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Stefan Judis
Stefan Judis

Posted on • Originally published at stefanjudis.com on

TIL: A preceding space prevents dangerous commands from going into history

Assim Hussain shared on Twitter that he executed a dangerous command by mistake. The command was still accessible in his shell history, and he pressed the UP arrow one time too much.

I have been in that situation, and you may have been, also. 🙈

I like about Twitter that sometimes people reply with useful tips to avoid future mistakes. So did Philippe Martin. He shared that commands executed with a preceding space will not go it into the session history. That sounds great!

# command goes into the history
$ delete everything

# command does not go into the history
$  delete everything
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I tried it right away, but it didn't work. I'm a Zsh user, and it turns out that you have to enable it via a config in your .zshrc.

setopt histignorespace
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In bash, it should work right away (not tested).

There is one thing to mention though. After the execution of a command, every command will be accessible by pressing the UP arrow (this is a feature). Only when you execute another command preceding space command will be inaccessible.

This little trick prevents your future self from executing a dangerous command when pressing the UP arrow one time too much. 🎉

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Andrew (he/him)