Linux Commands Cheat Sheet - LinuxForDevices

Man pages are the authoritative source of information for specific Linux commands. However, seldom do these man pages include practical examples for the commands that might save some time for the user. Here, in this article, I give you the cheat sheet of Linux commands. Let us know in the comments which ones you already knew and if you discovered something new.

Cheat Sheet for Linux commands

For brevity, I have divided this Linux commands cheat sheet into sections. All the commands in a section are often used in conjunction with the other Linux commands in the section. That said, you might also find yourself using a combination of commands in the different sections. That illustrates the power of Linux and the composability of these programs.

Files and directories

`cd /`	Change directory to the root of the filesystem.
`cd target`	Change directory to the `target` directory.
`cd ~`	Change directory to the home directory of the user.

`ls -l`	Long listing, displays file ownership and permissions.
`ls -ltr`	Long listing, but in reverse order of time. Gives the newest files at the bottom.

`cat /etc/system-release`	Displays the contents of the system-release file – which distro and flavor you are running.
`cat longfile.txt \| more`	View a long file page by page.

`cp source_file.txt target_file.txt`	Copies a specific file
`cp -r ~/source_dir ~/target_dir`	Copies all files and sub-directories recursively.
`cp /etc/apt/sources.{d,d.backup}`	Create a backup of `sources.d` file without having to type the full path of the file twice!

mkdir my_directory Make a directory with the name of my_directory.

touch my_file Create a file with the name of my_file.

`mv source_file target_file`	Move a file or a directory.
`mv my_document.{txt,file}`	Rename a file from `my_document.txt` to `my_document.file`

grep -i doctor $(find . -name *.txt -print) Find the string “doctor” in all the .txt files.

Variables and environment

`echo $PATH`	Displays the PATH environment variable
`env`	Displays all ENV variables
`export PATH=$PATH:/anotherdir`	Adds “`anotherdir`” to your PATH, just for your current session.
`source ~/.bashrc`	Reloads .bashrc file. Required if new variables were added or old ones modified in `.bashrc file` and it is required that changes take effect without restarting the shell.

Execution and processes

`./runmyprogram`	Execute a program or shell script in your current working directory (`pwd`).
`./runmyprogram &`	Execute a program or shell script as a background task.

`ps -ef`	Displays information about a selection of the running processes.
`ps -ef \| grep thisprogram`	Find a particular process by name. Here, find `thisprogram`.
`top` or `htop`	Displays a real-time interactive list of running processes.

`kill -9 pid`	Kill the process with PID as `pid`.
`kill -9 -1`	Kill all processes it can kill. Forces a logout.

`whereis executable`	Where all places can the executable be found in the `PATH`?
`which executable`	Which executable among all in `PATH` is executed?

Networking

`ip -4 a`	Shows the IPv4 address for all NICs.
`curl https://ifconfig.me/`	Fetch your external IP Address.
`curl https://www.linuxfordevices.com`	Retrieve the content (HTML) from `https://www.linuxfordevices.com`

wget https://someurl.com/somefile.tar.gz wget is a useful utility for downloading files from any website.

`sudo netstat -pant \| grep LISTEN`	Lists the various in-use TCP ports and the processes using it.
`sudo netstat -pan \| grep 80`	Lists the process listening on port 80.

System Administration

`journalctl -b -p err`	Display all errors since the last boot.
`systemctl status foo.service`	Check the status of `foo.service`
`systemctl start/restart/stop foo.service`	Start/restart/stop `foo.service`
`systemctl enable/disable foo.service`	Enable/disable a service to startup on boot.

`shutdown now`	Shuts down the system immediately.
`shutdown +4`	Shut down the system but after `4` minutes.
`reboot`	Performs a soft reboot.

Package Manangement

`sudo apt install package-name`	Install a package on Debian/Ubuntu based systems.
`sudo dnf install package-name`	Install a package on RedHat based(Fedora, CentOS) systems.

Further …

Although this Linux commands cheat sheet provides you with the most used commands, it’s worthwhile to sit down and read the man pages of individual commands. You might have an obscure problem but going through the man pages, you might stumble upon your required solution. So, do read the man pages in conjunction with this cheatsheet. They’re extremely useful.

I hope you learned some new commands or a new way of doing a particular thing through this cheatsheet. Let us know which commands you already knew and which ones you didn’t know at all in the comments.