups numerically displayed
ls -lh = human readable file sizes
ls -lR = displays all the files and their folders
ls -F = lists files by type
ls -c = lists files columnwise
ls –color =always = shows filenames in colors
ls -l /var/lib/rpm = rpm database
ls = lists contents of a directory
ls . = lists contents of a directory
ls .. = lists contents of a directory
ls / = lists all system directories
ls = lists directories in current directory
ls /var = lists all subdirectories under the /var directory
ls /proc | wc -l = number of subdirectories in /proc directory
ls -ltr =
ls -l filename.ext = checks permissions for a file
ls -l /etc = permission status of all subdirectories
ls -a = shows hidden . Dot directories. A kind of special configuration files not be messed with
ls tr | ‘\n’ ‘ ‘ = replaces all newline characters with spaces
ls tr | -d ‘\n’ = deletes newlines
ls /var/lib/mysql = list of databases in blue color
lsof = list of open directories and files
lsof -c bash = list of files open by bash shells
lsof -d cwd = list of directories open as current working directory
lsof -u james = list of files and directories open by user james
lsof /mnt/sda1 = list of anything open on /mnt/sda1 file system
lsof +d /mnt/sda1/dx = list of anything open under /mnt/sda1/dx directory
lpadmin = Linux printer details
lspci = info about pci devices/ports
lspci | grep VGA = graphics card info
lspci | grep audio = audio card info
lspci | grep -i modem = modem info
lspci | grep -i usb = usb ports info
lspci | grep -i ethernet = ethernet card info
man -f php = info about php modules
man -k php = info about php modules
man php = php manual pages
man man = info about manual pages and their format
man 3 php = shows entries for php in 3rd section of the manual
man php | grep word = searches for a particular word in php manual
man hier = info about directories
md5sum xyz.iso = checksum verification
more filename.txt = shows contents of a file page by page (press spacebar)
mount = files system type per device
mount /mnt/cdrom = mounts cd rom
mysql = launches mysql
mysql -u root -p = asks for a password to launch mysql
my old.txt new.txt = renames a file
netstat = info about active Internet connections
netstat -i = netstat statictics
netstat -tanp = shows active tcp connections
netstat -uanp = shows active udp connections
od -c -t x1 filename.txt = list of newline characters in Linux
ogg123 mysong.ogg = plays ogg file
ogg123 http://xyz.com/music/audio.ogg = plays from web address
ogg123 -z *.ogg = play files in pseudo-random order
ogg123 -Z *.ogg = same -z, but repeats forever
ogg123 /var/music/ = plays songs in /var/music and sub dirs
ogg123 -@myplaylist = plays songs from playlist
pgrep httpd = gives process id for httpd
pgrep -l init = gives process id for processes containing init as string
ps -lu james = all processes owned by james
php –help = shows all php help pages in full
php –help | less = shows limited php help pages, scroll bar fixed, q to exit
php -v = php version
php –version = php version
pirut =
passwd = asks for a new password for root
play musicfilename.wav = plays music file
play *.wav = plays all wav files upto 32
play audio.au vol. 6 = plays audio file with volume level 6
play -r 12000 short.aiff = sampling rate of 12000
ps ajfx = process hierarchy in BSD style
ps ax = lists all running processes
ps aux = lists all running processes with BSD cycle
ps auwx = running processes with wide format
ps auwwx = running processes with unlimited width
ps auwx | sort -r -k 4,4 = sort processes on descending memory usage
ps auwx | head -4 = prints first 4 lines of a process
ps auwx | head -n 4 = prints first 4 lines of a process
ps auwx | tail -4 = prints last 4 lines of a process
ps auwx | tail -n 4 = prints last 4 lines of a process
ps auwx | less = shows contents of a process, scroll bar fixed
ps auwx | more = shows contents of a process page by page (press spacebar)
ps auwx | grep init = shows lines containing init in them
ps auwx | grep “\[*\]” = shows bracketed comments
ps = list of processes by current user in current shell
ps -C httpd = process info for http
ps -p 5323 -o pid,ppid,bsdtime,args = process info for id 5323
ps -U james,john -o pid,ruser,tty,stat,args = process info for 2 users
ps -e = lists all running processes
ps -e | wc -l = number of all running processes
ps -ef = lists all running processes with format listing
ps -ef –forest = process hierarchy in forest format
ps -eF = lists all running processes with full format listing
ps -ejH = process hierarchy
ps -el = lists all running processes with long listing
ps -eo ppid,user,%mem,size,vsize,comm –sort=-size = multiple parameters
ps -eo ppid,user,bsdstart,bsdtime,%cpu,args –sort=-%cpu = multiple parameters
ps -eo ppid,user,bsdstart,bsdtime,%cpu,args –sort=-%cpu = multiple parameters
ps -eo ppid,user,stat,tname,sess,cputime,args –sort=user = multiple parameters
pstree = processes in alphabetical order in tree format
ps -u root = list of processes run by user root
ps -u root u = list of processes run by root with cpu usage
ps -fu root = list of processes run by root with PPID
pwd = current working directory
pwd -P = one level up from current working directory
pwd -L = one level down from current working directory
printenv | less = prints all environment variables
ps -ef | grep root = processed owned by root
ramsize = info about ram
reboot = reboots the pc
redhat-logviewer = opens a GUI tool for log monitoring
repoquery -il tomcat5 = list of files in tomcat5 package in any repo
repoquery –provides php = info about php modules
rm ~/.bash_history = clears history of commands
rm -f *.doc = removes/deletes all files of .doc extension in a folder
rpm2cpio xyz.rpm > xyz.cpio = extracts cpio archive from rpm package
rpm2cpio xyz.rpm | cpio -tv = lists the contents of archive
rpm -e xyz = removes package xyz
rpm -e –nodeps xyz-5.6.fc5.i386 = removes 32+ bit version of package if more versions available
rpm -ivh xyz.rpm = install package xyz (i=install, v=verbose, h=hash)
rpm -ivh http://ftp.abc.com/xyz.rpm = install package xyz from the site
rpm -Uvh xyz.rpm = update package xyz (U=update)
rpm -q –scripts kernel |less = list of all preinstall & post-install scripts
rpm -q php = php version no.
rpm -qi php = php install info
rpm -qi fedora-release = Fedora installation info
rpm -qi php/per/python/ruby = version info for the package
rpm -qa grun = prints grub version no.
rpm -qa php = prints php version no.
rpm -qa | sort | pr –column=2 | less = shows installed packages in 2 columns per page
rpm -qa | sort | pr –column=2 > abc.txt = saves output to a file
rpm -qa | sort | pr –column=2 | lpr = sends output to a printer
rpm -qa | grep kernel | sort = sorts installed packages in alphanumeric order
rpm -qa | grep kernel | sort -r = sorts in reverse alphanumeric order
rpm -qa | grep php = prints version nos. of all php related packages
rpm -qa | head = only 10 softwares listed
rpm -qa | head -n5 = first 5 software listed
rpm -qa | wc -l = total no of packages installed on the system
rpm -ql php = lists all files in a particular package
rpm -qal | grep php = find php in all installed packages
rpm -ql php | wc -l = total no. of files in a particular package
rpm -qa | grep php | wc -l = count the total number of php modules
rpm -qf /var/lib/php = what package a particular file belongs to
rpm -q –scripts mysql = scripts of a package
rpm -qa php | wc -l = total no. of php packages
rpm -qi php = info about php
rpm -q –last php = installation date of php
rpm -qi php | grep -i vendor = php vendor name
rpm -qi fedora-release | grep -i vendor = prints vendor name from a file named fedora-release
rpm -v = rpm version
rpm -qa –queryformat ‘%{NAME}==%{VENDOR}\n’ | grep -v “Red Hat” | sort =
list of installed packages with their vendor names except Red Hat
rpm -qa –qf ‘%{NAME}==%{VENDOR}\n’ | grep “Red Hat” | sort = list of installed packages with their vendor name as Red Hat
rpm -qa –qf ‘%{NAME}==%{VENDOR}\n’ | sort = list of installed packages with their vendor names
rpm -qa –qf ‘%{NAME}==%{VENDOR}\n’ | grep “Red Hat” | wc -l = total number of installed packages with Red Hat as their vendor
rpm -qa –qf ‘%{NAME}==%{LICENSE}\n’ | sort = list of all installed packages with their licence type sorted alphabetically
rpm -qa –qf ‘%{NAME}==%{LICENSE}\n’ | wc -l = total number of installed packages with their licence type
rpm -qa –qf ‘%{NAME}==%{LICENSE}\n’ | grep php | sort = list of all php packages with their licence types sorted alphabetically
rpm -qa –qf ‘%{NAME}==%{LICENSE}\n’ | grep php | wc -l = total number of all php packages with their licence types
rpm -qa –qf ‘%{NAME}==%{SIZE}\n’ | sort = list of all installed
packages with their names and sizes in bytes sorted alphabetically
rpm -qa –qf ‘%{NAME}==%{SIZE}\n’ | grep php | sort = list of all php
packages with their names and sizes in bytes sorted alphabetically
rpm -qa –qf ‘%{NAME}==%{SIZE}\n’ | grep php | wc -l = total number of
installed php packages with their names and sizes in bytes
rpm -qa –qf ‘%{NAME}==%{SUMMARY}\n’ | sort = list of all installed
packages with their names and functions sorted alphabetically
rpm -qa –qf ‘%{NAME}==%{SUMMARY}\n’ | grep php | sort = list of all php
packages with their names and functions sorted alphabetically
rpm -qa –qf ‘%{NAME}==%{SUMMARY}\n’ | grep php | wc -l = total number of all php packages with their names and functions
rpm -qa –qf ‘%{NAME}==%{BUILDHOST}\n’ | sort = list of all installed
packages with their names and buildhosts sorted alphabetically
rpm -qa –qf ‘%{NAME}==%{BUILDHOST}\n’ | grep php | sort = list of all
php packages with their names and buildhosts sorted alphabetically
rpm -qa –qf ‘%{NAME}==%{BUILDHOST}\n’ | grep php | wc -l = total number of all php packages with their names and buildhosts
rpm -qa –qf ‘%{NAME}==%{URL}\n’ | sort = list of all installed packages with their names and urls sorted alphabetically
rpm -qa –qf ‘%{NAME}==%{URL}\n’ | grep php | sort = list of all php packages with their names and urls sorted alphabetically
rpm -qa –qf ‘%{NAME}==%{URL}\n’ | grep php | wc -l = total number of all php packages with their names and urls
rpm -qa –qf ‘%{NAME}==%{ARCH}\n’ | sort = list of all installed
packages with their names and architecture type sorted alphabetically
rpm -qa –qf ‘%{NAME}==%{ARCH}\n’ | grep php | sort = list of all php
packages with their names and architecture type sorted alphabetically
rpm -qa –qf ‘%{NAME}==%{ARCH}\n’ | grep php | wc -l = total number of all php packages with their names and architecture type
rpm –querytags = list of all rpm query tags
rpm –querytags | wc -l = total number of rpm tags
rpm -Va = verify all installed packages
rpm -Va | grep php = verify php packages only
rpm -Vv | grep php = check php packages only with verbose
root = superuser, who has permission to do anything
/root = root account’s home directory
sha1sum xyz.iso = checksum verification
stat filename = prints access/modification right to a file
set = list of all enviornmental variables
set | wc -l = total number of enviornmental variables
set history = 60 = history of commands set to 60
set | less = prints all shell variables, scroll bar fixed
setserial -g /dev/ttys0 /dev/ttys1 /dev/ttys2 /dev/tty3 = info about serial ports
setserial -ga /dev/ttys0 = info about one serial port
stty -F /dev/ttys0 -a = info about serial port
service httpd start = starts apache server
service mysqld start = starts mysql server
service –status-all = service status of all the services installed
shutdown = shutdowns the pc
shutdown -r = reboot
shutdown -0 (Zero) = reboot
shutdown – h = halt