Using the up arrow to run previous commands in bash? If so you’re doing it wrong! Get to know you’re bash history and how you can use it to your advantage. When you press the up arrow you are cycling through you bash history, which you can see at anytime with the history command.

history | tail
 1993 tmux
 1994 finch
 1995 cd Projects/blog/
 1996 git pull origin master
 1997 rake -T
 1998 rake new_posts["Bash Tips and Tricks"]
 1999 vim
 2000 history | tail

First, say you want to rerun the very last command you just issued, instead of pressing the up arrow you can use the ‘double bang’ operator, which is the last command you ran.

!!
history | tail
 1993 tmux
 1994 finch
 1995 cd Projects/blog/
 1996 git pull origin master
 1997 rake -T
 1998 rake new_posts["Bash Tips and Tricks"]
 1999 vim
 2000 history | tail

Not to bad, but there is more power to !! than first meets the eye. Think of it as just the text of last command that is replaced as bash picks it up. Because of this you can tack extra items to the front or end of it.

!! | grep rake
history | tail | grep rake
 1997 rake -T
 1998 rake new_posts["Bash Tips and Tricks"]
 2001 history | tail | rake

You can also run a specific command from history with !n

!1997
rake -T
rake clean # ...

My favorite so far is !?. It looks back from the history stack until it finds a command that a command that matches it.

!?pull
git pull origin master
From github.com:benfalk/blog
 * branch            master       -> FETCH_HEAD
Already up-to-date.

One last trick, say you goofed a command like so

ps aux | grep tmx
bfalk    18334  0.0  0.0  15944   920 pts/26   S+   22:16   0:00 grep --color=auto tmx

You can clean it up with :s

!!:s/tmx/tmux
ps aux | grep tmux
bfalk     2416  0.0  0.0  15800  1160 pts/2    S+   20:48   0:00 tmux
bfalk     2418  0.2  0.0  25472  2848 ?        Ss   20:48   0:12 tmux
bfalk    18627  0.0  0.0  15944   920 pts/26   S+   22:18   0:00 grep --color=auto tmux

The :s/find/replace will search through the last command and replace the first instance of “find” and replace it with “replace”. If you want to replace all occurrences then use :gs/find/replace. This may seem like a silly thing but imagine; however, imagine you have hand crafted some long command… With this you can rectify it quite quickly!

It is hard to clear that muscle memory of using the up arrow to sift through my bash history, but, hopefully with these commands you’ll be able to start saving time on the command line as you get used to making fewer keystrokes ; )