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Linux Cheat Sheet

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Getting help

View the manual for target command

man command

Get help with a target command (probably the same as above, but not always):

command -h

In case you forget the name of a command, print possible commands relating to any given word:

apropos word

View index of help pages:


Command Line Utilities

Basic File and Directory Operations

Print current working directory:


Show files in current directory:


Show maximum information about all files, including hidden:

ls -a

Recurse into subdirectories and list those as well:

ls -R

List files by modification time, most recent first.

ls -lt

Move/rename a file or directory (be careful that you don't move the source over a destination with the same name):

mv source destination

Delete target forever (be very careful), use -r recursive flag for directories:

rm target

Copy file or directory:

cp source destination

Mount filesytem:

mount /dev/device/name /media/device/name


umount /media/device_name

Forensically clone filesystems and do other low-level operations on files. Be careful with this one. Can be destructive:


Work with disk partitions:


Filesystem creation tool:


System Administration

Execute command as an administrator (can be destructive/insecure. Use only for system administration tasks):

sudo command

Become system administrator:

sudo -s

Quit system administration:


Forgot to type sudo in front of a command and already hit enter? Repeat the last command using sudo:

sudo !!

Installing software from a .tgz (also known as a tarball)

First, unzip the tarball (see section on tar, below) Next, move into unzipped directory

cd software_directory

Always read README first if it is provided, in case there are any modifications to the procedure outlined below:


Automatically check for appropriate configurations and generate a MAKE file in the directory:


Compile software. May require sudo:


Move files into their appropriate locations. May also require sudo:

make install

Clean up files in directory, in case make command fails, or just to remove unnecessary cruft:

make clean

Ubuntu/Debian Software repositories

Check distro repositories for software updates:

sudo apt-get update

Download and install updates (update first):

sudo apt-get upgrade

Search for package in the repositories:

apt-cache search keyword

Get more detail on one specific package:

apt-cache show package_name

Download and install a package:

sudo apt-get install package_name

View the output of a command in a more convenient format:

command | less

Working With Files

Print a file in terminal:

cat file

Find files matching filename:

locate filename

See the version of a program or the location of the program

which appname

Search through filename for matches to phrase:

grep phrase filename

Search through output of a command for phrase:

command | grep phrase

Working With Processes

List all running processes:

ps -e

Standard system monitor showing a more extensive view of all processes and system resources:


Like top, but with a better, cleaner interface:


Stop a process from using all system resources and lagging computer:

renice process_name

Kill misbehaving process (use sparingly, last resort, try 'renice' command first):

pkill process name

Start a process in the background

command &

Start a process in the background and have it keep running after you log off

nohup command &

Compression and Encryption

Make a simple compressed backup of files or directories:

tar -cvzf backup/output.tgz target_files_or_directories

Open a compressed .tgz or .tar.gz file:

tar -xvf target.tgz

Encrypt a file:

gpg -o outputfilename.gpg -c target_file

Decrypt a file:

gpg -o outputfilename -d target.gpg

Zip and encrypt a directory simultaneously:

gpg-zip -o encrypted_filename.tgz.gpg -c -s file_to_be_encrypted

The Bash shell

File Name expansions

Current user's home directory:


Current directory:


Parent directory:


Or even (Two parent directories down):


All files in target directory. (Be very careful.):


Output Redirects

Redirect output of one command into the input of another with a pipe:

command_1 | command_2

Or even:

command_1 | command_2 | command_3

Redirect output to a file:

command > file


file > file

Or even, to redirect in a different direction:

file < file

Append output rather than writing over the target file:

file_or_command >> file

Works like |, but it writes output to both target and terminal:

tee target

Redirect standard output and error to /dev/null, where it is deleted.

command > /dev/null 2>&1

Controlling Execution

Wait until command 1 is finished to execute command 2

command_1 ; command_2

Or even:

command_1 ; command_2 ; command_3

&& acts like ; but only executes command2 if command_1 indicates that it succeeded without error by returning 0.

command_1 && command_2

double pipes || act like && but only executes command_2 if command_1 indicates an error by returning 1.

command_1 || command_2

Bash Wildcards

Zero or more characters:


Matches “phrase” and any number of trailing characters:


Matches any incidences of “phrase” with any trailing or leading chars:


Matches any one char:


Matches any of the characters listed inside brackets:


Matches a range of chars between a-z:



Command Line Utilities, Continued


Configure network interfaces:


Configure wireless network interfaces:


Connect to a remote server.

ssh username@ip_address

Forward X from target to current machine (Get a remote desktop. Somewhat obscure, but very useful):

ssh -X username@ip_address

Copy files/directory over the network from one machine to another recursively:

scp -r source_filename:username@ip_address target_filename:target_username@target_ip_address

Copy only changes between files or directories (super efficient way to sync directories, works either locally or with remote servers using username@ip_address:optionalport, just like ssh):

rsync source target

Check to see if target is online and responding

ping ip_address

View network route to target:

traceroute6 ip_address

Network Monitor


View firewall rules

iptables -L

Scan this machine(localhost) to check for open ports:

nmap localhost


download a file over http:


complete a partially downloaded file:

wget -c

start download in background:

wget -b wget -c

download a file from ftp server:

wget --ftp-user=USER --ftp-password=PASS


Listen for input from network on recieving_port, dump it to a file (insecure, but handy):

netcat -l recieving/port > file/copied

Pipe the output of a command to a target ip and port over the network:

command | netcat -w number_of_seconds_before_timeout target_ip target_port

Use tar to compress and output a file as a stream, pipe it to a target ip and port over the network:

sudo tar -czf - filename | netcat -w number_of_seconds_before_timeout target_ip target_port

Users and Groups

Change owner of a file or directory:

chown user_name:group_name directory_name

Change privileges over file or directory (see man page for details.)


Create a new user:


Change user privileges (be very careful with this one):


Delete user


Print groups:


Create a new group:


Change group privileges:


Delete group:


Temporarily become a different user:

su username

Print usernames of logged in users:


Write one line to another user from your terminal:


Interactive talk program to talk to other users from terminal (must be installed from repositories.):


Working With Files, Continued

View what processes are using what files:


View the differences between two files:

diff file_1 file_2

Output the top numberoflines of file:

head -n number_of_lines file

Like head, but it outputs the last -n lines:

tail -n number_of_lines file

Checksum a file:

md5sum file

Checksum every file in a directory (install this one from repositories.):

md5deep directory

Checksum a file (better algorithm with no hash collisions):


Same operation as md5deep, but using sha1:


Call command every few numberofseconds, and highlight difference in output:

watch -d -n number_of_seconds command

Execute command, print how long it took:

time command

View files in directory from largest to smallest:

du -a directory | sort -n -r | less

remove spaces from filenames in current directory:

rename -n 's/[\s]/''/g' *

change capitals to lowercase in filenames in current directory:

rename 'y/A-Z/a-z/' *

Environment and Hardware

print motherboard information


Print full date and time:


Print the hostname of this machine:


Print information about current linux distro:

lsb_release -a

Or even:

more /etc/issue

Print linux kernel version:

uname -a

Print information about kernel modules:


Configure kernel modules (never do this ;p ):


View Installed packages:

dpkg --get-selections

Print environment variables:


List hardware connected via PCI ports:


List hardware connected via USB ports:


Print hardware info stored in BIOS:

sudo dmidecode

Dump captured data off of wireless card:


Dump info about keyboard drivers:


Ubuntu System Administration, Advanced (Continued)

Add a Personal Package Archive from Ubuntu Launchpad:


Install a .deb file from command line:

sudo dpkg -i package.deb


Update pip (Python package manager):

pip install -U pip

search pip repos for a library:

pip search library_name

create a virtual python environment to allow install of many different versions of the same Python modules:

virtualenv dirname --no-site-packages

connect to a virtual python environment

source dirname/bin/activate

disconnect from a virtual python environment:


install package into virtual python environment from outside:

pip install packagename==version_number -E dirname

export python virtual environment into a shareable format:

pip freeze -E dirname > requirements.txt

import python virtual environment from a requirements.txt file:

pip install -E dirname -r requirements.txt


All commands must be performed in the same directory as .git folder

Start a new git project:

git init
git config "user_name"
git config "email"

Make a copy of a git (target can be specified either locally or remotely, via any number of protocols):

git clone target

Commit changes to a git:

git commit -m "message"

Get info on current repository:

git status

Show change log for current repository:

git log

Update git directory from another repository:

git pull [target]

Push branch to other repository:

git push [target]

Create a new branch:

git branch [branchname]

Switch to target branch:

git checkout [branchname]

Delete a branch:

git branch -d [branchname]

Merge two branches:

git merge [branchname] [branchname]

Show all branches of a project:

git branch


clone a virtual machine (this works, it's been tested):

vboxmanage clonehd virtual/machine/name.vdi --format VDI ~/target/virtual/machine_name.vdi

mount a shared virtual folder: you need to make sure you have the right kernel modules. You can do this with modprobe, but this package works instead in a ubuntu-specific way.

sudo apt-get install virtualbox-ose-guest-utils
sudo mount -t vboxsf name/of/shared/folder/specified/in/Virtualbox path/of/mountpoint


Get help:


Show databases:

show databases;

Choose a database to use:

use database/name/here;

Show database schema:

show tables;

Delete database:

DROP DATABASE databasename;

New database:

CREATE DATABASE databasename;

Create a new user:

CREATE USER username@localhost IDENTIFIED BY 'password';

Show users:

select * from mysql.user;

Delete a user:

delete from mysql.user WHERE User='user_name';

Give user access to all tables (make them root). the “%” means that they can sign in remotely, from any machine, not just localhost.:

grant all privileges on /./ to someusr@"%" identified by 'password';

give certain privileges to a user on a certain database:

grant select,insert,update,delete,create,drop on somedb.* to someusr@"%" identified by 'password';

Tell mysql to use new user priv policies:

flush privileges;

change user password:

use mysql;
update user set password=password('newpassword') where User='user_name';

mysql command line args: export text file with commands to rebuild all mysql tables:

mysqldump databasename > dumpfilename.txt

restore from a dump:

mysql -u username -p < dumpfilename.txt

dump entire database:

mysqldump -u username -p --opt databasename > dumpfile.sql

restore from entire database dump: <file bash>mysql -u username -p –database=databasename < dumpfile.sql

 linuxfind.1620856717.txt.gz · Last modified: 2021/05/12 21:58 by bpienig
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