The Art of Using the Command Line

20 curated super bash One-liners commands for your day to day

I love the Linux command line, so I have written several articles where I show tricks and utilities that bring us real utility.

On this occasion, I compile 20 command one-liners that I find especially useful. I hope you like them!

1. Show bios information

With the following command, we can see the Bios information of our computer.

$ sudo dmidecode -t bios

2. Encode and Decode a string in base64

We pass a text using the pipeline operator to the base64 command to encode it and add the “- - decode” flag to decode it to the original value. It’s as simple as that.

$ echo password1 | base64
$ echo xxx | base64 --decode

3. Share a folder quickly using a web server

Using python, we can easily share a folder in a URL.

$ cd $mydir && python3 -m http.server 8888

4. A simple way to Monitor memory every 2 seconds:

“watch -n X” repeats a command every X seconds and highlights the differences.

$ watch -n 2-d '/bin/free -m'

5. Execute in one step a pull request in all git directories

A quick way to update all our git repositories is to run the following command:

$ for i in */.git; do cd $(dirname $i); git pull; cd ..; done

6. Convert a CSV file to Json file

You need to have python installed.

CSV file:

$ cat test.csv | python3 -c 'import csv, json, sys; print(json.dumps([dict(r) for r in csv.DictReader(sys.stdin)]))'

Json:

7. Display the Linux distribution information

The following command will display all available information about our current distribution, the package management, and the base details:

$ echo /etc/*_ver* /etc/*-rel*; cat /etc/*_ver* /etc/*-rel*

8. Show a notification when a shell command is completed

If we add “;notify-send done” to the end of a command, we will receive a notification when the command completes.

$ ls -l ;notify-send done

9. Execute command without asking for confirmation

If we want to execute a Linux command without being asked for confirmation at each step, we can use “yes” as follows:

$ yes | sudo apt install XXX

10. Monitoring CPU speed

The default is every 2 seconds.

$ watch grep \"cpu MHz\" /proc/cpuinfo

11. Find broken symbolic links

If we want to find all the broken symbolic links on our system, we can run the following command:

$ find . -type l ! -exec test -e {} \; -print

12. Equivalent to the ENTER key on our terminal

Very useful if, for some reason, the “ENTER” key does not work.

CTRL + m or CRL + j

13. Find the process that is using a specific port

Simple and practical, not much more needs to be said.

$ lsof -P | grep ':8080'

14. Backup a drive into a file on a remote host via ssh

We do not need to use any tool to create a backup of our disk.

$ dd if=/dev/sda | ssh user@server 'dd of=backup_sda.img'

15. One-liner countdown in terminal

We do not need either any third-party application to launch a countdown from the command line and be notified when it reaches zero.

$ for i in `seq 10 -1 1` ; do echo -ne "\r$i " ; sleep 1 ; done ;notify-send ZERO!

16. List the most used commands

With the following command, we can see which have been the most frequently executed commands during the different shell sessions.

$ history |  awk '{a[$2]++}END{for(i in a){print a[i] " " i}}' |  sort -rn |  head

17. Count files in the current directory, including subdirectories

$ find . -type f | wc -l

18. Remove executable bit

The following command recursively removes the executable bit from all files in the current directory.

$ chmod -R -x+X *

19. Simulate the execution of some commands with echo

For example, in this case, we see which files with the .csv extension will be deleted.

$ echo rm *.csv

20. Show all current string values in the ram

A practical way to see the strings we have stored in the RAM.

I hope you found it valuable and entertaining to read. Do not hesitate to try the commands :)

If you liked this post, I think you will like these other posts that talk about the Linux command line:

Any suggestion is always welcome.