Linux Cheat Sheet

In this tutorial, we will list various practical Linux commands to be used only as a reference guide and by experienced Linux users. Not all Linux commands will be available on your system by default so consider installing the relevant package before use.

This Practical Guide to Linux Commands may list Linux commands you already know but cannot remember usage syntax as well as it may introduce some new Linux commands to improve your Linux command line efficiency. Note, this guide will not teach you how to use Linux commands since it relies on your experience to alter Linux commands syntax below to fit your needs.

In this tutorial you will learn:

Linux Cheat Sheet

Software Requirements and Linux Command Line Conventions
Category	Requirements, Conventions or Software Version Used
System	Any Linux distro
Software	N/A
Other	Privileged access to your Linux system as root or via the `sudo` command.
Conventions	# – requires given linux commands to be executed with root privileges either directly as a root user or by use of `sudo` command $ – requires given linux commands to be executed as a regular non-privileged user

Backup and compression

Command	Description
`tar -c scripts/ \| bzip2 -9 > scripts.tar.bz2`	This linux command will use tar and bzip2 to compress scripts directory with a maximum compression
`dd if=/dev/sda1 \| gzip -c9 > /media/usb/sda1.dd.gz`	Backup and compress partition /dev/sda1 to a local file sda1.dd.gz
`cat /media/usb/sda1.dd.gz \| gzip -d \| dd of=/dev/sdX1`	Restore a compressed /dev/sda1 partition backup from a file to a /dev/sdX1 partition
`dd bs=1M if=/dev/sda \| gzip -c9 \| ssh user@linuxconfig.org 'dd of=sda.dd.gz'`	Make a compressed backup of a hard drive /dev/sda and create a remote copy using ssh
`find /etc/ -name '*.conf' \| tar -c --files-from=- \| bzip2 -9 > system_confs.tar.bz2`	Find and compress all configuration files ( *.conf ) located in /etc/ directory into a file called system_confs.tar.bz2
`dd if=/dev/sdb of=my.mbr bs=466 count=1`	Backup and store a Master Boot Record of hard drive /dev/sdb into a file my.mbr
`dd if=my.mbr of=/dev/sdX bs=466 count=1`	Restore a Master Boot Record from my.mbr file to hard drive /dev/sdX
`wget --mirror https://example.com`	Create a complete mirror of a remote website with wget command
`tar cvjf etc_$(date +%Y%m%d).tar.bz2 /etc/`	Create an archive of /etc/ directory using tar command and compress it with bzip2. Compressed file will contain a current date within a filename.
`tar xvjf etc.tar.bz2`	Uncompress a bzip2 archive etc.tar.bz2
`find /var/www/ -name '*.gif' \| xargs cp -va --target-directory=/tmp/gifs`	Find all GIF files ( *.gif ) in /var/www/ and copy them to /tmp/gifs directory.
`ssh user@linuxconfig.org '( mysqldump --password='pass' data > data.sql )'`	Remotely create a mysql database backup of data database into remote file data.sql
`split -b 1000m linux-commands.iso`	Split a file linux-commands.iso into 1GB files. This will produce xaa, xab, xac.. files each of max size 1GB. Can be handy when working with FAT32 filesystem. See below on how to restore split file.
`cat xa* > linux-commands.iso`	Restore a split file back into linux-commands.iso. See above on how to split file.

Searching the filesystem

Command	Description
`find /opt -name 'pass*' -or -size +1000k`	Find all files within /opt directory where file name start with pass or file size is 1000k or more. Feel free to use other boolean operators like AND and NOT.
`locate -r '[^/]*\.conf'`	Search index and locate all files with *.conf extension. You may need to run updatedb first.
`find /home/lilo/ -type f ! -perm 755`	Search for all files in /home/lilo which do not have permissions 755
`find /home/lilo/ -type f -perm 777`	Search for all files in /home/lilo with a permissions 777
`ls -ltr`	List all files in a current directory sorted by access/creation time
`find /tmp/ -mmin -20`	Find all files within /tmp created within last 20 minutes
`find /tmp -iname file -exec chmod 777 {} \;`	search for a file named file ( case insensitive ) and change its permissions to 777
`find /var/log/ -size 8k`	Search for files int /var/log with size of 8k
`find / * -perm +6000 -type f -exec ls -ld {} \; > setuid.txt`	Create a list setuid.txt containing names of all binary files with setuid and setguid

Networking

Command	Description
`curlftpfs ftp-user:ftp-pass@remote.ftp.com /mnt/my_ftp/`	Mount remote ftp server to a local filesystem /mnt/my_ftp/
`ssh user@ssh-server.com '( cd /tmp/ && touch ssh_file.txt )'`	Execute commands remotely using ssh.
`ssh user@ssh-server.com '( cat /etc/passwd )' > /tmp/passwd`	create a local copy of remote /etc/passwd
`airodump-ng -c 6 -w data-capture wlan0`	sniffing wireless network packets using wlan0 wireless interface
`macchanger -r eth0`	Create a fake MAC address for an eth0 network interface
`ssh -L 4500:127.0.0.1:23 linuxconfig.org`	Create a ssh tunnel for telnet using local port 4500
`ssh -L 8025:mail.sample.org:25 mail.sample.org`	Tunnel traffic from a local system port 8025 to port mail.sample.org on port 25
`lsof -i tcp:22`	Displays a service which uses port 22
`ethtool eth0`	Show status of eth0 network interface
`iwlist wlan0 scanning`	Scan for available wireless networks using wlan0 interface
`netstat -ant`	List all TCP ports on the system
`netstat -tupl`	List all available services on the system
`ip route add default via 10.10.10.10`	Set a default route via 10.10.10.10

Arithmetics and conversions

Command	Description
`echo $((0xFFF))`	Convert hexadecimal number ( in this case FFF ) to decimal using shell expansion.
`echo $((8#44))`	Convert octal number ( in this case 44 ) to decimal using shell expansion.
`echo "obase=16; ibase=10; 555;" \| bc`	Convert decimal number ( in this case 555 ) to hexadecimal using shell expansion.
`echo "obase=8; ibase=10; 64;" \| bc`	Convert decimal number ( in this case 64 ) to octal using shell expansion.
`echo "obase=16; ibase=8; 255;" \| bc`	Convert octal number ( in this case 255 ) to hexadecimal using shell expansion.
`echo "3447.2 * 343.61" \| bc`	Multiply a number. For addition and subtraction use “+” and “-” instead of “*”
`echo "scale=10; 100 / 3" \| bc`	Divide number with a floating point precision 10
`units -t '13miles' 'km'`	Convert miles to kilometers ( eg. 13 miles )
`units -t '10.5inches' 'cm'`	Convert inches to centimeters ( eg. 10.5 inches )
`units -t '78344352ms' 'hour'`	Convert milliseconds to hours

Text manipulation

Command	Description
`dd if=commands.txt of=commands.new conv=lcase`	Convert all characters from Uppercase to Lowercase This will not alter a source file, but create new file called commands.new
`rename 's/\.sh$/.bash/' *.sh`	Rename all files in a current working directory with extension .sh to .bash
`rename 's/^/new_/' *.conf`	Add a prefix new_ to all files in a current working directory with extension *.conf
`grep -v ^\# /etc/ntp.conf \| grep .`	Show only uncommented lines within a configuration file as well as ingnore empty lines.
ls \| grep " " \| while read -r f; do mv "$f" `echo $f \| tr ' ' '_'`; done	Remove space from all filenames in a current working directory
ls \| while read -r f; do mv "$f" `echo $f \| tr '[A-Z]' '[a-z]'`; done	Change all filenames in a current directory from uppercase to lowercase.

Date and Time

Command	Description
`date -ud@1244763573`	Convert an epoch time to Coordinated Universal Time
`date -d "Dec 23 18:10:02 EST 2010" +%s`	Convert date to an epoch time
`echo 'wget -c http://linux.com/distro.iso' \| at 03:00`	Download an iso image at 3AM. -c allows you to continue download in case of lost network connection.
`date -d '2 Feb 2013' +%A`	What day would be/was 2 Feb 2013? …Saturday
`units -t '10 days + 6 hours + 26 minutes + 59 seconds' 'seconds'`	Convert time to seconds

Multimedia

Command	Description
`wodim --devices`	Get a burner block device filename
`cdrecord -v blank=all dev=/dev/scd0`	Erase / full blank your cd-rw. Note: use wodim –devices to get your block device file name.
`cdrecord -v blank=fast dev=/dev/scd0`	Erase fast your cd-rw. Note: use wodim –devices to get your block device file name.
`fmpeg -i out.wav -acodec libmp3lame out.mp3`	Convert WAV audio format to MP3
`normalize-mp3 *.mp3`	Normalize a volume for all your MP3 audio files to reduce sudden volume spikes between tracks.
`cat file1.mp3 file2.mp3 > out.mp3`	Join all MP3 audio files into a single track.
`sox file1.wav file2.wav file3.wav out.wav`	Join all wav audio files into a single track.
`for i in $( ls ); do ffmpeg -i $i $i.wav; done`	Convert all MP3 or AC3 audio files into WAV format.
`normalize-audio -m *.wav`	Normalize a volume for all your WAV audio files to reduce sudden volume spikes between tracks.
`cdrecord -v -nofix -eject dev='/dev/scd0' -audio -pad *.wav`	Burn all WAV audio files on a CD using device /dev/scd0
`cdrecord -v -fix -eject dev='/dev/scd0'`	Close a CD session using /dev/scd0 burning device.
`ffmpeg -f x11grab -s xga -r 25 -i :0 -sameq screen.mpg`	Record a video of your screen into a screen.mpg video file.
`for i in $( ls *.jpg ); do convert -resize 25% $i new_$i; done`	Resize all images in your current directory ( in this case images with extension *jpg ) to a 25% of the original size.
`mkisofs -o /tmp/cd.iso /path/to/your/files/`	Create an ISO image from files in /path/to/your/files/
`wodim -eject -tao speed=0 dev=/dev/scd0 -v -data /my/image.iso`	Burn an ISO image using wodim and /dev/scd0 burning device.
`mount -t iso9660 /path/to/iso/file.iso /mnt/iso -o loop`	Mount ISO image to a /mnt/iso directory.
`xrandr --output VGA --auto`	Clone a video output to yout VGA port. Useful for presentations. Use xrandr with no arguments to see whether VGA is connected to a projector.
`arecord -d 10 /tmp/out.wav`	Test your microphone.

Disk Usage and Administration

Command	Description
`time dd if=/dev/hdb of=/dev/null bs=1024k`	Non-destructive hard drive speed and size test. Replace /dev/hdb with your hard drive.
`du -m --max-depth 1 \| sort -rn \| head -11`	Get a directory size of all directories in a current working directory, sort them and show first 10 largest. Note: the first directory is a parent directory.
`du -s * \| sort -k1,1rn \| head`	Display top 10 largest files or directories in a current working directory.
`dd if=/dev/zero of=/sp bs=10000 count=10000; mkswap /sp; swapon /sp`	Create a file /sp with size of 100MB, generate swap signature and include /sp file into overall system’s swap memory. This will add another 100MB to your system’s swap.
`dpkg-query -Wf='${Installed-Size;10}\t${Package}\n' \| sort -k1,1rn`	DEB package management only. Show all installed packages and sort them from largest to smallest.
`rpm -q -a --qf '%10{SIZE}\t%{NAME}\n' \| sort -k1,1rn`	RPM package management only. Show all installed packages and sort them from largest to smallest.
`head -c 100000000 /dev/urandom > file.data`	Create a file.data with a random data and approximately with 100MB in size.
`dd bs=1 seek=2TB if=/dev/null of=~/large-file`	Create a 2TB ~/large-file taking no space.
`df -h .`	Information about free space for a partition located under your current working directory.

Hardware information

Command	Description
`biosdecode`	Retrieve BIOS information.
`dmidecode -s bios-vendor`	Retrieve your BIOS vendor
`dmidecode --type baseboard`	Retrieve information about your motherboard
`ls -la /dev/disk/by-id/usb-*`	USB disk device files. NOTE: USB disk must be plug-in. May not work on all systems.
`hdparm -I /dev/sdx`	Hard drive model of /dev/sdx.
`hdparm -tT /dev/sdx`	Hard drive speed. NOTE: this test disregards a filesystem.
`hddtemp /dev/sda`	Check temperature of /dev/sda hard drive
`lspci \| grep VGA`	Get information about your graphic card
`dmidecode --type 4`	Retrieve your processor information. Also try cat /proc/cpuinfo
`x86info -a 2> /dev/null \| grep Connector \| uniq`	Retrieve a processor socket type. For this to work you need to have a x86info command available. Try install x86info package.
`dmidecode -t 17`	Detect number of RAM slots used, their speed and size. Also try: lshw -C memory -short
`cat /dev/sndstat`	Check your sound card settings and module in use.
`powersave -b`	Get a battery information.
`free -m`	Check system’s free memory. This includes swap memory. Alternatives are: top, cat /proc/meminfo
`fdisk -l \| grep GB`	Check a size of all hard drives including USB.

Tips & Tricks

Command	Description
`head -c 4 /dev/urandom \| mimencode`	Generate 8 random characters. NOTE: mimencode is part of metamail package
`echo "DISPLAY=$DISPLAY xmessage -center 'abc'" \| at "NOW +1hour"`	Display a GUI message in the center of your screen in hour from now.
`:(){ :\|:& };:`	Fork Bomb. Simple way to crash your system.
`ccrypt mypasswords.txt`	Encrypt a file.
`ccdecrypt mypasswords.txt.cpt`	Decrypt a previous encrypted file with ccrypt.

Closing Thoughts

Feel free to reference this cheat sheet any time that you need a quick refresher. The goal here is to save you as much time as possible when trying to remember a certain command.

Two more commands that every user should know are the man command and apropos command. Knowing these two commands, which are very simple to use, will allow you to look up all the options that go with certain commands. apropos also works well as a manual search utility so you don’t need to leave your terminal very often.