DEV Community

Asim Dahal
Asim Dahal

Posted on

Using grep and history command to find previous commands in Linux

#linux #productivity #webdev #beginners

You input command in your linux terminal which is very long and hard to remember. It is needed to input the command again to the terminal. You find it hard to search for the command that is needed. You keep pressing up arrow again and again until the required command is found. Time is wasted during this process.

This is where history command comes in. Go to your linux terminal and type the command history. You will find the list of commands you previously used like this.
Use of history command

In the above image you can see all the previous commands you have used along with their respective numbers. Now let's assume you have to use the command git clone https://github.com/asimdahall/wethanks/ which is number 56. Now you can execute the command by typing ```

asims-MacBook-Pro:~ !56

which will execute the command on number 56.
Now let'say we have to search the previous command that we have used. For that, we can combine grep with the history command. Let's take a case here. I have to search for the command 
```xcrun

 simctl shutdown all 

``` which I have used before but I don't remember the full command and only remember `xcrun`. So for searching the command, we can combine the `history` and `grep` command like this:
Enter fullscreen mode Exit fullscreen mode

asims-MacBook-Pro:~ asim$ history|grep xcrun

after that you will get the following output
Enter fullscreen mode Exit fullscreen mode

422 xcrun simctl shutdown all
452 xcrun simctl shutdown all
454 xcrun simctl shutdown all
502 history|grep xcrun


you get all the commands where `xcrun` command is used with their respective numbers. Now you can execute the command like this:
Enter fullscreen mode Exit fullscreen mode

asims-MacBook-Pro:~ asim$ !422

which will then execute the needed command.

 I am sorry for the bad grammar. Feedbacks and suggestions are kindly welcome. Thank you. 


You can follow me on [Twitter](https://twitter.com/asimdahall)
Enter fullscreen mode Exit fullscreen mode

Top comments (4)

Collapse
 
ferricoxide profile image
Thomas H Jones II •

If you know the command you're trying to repeat, then !<starting-string> is great. Similarly, if you know the command you're trying to repeat, but you need to modify it, !<starting-string>:s/<SEARCH>/<REPLACE> or even !<starting-string>:gs/<SEARCH>/<REPLACE> are freaking awesome.

Note: This type of advanced command-history usage works in BASH and CSH-derived shells. Dunno about other shell-families.

Collapse
 
darkes profile image
Victor Darkes •

Big fan of using history, I'd be lost if I didn't have it. My personal way of accessing it on Macs is by using Ctrl + R and that let's you do pretty much the same thing as the grep method and you don't have to do the second line to execute the expression. Give it a try!

Collapse
 
programmist profile image
Tony Childs •

If your .bash_history file is large (as mine is), piping the output of the history command to grep can be very slow. For example, my current history file is over 100k lines, and it takes 10+ seconds (on my machine) for the command to complete.

A faster method is to simply grep the file directly, which takes under 1 second:

grep xcrun ~/.bash_history
Enter fullscreen mode Exit fullscreen mode

Or, even better, set up a function to do this:

# hg - History grepping function
hg () {
    grep "$1" ~/.bash_history
}
Enter fullscreen mode Exit fullscreen mode

then:

hg xcrun
Enter fullscreen mode Exit fullscreen mode

Or if you use Ripgrep (As I do):

hg () {
    rg "$1" ~/.bash_history
}
Enter fullscreen mode Exit fullscreen mode
Collapse
 
ayoubbougue profile image
ayoub bougue •

super useful,thanks for sharing

Read next

lithephp profile image

How Lithe Makes Web Application Development in PHP Faster with Less Code

Lithe -

digitaldrreamer profile image

Running a Function When an #await Block resolves in Svelte(Kit)

Abdullah Bashir -

dev007777 profile image

Python beats Javascript, Next.js Leap & the AI Coding Wars

TheDev -

mcsee profile image

Code Smell 279 - Loop Premature Optimization

Maxi Contieri -