What does !! do?

Question

I can run a command like this:

tim@Hairy:~$ echo Hello
Hello

Then I can run the command !! and it does it again:

tim@Hairy:~$ !!
echo Hello
Hello

I can even run it with another argument to the previous command:

tim@Hairy:~$ !! World
echo Hello World
Hello World

So what is the !! actually doing? I have struggled to search for it because a Google for !! is fairly... pointless.

muru · Answer 1 · 2015-04-23T16:05:53.843

10

A !! is substituted with the last command as is.
A !foo is substituted with the last command that started with foo.
A !^ or a !$ is substituted with the first or last arguments respectively in the previous command.
A !n is replaced with the nth command in history.
A !-n is replaced with the nth-last command in history.
...

edited Apr 23 '15 at 16:05

answered Apr 23 '15 at 16:02

muru

score 4 · Answer 2 · edited Aug 28 '17 at 19:22

4

It's a very short answer:

!! repeats the last command, nothing else.

More "funny" things can you find here.

I have struggled to search for it because a Google for !! is fairly... pointless.

And a better search for that is this:

https://www.google.de/webhp?q=bash+cheat+sheet

edited Aug 28 '17 at 19:22

Stefan Hamcke

answered Apr 23 '15 at 16:00

A.B.

heemayl · Answer 3 · 2015-04-23T17:51:24.260

2

From man bash:

!!   Refer to the previous command.  This is a synonym for '!-1'.

Test:

$ echo "foobar"
foobar

$ !!
echo "foobar"
foobar

$ !-1
echo "foobar"
foobar

edited Apr 23 '15 at 17:51

answered Apr 23 '15 at 16:03

heemayl

3 Answers3