I periodically update this list with useful bash commands I routinely use. Here, I have used ubuntu based commands for its popularity, although most of them are transfereable to other distros like Manjaro [which I use] by changing package manager from apt to pacman. That being said, I tend to favour installing robby russell’s ohmyzsh to make life easier.

Terminal Commands

Check the number of processors: nproc
Check free RAM : free -h To continuously monitor watch free -h
Checking ubuntu version on the system: lsb_release -a
Checking the processes running as a tree diagram: pstree
Check resource utilization (like task manager in windows): top or htop or ytop(not available on all platforms)
Checking sytem file size: df -ah
Checking file size in directory: du -sh *
Disk partition and disk usage: lsblk
Printing output of a command into a log file: nohup . For eg: nohup lsblk will output the result of lsblk into a log file in the current folder.
- nohup python -u script.py > file.log 2>&1 => Output and error to same file.log
- nohup myprogram > myprogram.out 2> myprogram.err => redirect standard output and standard error to different files
Opening the current folder (GUI) from terminal: nautilus .
Checking linux (kernel) verison: uname -a
Show cpu and motherboard details: lshw -class cpu
To check who are all logged into the system: who or w
pushd and popd to navigate to and back to the directory eg: pushd ~/Desktop
file to print the type of file eg: file foo prints out file format as foo:JPEG image data
search for a file: locate filename.sh prints file location of filename.sh
To constantly update a command every few seconds: watch
tail and head for printing the end and beginning of a file.
Functions which give information about a command: man (manual page), whatis (one line description), info (only available for some commands)
To run a program in the background eg: firefox &
To capture what is being printed during boot: journalctl
Checking internet connection eg: ping 8.8.8.8 or mtr 8.8.8.8
Changing directory/file permissions: sudo chmod 700
Changing ownership: sudo chown
Changing group: sudo chgrp
Listing the directory structure with depth=2 levels : tree -d -L 2
printenv will print out any environment variables you have set.

Running jobs from terminal in background [foreground and pausing]

To run jobs (one or more programs) in foreground and background from terminal. Here, I use firefox as an example to demonstrate the same. on screenshots shown below is scrambled for privacy concerns.

Running programs from terminal

You can always run a job in foreground by typing a command on to the terminal as

firefox

firefox_1

But once the program starts we lose the bash prompt. Another way to start firefox is to run the program in background. This will return bash prompt as shown below.

firefox &

firefox_2

Pause and resume jobs from terminal

Sometimes you need to pause a job that’s running and return to bash prompt and execute some commands and afterwards resume the original job. Press CTRL+Z to pause the original job and return to command prompt as shown below. This will immediately pause firefox and you will note able to use it for browsing the web.

firefox_3