10 Useful Tips for Using the Exclamation Mark (!) in Linux

The exclamation mark (!) in Linux Bash can serve as a logical negation operator or a powerful shortcut to work with command history. With it, you can re-run, modify, or reference previously executed commands efficiently.

Below are 10 useful techniques for using ! in Linux, tested in the bash shell (though some may not work in other shells).

1. Run a Command from History by Number

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$ history
$ !1551

Runs the command listed at number 1551 in history.

2. Run Previous Commands by Relative Position

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$ !-6
$ !-8
$ !-10

Runs the 6th, 8th, or 10th-to-last command.

3. Reuse the Last Argument from the Previous Command

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$ ls /home/$USER/Binary/firefox
$ ls -l !$

!$ inserts the last argument of the previous command.

4. Work with Multiple Arguments

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$ cp /home/avi/Desktop/1.txt /home/avi/Downloads
$ echo "1st: !^"
$ echo "2nd: !cp:2"

• !^ = first argument
• !cp:2 = 2nd argument from last cp
• !* = all arguments

5. Run a Previous Command by Keyword

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$ !ls -l

Runs the last command that started with ls -l.

6. The Magic of !!

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$ apt-get update
$ sudo !!

Repeats the last command (!! expands to it).

7. Use ! for Logical NOT with File Patterns

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$ rm !(2.txt)
$ rm !(*.pdf)

Deletes everything except specified files.

8. Check if a Directory Exists

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$ [ ! -d /home/rumenz ] && printf 'No dir\n' || printf 'Exists\n'

9. Exit if Directory Does Not Exist

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$ [ ! -d /home/rumenz ] && exit

10. Create a Directory if It Does Not Exist

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$ [ ! -d /home/rumenz ] && mkdir /home/rumenz

Quick Reference Cheatsheet

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Final Thoughts

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The exclamation mark ! is far more than just a negation operator. In Bash, it provides shortcuts for reusing history, arguments, and even controlling file operations with patterns. Mastering these 10 tips can save you time, prevent errors, and boost your efficiency on the Linux command line.