July 29, 2023

Copy a command from the shell history to a file

To copy a command from the shell history to a file run:

$ echo [event designator]:q  > file.txt

An event designator is a reference to a command line entry in the history of the shell¹. For example if you want to run the last command again, run $ !-1 or the synonym $ !!.

The q that comes after the event designator is a modifier which tells bash to enclose the substitution (e.g. !!) in single quotes (’) to prevent further expansion by the shell.². Modifiers are always preceded by a colon, i.e. :.

The > redirection operator tells the shell to redirect the output of a command - here echo - to a file which will be created if it does not exist.

So, with all of this in mind, we can for example run:

$ echo !!:q  > file.txt

which will copy the last command in the shell history to a file. Or

$ echo !-2:q > file.txt

which will copy the penultimate command in the shell history to a file.

If you can’t count how far back in the shell history the command you want to copy to a file is, run:

$ history | tail

then find our the number (n) of the command you want to copy to a file, then run:

$ echo !n:q > file.txt

See also:

• Copy a command from the shell history to the clipboard.

To learn more about event designators run $ man history then type /Event Designators.

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1. From the man page.↩︎

2. in the words of a GNU/Linux contributor.↩︎

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I do self-funded research and I'm writing a book.

> What's the book about?

About technologies and agency.

Meaning, technologies can foster agency. No doubt. But I am also asking:

Can usage of technologies give us a sense of empowerment while in fact undermining our abilities?

I posted a summary of the prologue on the homepage: https://yctct.com/

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