Comprehensive Linux Cheatsheet

^{Download text file or Fork me on GitHub.}

Gnome

Ctrl+Alt T	Terminal
Ctrl+Alt F	Firefox
Ctrl+Alt H	Home
Ctrl+Alt G	Gedit
Alt F12	Run command

Alt F1	Minimize window
Alt F2	Toggle maximize window
Alt F3	Toggle full screen
Ctrl+Alt D	Minimize all windows

Ctrl+Alt F1-F6	Terminals (tty-s)
Ctrl+Alt F7-F12	Xwindows
Ctrl+Alt Bksp	Restart X
Ctrl+Alt Del	Log out
Ctrl+Alt End	Shutdown
Super PgUp/PgDn	Switch workspace
Middle mouse button	Paste selected text

Nautilus/Nemo

Ctrl L	Location, show path
Ctrl+Shift N	New folder
Ctrl H	Show hidden files

Gedit

Ctrl G	Find next
Ctrl+Shift G	Find previous
Ctrl+Shift K	Clear highlights

Terminal

Ctrl+Shift C	Copy
Ctrl+Shift V	Paste
Ctrl+Shift T	New tab
Ctrl+Shift W	Close tab
Ctrl PgUp/PgDn	Switch tab
Ctrl +/-	Zoom
Ctrl D	Close terminal
Ctrl S	Scroll lock

Bash

Keys when in emacs mode. You can switch to 'vi' mode with 'set -o vi' command.

Ctrl C	Interrupt, erase line
Ctrl A	Go to beginning of line
Ctrl E	End of line
Ctrl U	Copy line
Ctrl Y	Paste line
Alt .	Last argument
Ctrl R	Search trough history
Alt *	Show all matches for regular expression
Ctrl+Alt E	Show current line passed through alias, history and shell expansion
Ctrl X, Ctrl E	Edit command in editor
Ctrl P	Show last command (same as up arrow)

Awesome Terminal Commands

Packages#

dpkg	Low level package manager for Debian.
	-l Lists installed packages. -i <package> (sudo) Installs package from a package file.
apt-get	Advanced Package Tool built on top of 'dpkg'. New command called simply 'apt' is also available. It merges the functionalities of 'apt-get' and 'apt-cache'.
	update Updates local list of existing packages. -u dist-upgrade Upgrades by intelligently handling changing dependencies with new versions of packages. To regularly update put this line in 'crontab': 'apt-get update && apt-get -u dist-upgrade'. upgrade Same as dist-upgrade, but will not remove installed packages or install new ones. install <package> Also updates single package. remove <package> Removes package but leaves its configurations. remove apt-listchanges Useful when Debian can't find a package. purge <package> Removes package and its configurations. Run 'apt-get autoremove' after to remove all dependencies that are not needed anymore. autoremove Removes unneeded packages. source <package> Downloads code. build-dep <package> Installs the build dependencies. --yes Answers with 'yes' to most questions (Except the ones that can have potentially harmful consequences). --force-yes Answers 'yes' to all questions (Not recommended).
apt-cache	Queries the APT's internal database.
	search <keyword> Searches packages like 'apropos', but globally. show <package> Shows package info like version, dependencies, etc. showpkg <package> Similar, but also shows the packages that depend on the searched package (reverse dependencies). policy <package> Shows installed and remote version.
apt-file	APT package searching utility.
	search <file> Search in which package a file is included. update Updates local list of package contents.
aptitude	Enables package browsing (skin for apt-get).
	search '~i!~M' Lists installed packages that were not installed as a dependency, with short description of each. search <package> Package search.

winetricks	Installs wine applications.
update-alternatives	Maintains symbolic links determining default commands.
unattended-upgrade	Automatic installation of security upgrades.

Commands

apropos <cmd>	Searches the manual page names and descriptions (use quotes for phrases).
	-a Matches all keywords.
whatis <cmd>	Displays one-line manual page description.
whereis <cmd>	Locates the binary, source, and manual page files for a command.
which <cmd>	Locates only the binary of a command.
wtf	Translates acronyms and filename suffixes.

Install Mantra

./configure --help
./configure
make
sudo make install

General#

su	Switches user.
	- <user> Switches to user. - Switches to root.
man	Help on commands.
	<section> Section numbers: 1. Programs, 2. System calls, 3. Library calls, 4. Special files, 5. File formats, 7. Miscellaneous, 8. System administration commands
echo	Prints passed text.
	-n Does not add newline at the end. -e Enables interpretation of backslashed letters.
xargs <cmd>	Passes output from one command to arguments of another: 'echo -a | xargs ls'
	-t Echoes the command before executing it. -p Echoes command and asks for confirmation before execution. -0 Input items are separated by null character instead of space.
tee <file>	Sends output of a program to specified file and to standard output: '<cmd_1> | tee out_1.txt | <cmd_2>'
	/dev/tty Sends output to terminal and to standard output
expr	Evaluates passed expression.
	1 + 1 Prints '2'.
bc	Evaluates input. It's basically a calculator, but also provides some control commands.
	echo 1 + 1 | bc Prints '2'. echo "scale=5;3/4" | bc Prints '.75000'.
sh	Runs command interpreter (shell). Can run a script even if not executable.
	-c '<commands>' Starts new non-interactive shell and reads commands from arguments instead of 'stdin'. To append lines to system configuration file run: 'sudo sh -c 'echo "<text>" >> <file>''
bash	Runs bash command interpreter (shell).
	-c Reads commands from arguments instead of 'stdin'. -n <script> Checks script for errors. -x Prints commands before execution. Useful for debugging.
gcc	Gnu C compiler. Run 'g++' for C++ code.
	-w Supresses warnings (Only prints errors). -Wall All warnings. -g Compile for debugging. -std=<std> Sets the standard. Suported standards for C are: 'c90', 'gnu90', 'c99', 'gnu99', 'c11' and 'gnu11'. Suported standarts for C++ are: 'c++98', 'gnu++98', 'c++11' and 'gnu++11'. 'gnu90' and 'gnu++98' are the default options. -O<level> Optimization level. '0': Reduce compilation time (default), '1-3': - Level of optimization, 's' - Optimize for size, 'g' - Optimize debugging experience.
run-parts <dir>	Runs all scripts or programs in a directory.
date	Tells and sets date and time.
	-s <string> Sets date. +%T -s "10:13:13" Sets time.
timedatectl	Controls the system time and date.
	set-timezone CET Sets timezone.
cal	Calendar
xclip	Copies to clipboard.
mkfifo <pipe>	Creates named pipe during that shell session.
mkisofs	Creates a DVD/CD image.
genisoimage	Creates a DVD/CD image (Debian).
cdrecord	Writes to a CD/DVD.
acpi	Checks battery.
fdisk -l (sudo)	Shows partitions.
shutdown	Closes down the system at a given time.
	now Takes you to the single user mode. -h now Begins the shutdown procedure, same as 'halt' and 'poweroff'. -h 11:50 At 11:50. -r now Same as 'reboot'.
make	Utility that maintains groups of programs.
	-q Doesn't run any commands, just returns '0' exit code if everything is up to date or non-zero otherwise. -B Unconditionally makes all targets.

Files

ls	-d List directory names instead of contents -S Sort by size -t Sort by time -1 One file per line ./* Ls one level deep -i Get inode number of file (file id). Use 'sudo find / -inum <number>' to find all links that point to same file.
cp	-i Interactive (Prompts before overwrite) -v Verbose (Explains what is being done) -R Copy directories recursively -p Preserve mode, ownership and timestamps --preserve=all Also preserves context, links and xattr
rm	-i Interactive (Prompts before every removal) -v Verbose (Explains what is being done) -f Force remove (Does not prompt, useful if 'rm' is aliased with '-i') -R Removes directories and their content recursively
mkdir	-p Make parents if needed
ln	Makes links to the files
	-s <file> <link> Makes symbolic link. If you want to use relative paths you must be in links directory !!!!!!!!!!!!!!!!!!!!!!
df	-h Displays humanly readable free disk space
du	-s <dir> Directory size
mc	Midnight commander
	Alt o Open parent dir in another panel Ctrl o Switch to bash
find <dir>	-name <file> Search by name -regex <regex> Use regex for name search -not Insert before other options to negate -maxdepth <levels> Descend only to levels deep -samefile <file> Find all hard links of a file -xdev Don't descend directories on other filesystems -inum <inum> Find files with the inode number -type <f|d|b|...> Find files of type -delete Delete found files -exec <cmd> {} \; Find files and execute command for every found file. '{}' is replaced with filename -exec <cmd> {} + Find files and execute command with all filenames in place of '{}' -atime +/-n Find files that were last accessed less or more than n days. -print0 | xargs -0 <cmd> Sends found files to a command as parameters. Uses 'NUL' character as separator, necessary for filenames with spaces
locate <regex>	Similar as 'find' but using index
	-i Ignore case --regex Interprets all patterns as extended regex -0 | xargs -0 <cmd> Sends found files to a command as parameters.
updatedb (sudo)	Update locate index
md5sum	Prints md5 sum hash of a file
read	Read single line from standard input
	-n 1 Print after reading one character -s Do not echo input coming from terminal
shred	Securely remove files
file	Determine file's type
tree	Ls in a tree-like (hierarchical) format
install	Copy files and set attributes
gpg	Decrypt file with password
	-c Encrypt
mktemp	Create a temporary file or directory in '/tmp' and returns it's name.
rename	s/<from>/<to> <files> Renames multiple files using 'sed' syntax
rsync	A fast, versatile, remote (and local) file-copying tool
	-Hbaz -e ssh '<src_dir> <user>@<host>:<dest_dir>' - Backs up the 'src-dir': '-H' preserves hard links, '-b' renames preexisting destination files (back up), '-a' preserve everything except hard links and '-z' compresses. cmp Compares two files, similar to diff but also for binaries
stat	Displays files status
	-c%X Time of last modification of the file
readlink	-f Follow link recursively and print files path
xdg-open	Open file with default application for the file type
dialog	Display dialog box from shell script
watch	Execute command periodically

Archives

dtrx	<archive> Universal archive extractor
tar	xvzf <file>.tar.gz (.tgz) Decompress and detar xvjf <file>.tar.bz2 Decompress and detar -cf <archive>.tar <files> Compress
unzip	\*.zip Backslash is necessary so that bash doesn't expand the '*' -d <dir> Extract into directory (create if doesn't exist)
zip	-r <archive> <dir> Compress whole directory recursively. -g <archive> <files> Add files to existing archive (grow).
unrar	e Extract files from rar archive
zcat	Cats gziped file

Terminal Multiplexers

screen	Switch between multiple virtual terminals (useful in ssh). Prefix for a command is 'Ctrl a'.
	c New terminal, n Next, p Previous, a Go to beginning of line, | New region vertically, S New region horizontally, tab Move to next region, Q Close all but selected region, X Kill the current region, esc Enter copy/scrollback mode -> space: start/stop marking, ] Paste, k Kill window, t Show time and avg CPU load
tmux	Terminal multiplexer, better screen. Prefix for a command is 'Ctrl b'. Most commands are the same as in 'screen'.
	ls Shows running sessions attach [-t <no>] Attach to running session d Detach from currently attached session pgup Enter in copy mode and pageup, [ Copy mode, ] Paste, " Split horizontally, % Split vertically

Bash#

"$x"	ALWAYS PUT DOUBLE QUOTES AROUND VARIABLE!!!!!!!!!!!!!!! All variables in bash are global!!!!!!!
"$*"	Combines all the arguments into single word, separating them with first character of IFS variable. If IFS is not set, space is used. If IFS is null, no separator is used!!!!!!!!! No args provided will result in one empty string being passed on!!!
"$@"	Use this instead!!!!! Will retain arguments as-is, so no args provided will result in no args being passed on. This is in most cases what you want to use for passing on arguments. Google: "$@" is right almost everytime, and $* is wrong almost everytime.
"$#"	Number of arguments
"$1"	First argument
"$0"	Name of the script
$'\n'	String literal with escape sequences (there is a backslash before n) If you want IFS to be a new line (useful with for loop) you need to: 'IFS=$'\n'' - The dollar forces substitution!!!!! Also if you want 'while read line; do...' to preserve leading spaces and tabs, you need to set IFS=""
$?	Exit code of last command (0 - Success)
Ctrl-Z, kill %%	Kill looping bash script

test <expr>	Same as '[ <expr> ]'. Returns zero exit status if true.
	-n Is string non empty -z Is string empty -a And -o Or = Strings are equal -nt File newer than -ot Older then -d Directory exists -e File exists -f Is a regular file -h Its a symbolic link -r Has read permission -w Has write permission -x Has execute permission
[[ <expr> ]]	Same as '[', but without word splitting and filename expansion. And with additional operators: '&&', '||', '<', '>' (lexicographic less, more), and also regular expression matching.
=~	Regex comparison operator: '[[ "$HOST" =~ ^user.* ]]'
let <expr>	Executes expression: let a="$b"+2

$(command)	Same as 'command'
eval <variable>	Execute string as command
$RANDOM	0 - 32767
input='cat'	Getting standard input
-	In place of a file name means standard in or out
set -o vi	Set line editing to vi mode
pushd .	Put current dir on stack
popd	Pop dir from stack
cd -	go to last dir
source <script>	Run script: for example source /etc/profile (same as . <cmd>)
#!/bin/bash	Good practice to insert at beginning of a bash script
export	PATH="$PATH:<dir>" Adds new directory to path environment variable.
read	-p <message> Prompt for user input
var=${1:-"<default>"}	Setting variable with default value if $1 is empty
getopts	Parse parameters/arguments, builtin
getopt	GNU version is even better then getopts, not a builtin
while read line; do <commands>; done < <file>	Read from file line by line
	-r Do not treat backslashes as escape characters
complete -F <completion_function> <cmd>	Set completion function for command
complete -p <cmd>	Print the completion function for command
compgen -c <pattern>	Print all completions for pattern
help <builtin>	Display information about builtin command
wait	Wait for all background processes to end

Safety

set	-e Exit if any command fails -u Exit if referencing undefined variable -o pipefail If any command in a pipeline fails, its return code is used as the return code of the whole pipeline
IFS=$'\n\t'	Remove space from the default Internal Field Separator

History

sudo !!	Run the last command as root
␣<cmd>	Execute a command without saving it in the history
!<cmd>	Run last command that starts with cmd

Redirections

<cmd> 2> /dev/null	Redirect error output to 'null'
<cmd> &> /dev/null	Redirect both standard and error output to 'null'
<cmd> >&2	Write to stderr
<cmd> 2>&1 | less	Add stderr to stdout and print it with less (useful for gcc)

Arrays And Lines

Reads line by line from variable. To preserve spaces use 'IFS='.

while IFS= read -r line; do
    echo "... $line ..."
done <<< "$list" — 

${a[1]}	Value of the second element of the array
for c in ${a[@]}	Iterate over array
${varname:offset:length}	Get substring: 's="aeiou"; ${s:3:1} -> o'
${#var}	Length of a var
${#name[subscript]}	Length of the element
${#name[@]}	Length of the array

Aliases And Functions

alias	Print all aliases
	<name> Print alias <name>='cmd' Set alias
command <cmd>	Executes original command, bypassing any aliases or shell functions that may be defined for command
\<cmd>	Temporarily disable alias (call original)
type <cmd>	Will tell you what is command aliased to or if it is a builtin, function or a command -P just check commands
declare -F	Print function names
declare -f	Print functions

Text#

Print

head	-n-<num_of_lines> Print all lines but the last n -c <num_of_chars> Print first c characters
tail	-n+<line_num> Start at line number -f Do not stop printing (follow)
cat	-n Number all lines >> file Simplest text editor (great for pasting)
less	&<patt> Display only lines with pattern -N Show line numbers -~ Do not show '~' after 'EOF' +G Tells less to start at the end of the file +F Follow the input (to scroll up first press ctrl+c) -F Or --quit-if-one-screen v Opens editor defined in '$VISUAL' or '$EDITOR' :n Examine the next file <, > Go to home, end
wc	Count lines, words and characters

Edit

sudo -e <file>	Edit file as sudo
tr <from> <to>	Translate characters
	-d Delete characters
cut <file>	Removes columns from each line of files
	-d ':' -f 1,7 /etc/passwd Only show the username and the shell
sort	Sorts lines
	-u Uniq, removes duplicates -t Set delimiter for fields (default is space) -k Select by which field to sort
uniq	Removes adjacent duplicates
	-d Intersection -u Difference
column	Columnate text
	-t Create a table
shuf	Shuffle input lines
tac	Concatenate and print files in reverse (reverse 'cat')
join	Join lines of two files on a common field
colrm	[from [to]] Removes columns
seq <number>	Output numbers from 1 to number
ispell, aspell	Interactive spell checker
basename <path>	Strips directory from path
	-s .<suffix> Also strip suffix -a Process multiple filenames
dirname <path>	Strip last component from path
fmt	Produce roughly uniform line lengths
fold	Wrap each input line to fit in specified width
paste	Glue two documents side by side
sed	's///g' Substitute every occurrence in line, not just the first one 's///I' Ignore case -r Extended syntax, for '+', '?', ... Also you shouldn't escape the parenthesis -r 's###e' Execute match as a command -i <file> Will make changes directly to the file (in place) -u Unbuffered mode (processes input immediately) -n l Print escape sequence (keycode) of a pressed key
expand	Convert tabs to spaces
	-t <number> Set number of spaces (default is 8) -i Do not convert tabs after non blanks

Diff

diff	-u <files> Unified format --brief -r Compare two directory trees
colordiff	Version of diff with colors
sdiff	Two files side by side
comm	Compare two sorted files line by line
patch	Apply a diff file to original
	patch < patch.diff Apply patch diff -u <old_file> <new_file> > patch.diff Create patch

Search

grep <patt> <file>	-v Inverse -n Line numbers -w Whole word -A<num> Print also num lines after -B<num> Print also num lines before -r Recursive -o Print only matching part -P Perl notation with additional operators such as: '\\t', '+' and '?' (non-greedy!!!!). -i Ignore case -I Do not process binary files -l Just print files with matches -L Just print files without matches -e <patt> Necessary to put before pattern if it starts with '-'!!!!!!! or if you want multiple patterns. | wc -l Count occurrences --line-buffered Processes input line by line instead of in bigger chunks
look	Display lines beginning with a given string
strings	Print all text parts of binary file

Convert

todos, fromdos	Convert line endings form/to windows format (package tofrodos)
enscript	Converts text files to postscript, rtf, HTML
gs	Ghostscript: postscript and PDF language interpreter and previewer
pdftohtml	Pdf to html
pdftotext	Pdf to text
libreoffice	New Openoffice
figlet	Display large characters made up of ordinary screen characters (Ascii art)
toilet	Similar (Ascii art)
cproto	Generates C function prototypes (declarations)

Editors

nano	Simple text editor.
	/etc/nanorc Config file. /usr/share/nano/<lang>.nanorc Syntax highlight files. Alt + / or ? Go to last line.
fte	Cool text editor with CUA (IBM)-shortcuts
diakonos	Simple terminal text editor with ctrl-c for copy
pyroom	Distraction free writing (gui)

Network#

whois	Info about domain
host <ip/hostname>	DNS lookup utility
nslookup	Same interactively
dig	Same, lot of options
hostname	Prints/sets computer name, to set it permanently edit '/etc/hostname' and '/etc/hosts'
netstat	Displays contents of /proc/net files, status of ports...
	-r Show routing table -i Show interfaces
arp	Manipulate the system ARP cache (IP -> mac)
route	Tool used to display or modify the routing table
	add default gw <ip> Change the default gateway should DNS not be configured correctly on your machine, you need to edit '/etc/resolv.conf' to make things work
ifconfig eth0	down/up (sudo) Turn network interface on/off <ip> netmask <mask> up Set ip and mask
ifup eth0	Will bring eth0 up if it is currently down.
ip	link show List network interfaces link set dev eth0 up Bring interface eth0 up or down addr show List addresses of interfaces route add default via <ip> Set default gateway
traceroute, traceroute6, traceroute6.iputils	Traces route
tracepath, tracepath6	Similar (iputils package)
mtr	Combines the functionality of the traceroute and ping
findsmb	List info about machines that respond to SMB name queries - Windows based machines sharing their hard disks
/etc/services	List of internet services with their port numbers
NetworkManager	Network management daemon, configuration file is in /etc/NetworkManager/NetworkManager.conf
nm-tool	Prints info
nm-online	Is network connected
nmcli	Command-line tool for controlling NetworkManager
nc	(netcat) It can open TCP connections, send UDP packets, listen on arbitrary TCP and UDP ports, do port scanning...
ncat	Concatenate and redirect sockets
ethtool eth0	Show status of eth0
	-S Statistics -s Change settings (speed, duplex,...)
ss -tupl	List internet services on a system
	-tuo List active connections to/from system

Wireless

iwconfig	Sets the wireless configuration options basic to most wireless devices
iwlist wlan0	<option> Displays current status information of a device, more detailed then iwconfig scan (sudo) List wireless networks in range
iwspy	Sets the list of IP addresses in a wireless network and checks the quality of their connections
iwpriv	Accesses configuration options specific to a particular device
rfkill	list Show wireless adapters (wifi and bluetooth) block/unblock <dev_num> Block/unblock wireless device
iw dev wlan0	link Show link status of wlan0 set biterates <standard> Manually set interface speed scan (sudo) List wireless networks in range
wavemon	Monitor wireless connection link quality

Internet#

mutt	Mail client
sftp	Secure ftp
sshd	(openssh-server) ssh server deamon, on Windows service is named 'CYGWIN sshd'

/etc/init.d/ssh restart (sudo)	Restart sshd (ssh deamon)
/usr/local/etc/init.d/openssh start (sudo)	Start openssh deamon
ssh-keygen -t rsa -C <email>	Generate rsa key pair, keys are stored in ~/.ssh

ssh	SSH client
	<user>@<address> "mpg321 -" < <file>.mp3 Stream audio over ssh enter ~. Kill unresponsive session
scp	Securely copy files over network. Example: 'scp <local_file> <user>@<host>:~<remote_file>'
wget	Download files from WWW
	-O Specify output file -c Continue downloading unfinished file. Can also use wildcards, but use single quotes around url. -r -l1 --no-parent -A.gif Recursively to the depth of one ignoring references to the parent directory and all gifs.
curl	Similar
	-qO - Writes to standard output + quiet -i Urls specified by standard input
transmissioncli	Torrent terminal client
	-d Download limit (kB/s) -u Upload limit
youtube-dl	Download from YouTube
noip2	Dynamic dns update client
rdesktop	Remote Desktop Protocol client
tin, nn	Usenet client
nrss	Rss feed reader

Browsers

lynx	Terminal web browser
	-cmd_log=<file> Write keystrokes to script -cmd_script=<file> Read keystrokes from script -syslog-urls Log requested URLs with syslog. -dumb Prints txt to stdout -crawl Same, turns numbers off -source Prints html to stdout -l Add the current link to your bookmark file a Save the address of a document or link to a bookmark file, by default ~/lynx_bookmarks.html o Options (you can select vim mode) ctrl+n Scroll down two lines ctrl+p Scroll up two lines ctrl+p Previous line crrl+n Next line
elinks	Another web browser (has menus)

Hacking

nmap	-sP 192.168.1.1-3 Network scanning 192.168.1.3 -p100-139 Port scanning -O 192.168.1.3 (sudo) Scanning os
tcpdump (sudo)	Sniffer (show network traffic)
	-l Buffered output (for piping to less, etc.)
ettercap	Multipurpose sniffer/interceptor/logger for switched LAN (can detect man in the middle, denial of service, DNS spoofing)
driftnet	Picks out and displays images from network traffic
kismet	Wireless 802.11b monitoring tool
aircrack-ng	Wireless WEP/WPA cracking utilities
Cain & Abel	Password recovery tool for Microsoft Operating Systems
dnsniff	Warious hacking tools:
	arpspoof For man in the middle attack dsniff Password sniffer for several protocols, ...
ip link set eth0	promisc on Set network interface to promiscuous mode multicast off Set multicast off

System#

meta, system info	In cinnamon
uname -a	Print system info, kernel version
cat /etc/issue	Show name and version of distribution

init	Upstart init daemon job configuration
telinit	Change system runlevel
dmesg	Print the contents of your bootup (startup) messages displayed by the kernel. This is often useful when debugging problems
getconf -a	Print all system configuration variables
nohup <cmd>	Run a command immune to hangups, runs even after the shell is closed (writes output to nohup.out)
	&>/dev/null & Run a command immune to hangups in background, do not save output
wmctrl	X Window Manager
awesome	Tiled window manager
	-k Check configuration script for errors

busybox <cmd>	Combines tiny versions of many common UNIX utilities into a single small executable. (1.5 Mb)
mono	.NET support

Users

users	Prints logged in users
who	Logged in users, more data
w	Logged in users, also what are they running
vipw	Edit password file
vigr	Edit groups file
umask	the umask is a value set by the shell. It controls the default permissions of any file created
usermod <user>	Modify user account information
	-l <new_name> <old_name> -c "<new_real_name>" <user> -d /my/new/home <user> Change location of the users home -m -d /my/new/home Also move the files
useradd <user>	Add user
adduser <user>	More high level (use 'adduser <user> sudo' after to add user to sudo group)
	--system Create system user (can not log in) <group> Add user to group (only takes effect after login!!!)
groups <user>	What groups user belongs to
userdel -r <user>	Remove user and his home dir
deluser	-remove-all-files <user> More high level, removes also files outside home, cron jobs, itd
passwd <user>	Change password

File Systems

mkfs	Build a Linux filesystem
mke2fs	Create a ext filesystem
mkswap	Set up a swap area
parted	Partition manipulation program
	-l (sudo) List partitions
fdisk	Manipulate disk partition table
	-l (sudo) List partitions
disks	Nice GUI partition tool
mount	List all mounted devices (to get list of devices use 'fdisk -l')
	<device> <path> For example mount /dev/hdc2 to /mymedia
lsattr	List file attributes
chattr	Change file attributes
rkhunter -c	Checks if it can find any rootkits under the system
ntfsundelete	Undelete files on NTFS partition

Logging

last	When various users have logged in or out. This includes information on when the computer was rebooted.
lastlog	Displays a list of users and what day/time they logged into the system. To get all failed logins run: 'cat /var/log/auth.log | grep "failed password" -i'.
rsyslogd	manages all the logs on your system closelog, openlog, syslog, vsyslog -> library calls that send messages to the system logger
logger	Makes entries in the system log
zeitgeist	Activity logger

Load

tload	'graphic' representation of system load
top	Show processes by resource consumption
	<, > Change resource
htop	Better top
free -tm	Displays memory statistics
	-s <seconds> Continuously display
vmstat	Performance of system components / virtual memory statistics
sar	System activity information
iostat	Disk usage
time <cmd>	Time a execution of a command
perf	Profiler

Tracing

auditd	System call auditing (package)
ausearch	Querys the audit logs
autrace	Traces a specific process
auditctl	Controls the behavior of the auditd server
strace <cmd>	Trace system calls and signals. All printed system calls can be looked up by 'man'!
	-s Maximum string size we want printed (default is too short, 2000 is OK) -f Also follow children -p <pid> Attach to process -o <file> Write output to file -c Count/aggregate -T Time the execution of each call
ltrace	List library calls made by command
lsof	List open files with file descriptors
	-p <pid> Open files by process <path> Open files in path
lsmod	Show which kernel modules (drivers) are loaded
modinfo <module>	Get more information about kernel module

Hardware

lshw (sudo)	List all hardware
lspci [-tv]	Show pci info
lsusb [-tv]	Show usb info
lscpu	Print CPU information
dmidecode -q	Display bios/dmi information like ram size/type, max ram, computer model name, cpu information.
smartctl	-A /dev/sda Show disk usage info
hdparm	-tT /dev/sda Do a read speed test
badblocks	-s /dev/sda Check for bad blocks
fstrim -v /	Discard unused blocks, useful for ssd-s
sensors	(lm-sensors) hardware monitoring tool, temperature, fan speed
pwmconfig	(fancontrol) set fan speed

Terminal

tty	Print the file name of the terminal connected to standard input
stty	Change and print terminal line settings
openvt	run a program on a next available tty
script	Makes a typescript of everything printed on your terminal. Ctrl-d to stop recording.
setterm	Set terminal attributes
	-cursor off/on Set cursor on/off
gpm	Enable mouse for tty

Keys/Characters/Fonts

In X

xmodmap	Remap keys
setxkbmap -layout us	Set us keyboard layout
xev	Get keycodes of pressed keys
xset	User preference utility for X
	-r Turn key autorepeat off r Turn key autorepeat on

X Not Necessary

loadkeys <country_code>	Load key mapping
showkey	Get keycodes of pressed keys
setfont <font>	Set console font
	/usr/share/consolefonts/Uni2-VGA16.psf.gz For example /etc/default/console-setup contains the default settings
jfbterm	Enable unicode characters in terminal
echo -en "\e]PC7373C9"	Change blue color in tty (first numeral after P means slot, and others shade)

Processes#

ps --forest	View hierarchical view of processes
	v Virtual memory --sort <field> Sort by field
pstree	Similar
pgrep <pattern>	Prints PIDs of processes containing pattern
	-l Also print process name
pkill <pattern>	Kills every process that contains pattern in name
kill	<pid> Sends TERM signal to process -kill <pid> Sends KILL signal meaning force quit, data will be lost
killall	Uses name instead of pid
skill	Sends signals to command/user/tty or report process status
	-stop <user> Stop all of the users processes -cont <user> Continue all users processes
nice	Sets the priority for a process (from max of -20 to min of 20)
	-20 <cmd> Execute command with maximum priority
renice	Changes the priority of an existing process
	+20 <pid> Change processes priority to lowest level
snice	Works very similarly to skill
	-10 -u root Increase the priority of all root's processes
pmap	Report memory map of a process (mapped file)

Jobs

Ctrl z	Put job into background
jobs	Prints currently running job
bg <job_id>	Put job in background
fg <job_id>	Bring job to the foreground
%n	Job number n
%s	Job whose command line starts with s
%%	Current job
%-	Previous job

Scheduled Commands

at	Executes command at a particular time at 21:30 / at now + time / at -f shell_script now + 1 hour echo "ls -l" | at midnight
atq	List jobs currently in 'at' queue
atrm	Remove a job from the 'at' queue
crontab -e	Schedule commands for repeating execution
cron	Daemon that executes scheduled commands
	sudo service cron status Print status of cron sudo service cron [stop|start|restart] Stop, start, or restart cron deamon sudo vim /etc/default/cron Set logging lever cat /var/log/cron Print log
anacron	Like cron but it catches up with tasks next time the computer gets turned on

Services

service	Allows you to start, stop or restart a service (it runs a script in /etc/init.d folder)
	-f sshd Restart the ssh server httpd status Get status of apache --status-all Print status of all services You can also execute the shell script directly from /etc/init.d folder like: /etc/init.d/httpd stop.

System Runlevels

runlevel	Output previous and current runlevel
	0 Shuts down the system 1 Administrative single-user mode 2 Same as 3 but without networking / multiuser with X server 3 Text mode state (ctrl+alt+F1) / User defined 4 User defined 5 X-window mode (ctrl+alt+F7) / User defined 6 Reboots S Single user mode

Multimedia#

Audio

alsamixer	Set audio level (curses)
amixer	Set audio levels (command line)
rmmod pcspkr (sudo)	Disable pc-speaker, beep

cmus	Music player (can be controlled from outside)
mplayer	Movie/music player
mpg321	Plays mp3
ogg123	Plays ogg
aplay	Plays audio
play	Plays audio
arecord <file>	Command line audio recorder and player
	-f <format> Set file format (cd) -d <seconds> Set duration -f cd -d <seconds> -t raw | lame -x -r Out.mp3 — Capture audio that is playing and convert it to mp3
id3v2 -l	Lists all files tags
sound-juicer	Cd ripper
xfburn	Cd burner
traverso	Simple daw

Bitmap

display	Displays an image
montage	Creates a montage from images
	<input_file/s> -set label '%t' <output_file/s> Labels images
convert <old> <new>	Converts file format (imagemagick)
import	Captures screen-shots from the X server
mogrify	Edit image
gocr	Command line text recognition tool
ocrad	Command line text recognition tool
ppmforge	Creates picture of random planet or clouds
gnuplot	Interactive plotter: plot [-10:10] sin(x)
	-p Leave plots open after exit plot <file>.dat Plot data from dat file
fbi	Display images inside tty

Video

ffmpeg -i <file_in> <file_out>	Video and audio format converter. Has been replaced by avconv
avconv -i <file_in> <file_out>	Video and audio format converter (libav-tools)

openshot	Gui movie editor
openmovieeditor	Gui movie editor
aview, asciiview	ASCII art image viewer and video player

Awesome Debian Files

Bash

~/.bashrc	Executed at every shell startup, user specific
/etc/bash.bashrc	Executed at every shell startup, all users
~/.profile, .bash_profile, .bash_login	First file found executed at login, user specific
/etc/profile	Executed at login, all users (put PATHS here)
/etc/rc.local	Last startup script executed, runs command as su

Home

~/.Xmodmap

Keyboard map

Bins

/bin	Key programs like ls, cat, bash, ...
/sbin	Key programs for system management like ifconfig, mkfs, fdisk, ...
/usr/bin	Distribution managed programs
/usr/sbin	Distribution managed system programs
/usr/local/bin	User programs not managed by the distribution package
/usr/local/sbin	User system management programs, not managed by the distribution package

General Config

"Edit To Configure" or "Editable Text Configuration".

/etc/mailcap	Default programs for extensions
/etc/passwd	Users
/etc/groups	Groups
/etc/default	Boot script parameters that the end user or administrator is likely to change.
	/console-setup Set console (tty) character set, font size, ...
/etc/fstab	Filesystem table. To mount drive at startup, create dir in '/media' and append line like this : '/dev/sda1 /media/data ntfs user,fmask=0111,dmask=0000 0 2' (Check 'man fstab' for details).
/etc/alternatives	Links to default application versions (here you can change the default Java JDK)
/etc/issue	Name and version of distribution
/etc/fstab	Automatic mounts are handled by configuring the file
/etc/sudoers	Lists of users and the commands they can run with sudo (needs to be edited with visudo command)
/etc/apt	/sources.list List of places where to look for packages

Services

/etc/init/, ~/.init/	Init Upstart init daemon job configuration
/etc/init.d	Folder with service scripts, that get executed at start and end
	/halt Runs at the end
/etc/rc<level>.d	Startup scripts for different runlevels - Links to scripts in /etc/init.d - S85httpd -> S means startup, K is for stop. (To disable service just change S for K)
/etc/rc.local	Last initialization file executed - Put your commands here

/etc/init/ssh.conf	Sshd config
/etc/ssh/sshd_config	Sshd config
/etc/crontab	System-wide crontab
/etc/cron.hourly, /etc/cron.daily, ...	Links to scripts that will execute periodically. Scripts within a cron directory are run alphabetically.
/etc/rsyslog.conf | rsyslog.d/50-default.conf	Log conf (need to restart rsyslogd after edit)
/etc/syslog.conf	Configuration information for syslogd

Network

/etc/resolv.conf	Dns information
/etc/sysconfig	/networking/devices/ifcfg-eth0 Use ifcfg to configure a particular interface
/etc/services	List of internet services with their port numbers
/etc/NetworkManager	/NetworkManager.conf Configuration file

Proc

Various information about the system.

/proc/cpuinfo	Information about the CPU
/proc/modules	information about which kernel-modules are loaded on your system
/proc/net	Network related
	/route Routing table /netstat Displays contents of /proc/net files
/proc/iomem	Neat memory map
/proc/partitions	Partitions info
/proc/acpi	/battery/BAT1/info Battery info /ac_adapter/ACAD/state Adapter info /wakeup List of devices that can wake up your machine via acpi sudo sh -c "echo USB1 > /proc/acpi/wakeup" Enable device USB1 to wakeup computer from sleep/suspend
/proc/net/wireless	Wireless connection info

Usr

"Unix System Resources"

/usr/lib	/jvm Java JREs and JDKs
/usr/share	/man Man pages /bash-completion Bash completion functions

Sbin

The "system-administrator's bin file". Hosts programs that would be in /bin if they didn't have "root-only" access permissions.

Var

"Variable"

/var/log	System logs in here
	/auth.log Logins /syslog Most of the rest of the logs
/var/spool	Contains data which is awaiting some kind of later processing

Boot

Kernels.

/boot/grub/menu.lst	Grub configuration file
/etc/default/grub	Grub configuration file

Git

Git Mantra

git init
git add <file> OR git add .
git status
git commit -am "<commit_message>"

Clone From Github

git clone git@github.com:/<user>/<project>

Download repo (later you keep refreshing with 'git pull origin master') -> You need SSH key. If you don't want, use https://github.com/<user>/<repo> for address.

Generate Ssh Key

1.	Check for existing keys: cd ~/.ssh; ls -al
2.	Generate new key: ssh-keygen -t rsa -C "your_email@example.com"
3.	Add your key to the ssh-agent: ssh-add ~/.ssh/id_rsa
4.	Add your key to GitHub: copy contents of ~/.ssh/id_rsa.pub and paste them into key field at 'Account settings' > 'SSH Keys' > 'Add SSH key'.

Add To Github

# Create remote repository on website.
git remote add origin git@github.com:/<user>/<project>.git
git pull origin master
git push origin master
# Sometimes also: git push --set-upstream origin master

Remote

git remote	update Get info about state of remote show origin Print address of the origin set-url origin <origin> 'git@github.com:<user>/<repo>.git' - Change the url of origin, ssh key needed; 'https://www.github.com/<user>/<repo>.git' - Same, but withouth key.
git status -uno	Check if everything up-to-date
git fetch; git checkout <branch>	Checkout remote branch

Tags

git push --tags	Push tags
git fetch --tags	Pulling tags (automatically if on the same branch and there is a new commit?)

Undo

git reset

--hard HEAD~1 Delete last commit and all of its changes HEAD~1 Delete last commit but keep your changes

Also Useful

git checkout HEAD^ <file>	Retrieve deleted file
git rm --cached <file>	Untrack file without deleting it
git tag -a 0.9.1 -m "Version 0.9.1 release"	Tag latest commit
git tag	List local tags
chown -R <user>:<group> * (sudo)	In .git/objects
git format-patch -1 <sha>	Generate patch file
git rev-parse HEAD	Get sha of head
git revert
git describe	Print version and hash of HEAD
git log --name-only --author=<name>	Print changed files by commit
git log <file>	Print files history
git ls-files	List files
git show <revision>:<file>	Take a peek at the older revision of the file
git diff <commit> <commit>	Compare two commits
git stash	If you want to switch branches, but you don't want to commit your changes yet, you can 'stash' them
git stash apply	Apply the changes you stashed
git stash list	List all the stashes
git stash show -p stash@{0}	Show the diff of most recent stash
git update-index --chmod=+x <file>	Change files permissions
git config -l	Print repos configuration settings
git config core.filemode false	Ignores executable bit of the files

Checkout

git log > ../gitLog	First save log to file
git checkout <hash>	Then checkout previous versions
git checkout head	Return to head

Github Md Format


Insert image

Bisect

git bisect start
git bisect bad	Tell git that current version is bad
git bisect good v25.0.2	Tell git the last good version you know about. Now git will checkout a version in between, so you can check it and tell:
git bisect bad/good	This will continue until the commit that introduced the bug is found
git bisect reset	Exit bisect mode

Tools

gitk	Repo explorer
gitg	A bit nicer version
tig	Text based repo explorer
gitstats	Generates stats for git repo, outputs HTML

Virtual Box

git config core.filemode false	Ignores the filemode changes made by the host system
git config --global --unset https.proxy	If problem pulling

Vim

+<linenum>	Open file at line number
alt+<normal mode key>	Escape, key !!!!!!!!!!!!!!!!!
ctrl+[	Escape
.	Execute last command again
;	Repeat the last character-wise search
\c	Case insensitive search
?	Search backward
V	Linewise visual mode
~	Switch case
>	Tab selection right
>>	Tab line right
P	Paste before cursor
x	Delete character
gF	Open file under cursor
K	Look up word under cursor in man pages
ctrl+v	Select visual box (block select)
:e	Reload file
:sav	Save file as and keep new file open (save as)

Help

ctrl+]	Follow link
ctrl+o	Go back
:q	Exit help

Movement

e	End of word
E	End of WORD
W	Start of WORD
ge	End of previous word
), (	Sentence
{, }	Paragraph
]], [[	Section
:<num>	Goto line number
ctrl+o	Go to previous location
ctrl+i	Go to next location
%	Jump to matching bracket

Lines

0	Start of line
^,_	First non-blank of line
+,-	First non-blank of next/previous line
Enter	First non-blank of next line

Screen Lines

g0, g$	Start/end of screen line
gm	Middle of screen line
gk, gj	Up/down one screen line

Page Up/Down

H,M,L	Go to top/middle/bottom of screen
ctrl F,B	Page up/down
ctrl D,U	Half page up/down
ctrl E,Y	One more line at bottom/top
z Enter, z., z-	Reposition line with cursor at top/middle/bottom

Search

*,#	Search forward/backward for exact word under cursor
g*,g#	Same, but even when word is embedded
%	Find match of current brace, quote,...
fx,Fx	Move cursor forward/backward to x on current line
tx,Tx	Same, but to one char before x
;/,	Repeat/reverse last
:%s/old/new/gc	Replace, like sed, c means with conformations

Marks

'"	Move to position of last edit of file
`.	Move to last change in file
`0	Position where you last exited vim

Insert Mode Commands

ctrl+h	Backspace
ctrl+u	Delete line
ctrl+w	Delete previous word

Macros

q<x>	Record actions (macro) into x
q	Stop recording macro
@<x>	Execute x (macro)

Registers

"ayy	Copy line into register a
"ap	Paste register a
:reg	Access all registers

Set Command

:set <x>	Set x
:set no<x>, <x>!	Unset x
:set <x>=value	Assign x
:set <x>-=value	Remove value form <x>
:set all	Print all values
:set <x>?	Print x

Set Command Operands

autoident, ai	Autoident (noai)
backup, bk	Back file up before overwrite (nobackup)
ignorecase, ic	Ignore case in search (noic)
number, nu	Display line numbers (nonu)
relativenumber, rnu	Display relative numbers (nornu)
shiftwidth, sw	Number of spaces added when indenting (8)
tabstop, ts	Tab width (8)
wrap	Wrap lines (wrap)
wrapscan, ws	Search wraps around file (ws)
mouse=a	Mouse mode (use shift when selecting to copy to clipboard)
linebreak	Do not break words

:set iskeyword-=.

Remove dot from words part (two words if separated with dot)

Edit Commands

[n] operation [m] motion

If both n and m are specified then n x m

c, d, y	Change, delete, yank
C, D, Y	Till the end of line
cc, dd, yy	Current line
cf<x>, df<x>, yf<x>	Forward up to x
c), d), y)	Sentence

~	Change case of character
g~w	Switch case of a word
gu, gU	To lower/upper case

[p	Paste but match current indentation
r	Replace character
S	Substitute entire line
x,X	Delete character/delete back
.	Repeat last change
ctrl+a, ctrl+x	Increment/decrement number under cursor

Automatic Linebrake (Wrap)

gq	Formats (wraps) selected text
gqq	Format current line
:set tw=72	Set text width

Advanced

tw=72 fo=cq wm=0	No automatic wrapping, rewrapping will wrap to 72
tw	Controls the wrap width you would like to use
fo	Controls whether or not automatic text wrapping is enabled, depending whether or not the t flag is set
wm	Controls when to wrap based on terminal size

Colorscheme

:colorscheme	darkblue, torte Nice, darker slate, default Less contrast
:highlight Normal ctermbg=grey	Set light background

Spellcheck

:set spell spelllang=en_us	Turn spellcheck on
:set nospell	Turn off
:setlocal spell spelllang=en_us	Set dictionary
z=	Show suggestions for misspelled word
]s	Go to next misspelled word
[s	Go to previous misspelled word

Tabs

:tabe <file>	Open new tab
gt, gT	Go to next/previous tab
ctrl+pgup/pgdn	Switch tab
vim -p	Open one tab page per file
ZZ	Save and close tab (same as :wq)

Splits

:vsp	Split vertically
ctrl-w, direction	Move to split

Autocomplete

ctrl+n

Show autocomplete suggestions

Hexdump

:%!xxd	Convert to hex
:%!xxd -r	Convert back

Vundle

:PluginInstall

Install plugins

Reformat Code

=	Fix indentation

Misc

Piratebay

torrents.thepiratebay.sx/7532474/Cabin.torrent

Download torrent file

Java

javac -cp <path>:<path>...	Tell Java where libraries are located
java -Xmx6g myprogram	Reserve 6 giga for process
	-jar <jar> Execute jar -cp .:<path>:<path>... Tell java where libraries are located, you also need to pass the location of class among paths, hence .:
export _JAVA_OPTIONS=-Xmx1000m	Set heap space globally
appletviewer <page>.html	Run Java applet
jps -lvm	List java processes
jmap -histo:live <pid>	Memory map
jvisualvm	Profiler
jar cvfe "bla.jar" <main_class> *.class	Create executable jar
jar xf <jar>	Extract files from jar
jar tf <jar>	Print contents of a jar

Install Oracle Jdk

sudo apt-get remove openjdk*
sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
sudo apt-get install oracle-java7-installer

Install Oracle Jdk On Debian

echo "deb http://ppa.launchpad.net/webupd8team/java/ubuntu precise main" | sudo tee /etc/apt/sources.list.d/webupd8team-java.list
echo "deb-src http://ppa.launchpad.net/webupd8team/java/ubuntu precise main" | sudo tee -a /etc/apt/sources.list.d/webupd8team-java.list
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys EEA14886
sudo apt-get update
sudo apt-get install oracle-java7-installer
sudo apt-get install oracle-java7-set-default

Firefox

about:config

Layout.css.devPixelsPerPx default zoom (-1.0)

Xrandr

xrandr

--output VGA1 --primary Changes primary screen --output VGA1 --auto --pos 0x0 '--output LVDS1 --auto --right-of VGA1' - To change their relative positions -q List devices --auto Reset --output LVDS1 --off Turn off laptop screen --output [VGA|HDMI] --mode 1600x1200 24" 16x12 on

Mount Iso

sudo mkdir /media/x
sudo mount -o loop <path_to_iso> /media/x

Eclipse

ctrl+1	Quick fix
alt+shift+s	Source submenu
ctrl+F7, esc	Close pop-up console window
ctrl+7, ctrl+/	Toggle comment
F3	Goto definition
objectaid	UML plugin

Wine

winecfg	Drives tab to set drive
wine explorer /desktop=abalaba,1024x768 app.exe	Run wine app in virtual desktop
reason on wine: down alt down	Open menu
regedit	Registry editor

Cygwin

[cygwin] ssh-host-cofig
[command prompt] net start sshd
[any] ssh <windows_username - CASE MATTERS!>@<host>	Run sshd (use windows password)

Golang

go

build Compile packages and dependencies clean Remove object files env Print Go environment information fix Run go tool fix on packages fmt Run gofmt on package sources get Download and install packages and dependencies (first you need to set GOPATH to dir where packages will get downloaded) install Compile and install packages and dependencies list List packages run Compile and run Go program test Test packages tool Run specified go tool version Print Go version vet Run go tool vet on packages

syntax highlight	'https://github.com/jnwhiteh/vim-golang'
for gedit	'sudo cp /usr/share/gtksourceview-3.0/language-specs/go.lang /usr/share/gtksourceview-2.0/language-specs/'
simple ncurses	Go get github.com/nsf/termbox-go

Repackaging A Linux Install Iso

# Mount ISO
mkdir -p /mnt/linux
mount -o loop /tmp/linux-install.iso /mnt/linux

# Copy contents to a working directory
cd /mnt/
tar -cvf — Linux | (cd /var/tmp && tar -xf — )

# Make your changes and repackage (on Debian use genisoimage). -c passes the name of the file that will be created
cd /var/tmp/linux
mkisofs -o ../your-new.iso -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -J -R -V Your Disk Name Here .

Gdb

gdb <cmd>	Start gdb
run <arguments>	Start debugging
run < <file>	Run with piped input
up	Follow trace
print <variable>	Print variable

Coredump

ulimit -c unlimited	Set core file limit to unlimited
gdb <cmd> core	Debug core file with gdb

Chrome

F6, ctrl+l, alt+d

Go to address bar