Living the Pipe Dream
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How to find previously used terminal commands in Linux and macOS

Unix shells remember which commands you have issued through them. Here are a few ways to make use of that command history.

We have to go back, Kate!
Jack Shephard tells us we have to go back into our shell history

We have to go back, Kate!

One line at a time

Almost everyone already knows this one, but I’m mentioning it anyway for the sake of completeness: you can easily look up previously entered commands by pressing the Up button (⬆︎) until you’ve found what you’re looking for.

If it’s been a while since you last executed that command, it may take a lot of key presses before you get there though…

All the history

The history command lists almost all commands that have been issued by the user that’s currently logged in. This is mainly handy in situations where you want to see an overview of commands.

By sending the output of the history command to grep using a pipe operator (|) we can filter the history so that it only shows commands that contain specific words. For example, to show all previously used commands that include the string “git config” you would run history | grep 'git config':

$ history | grep 'git config'
   75  git config user.email "hurleyquotes@example.com"
  125  git config user.email "hurleyquotes@example.com"
  237  git config user.email "hurleyquotes@example.com"
  239  git config user.email "hurleyquotes@example.com"
  242  git config user.email "hurleyquotes@example.com"
  292  git config user.email "hurleyquotes@example.com"
  299  git config user.email "hurleyquotes@example.com"
  396  git config user.email "hurleyquotes@example.com"
  399  git config user.email "hurleyquotes@example.com"
 1426  git config user.email "hurleyquotes@example.com"
 3454  history | grep git config

Don’t forget to add quotes to your search string if it contains spaces; otherwise grep will try to treat each subsequent keyword as a file or directory name:

$ history | grep git config user
grep: config: No such file or directory
grep: user: No such file or directory

GOTO history

Most people who use the history | grep method manually copy and paste the command that they want to execute again, but there’s actually no need for this. You may have noticed that each line of history’s output is prefixed by something that resembles a line number.

Entering !, followed by the number of the command that you were looking for, and pressing Enter will write the contents of that line to the terminal:

$ !1426
$ git config user.email "hurleyquotes@example.com"

sudo make me a sandwich

There’s another shortcut, !!, which you can use to quickly reissue the last command. This is especially useful when you forgot to prepend sudo to your command:

$ touch /etc/sandwich
touch: /etc/sandwich: Permission denied

Instead of manually retrieving and modifying the last command, simply use !!, which serves as a placeholder for the contents of the original command:

$ sudo !!
Password:
$

The final method to look up previously issued commands is the method that I use most often: interactive search.

Press Ctrl + R to enable interactive search mode. You can now look up commands by entering a search string, e.g. git push (no need to add quotes).

If you’ve found the command you want, press Enter to execute it. Otherwise, keep typing to improve your query, press Ctrl + R to view the next result, or press Ctrl + C to exit interactive search mode.

Interactive search mode can be a huge time saver, so make sure you use it often!