bash-history-expansion

History Expansion

ok so bash remembers everything you type (check ~/.bash_history) and you can pull stuff back really fast.

the ones I actually use

!! — reruns the last command. everyone knows the sudo trick:

apt update
# nope, permission denied
sudo !!

!$ — last argument from whatever you just ran. I use this ALL the time:

mkdir /tmp/whatever
cd !$

saves so much retyping. there’s also !^ for the first arg and !* for all of them but honestly I mostly just use !$.

finding old stuff

!ssh runs your last command that started with ssh. kinda dangerous though — you might not remember exactly what that command was. safer version: slap :p on the end to preview it:

!ssh:p
# shows what it WOULD run, without actually running it

Ctrl+R is honestly better for searching history though, see bash-keyboard-shortcuts.

the typo fixer

this one’s underrated:

cat /etc/ngnix/nginx.conf
^ngnix^nginx

boom, fixed. only does the first occurrence though.

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see also: bash-keyboard-shortcuts, bash-brace-expansion

gnu manual on this stuff if you want the deep dive