Just another blog post describing another rookie mistake (the most fun kind of blog post). You get a gold star if you can predict the mistake that I will make.

Today I wanted to rerun a command from my bash history.

I know that I can run history to get a list of my past commands, and I can then run history | grep <search_term> to pull back some nice clues to what I want to do (given that I have usually forgotten the exact command).

However, I was guessing that the people that wrote history must have been clever enough to include functionality to directly run commands from the history command.

My normal debugging process was “helpful” here.

Peters-MacBook-Pro:~ peterreeves$ history --help
-bash: history: --: invalid option
history: usage: history [-c] [-d offset] [n] or history -awrn [filename] or history -ps arg [arg...]

And man history gave me the big BSD blurb..

BUILTIN(1)                BSD General Commands Manual               BUILTIN(1)

NAME
...

I noticed the -c flag from the history: usage: output and I decided to have a guess at history -c 2133. “This must run the command #2133 from the output of history! I bet the -c stands for “count”, like ping -c!” My computer hung for about 10 seconds. I panicked and googled.

Turns out the -c stands for clear.

I lost my >2200 command bash history. It slightly felt like the first time that you run rm -rf from the wrong directory, usually to wipe out your last hour’s work.

I should have guessed, given by the “BSD General Commands Manual” man page, that running a command from one’s history would be built into bash. Turns out, the correct way to run command 2133 from your history is !2133. It is so obvious now.