Do you ever find yourself having to re-run a Bash command? I often find this
happening to myself when I neglect to use sudo for a command that requires
root privileges.
$ pacman -Syu
error: you cannot perform this operation unless you are root.
Well, I have good news for you -- you can easily re-issue a command with the
!! designator! Simply type sudo followed by !! and you're good to go.
$ sudo !!
sudo pacman -Syu
[sudo] password for colton:
:: Synchronizing package databases...
--
Commands that are prefixed with a bang, !, are considered Event
Designators, and are references to your command-line history. You can take a
look at your history with the history command.
$ history
1021 touch hello_world.txt
1022 ls
1023 echo "Here we go again!"
1024 find . -name *.py
There are many ways to use ! in your shell. For example, if you wanted to
re-issue a specific command in your history, you could use !n where n is
the number next to the command in your history.
$ !1023
echo "Here we go again!"
Here we go again!
Or... if you wanted to run the command you issued 4-commands ago, you can use
!-4.
$ !-4
ls
hello_world.txt
Or... if you wanted to run the last command that started with the string
find, you can use !find.
$ !find
find . -name *.py
Be sure to check out the Event Designators section of the bash man pages
for more information!
--
As an aside, for even faster command-line history navigation, be sure to check
out the excellent fzf utility by junegunn.
One of the many features of fzf is browsing and re-issuing commands from your
command-line history with a fuzzy-finder!