Terminal commands every developer should know

The terminal is the developers best friend. Since my change in careers (Marketing -> Software Development) I really fell in love with the terminal. Maybe because I still know the good old MS DOS?

There are some terminal commands that are not that commonly used, but are super helpful and you can get things done faster.

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I am using Ubuntu 18.04 with the bash terminal.

1. tig

Tig is an ncurses-based text-mode interface for git. It functions mainly as a Git repository browser, but can also assist in staging changes for commit at chunk level and act as a pager for output from various Git commands.

tig is a git utility. Yes, tig is git written backwards 🤔 and the commands are nearly the same. The only difference is that tig gives you more.

For example: tig status is like git status.

If you type tig status you get an interactive status of your repository.

you can select the changes and the diff opens.

Since I discovered this feature I am using tig status daily. Use j and k to move up and down, and enter to select. The key h opens the help menu with all the available commands. You can easily add changes to your commit without the need for git add insert-filename-of-your-changes.

2. grep

Grep is a command-line tool that allows you to find a string in a file or stream. It can be used with a regular expression to be more flexible at finding strings, more here or here.

It's very helpful, when you are debugging. Let's say you want to find an error in a 1000+ line log file.

grep error logfilename.log

It will only log the lines where there is the string error found.

3. sudo!! (sudo bang bang)

The !! is called bang-bang operator it repeats your previous command and adds whatever you call it with in front of it.

So sudo!! does the following: instead of typing arrow-up, scrolling to the beginning of the line, adding sudo and hitting enter (imagine scrolling through those long apt-get commands).

4. figlet

Not by default installed, run sudo apt install figlet. With figlet you can draw large sized text banners. Useful, when writing a ReadMe or for welcome messages for services/servers or just for having fun with colleagues.

figlet Hello World

outputs this

 _   _      _ _        __        __         _     _
| | | | ___| | | ___   \ \      / /__  _ __| | __| |
| |_| |/ _ \ | |/ _ \   \ \ /\ / / _ \| '__| |/ _` |
|  _  |  __/ | | (_) |   \ V  V / (_) | |  | | (_| |
|_| |_|\___|_|_|\___/     \_/\_/ \___/|_|  |_|\__,_|

5. history

history returns every command you have typed in. Why is this in this list and how could this be useful?

Well, let me tell you a story about me a person populating a database and chaining commands to make it quick, because you don't populate a database so often. And what happens after 5 hours into the code? Yes, database error, db needs rebuilding and repopulating. And what are the commands? Can you imagine how often I had to hit arrow-up? 😂

With the combination of history and grep I could have narrowed it down.

history | grep db_populate

6. rig

The rig command generates random and possibly fake identities, which is perfect for testing. rig is not pre-installed.

sudo apt install rig

Running rig would create random contacts:

Bettye Dunlap
799 Second St
Denver, CO  80202
(303) xxx-xxxx

7. convert

With convert you can quickly Resize, Convert & Modify Images from the linux terminal.

With Ubuntu 18.04 it already comes installed, if you need to install it, convert is part of the imagemagick-bundle.

sudo apt install imagemagick

You can quickly resize an image. I wanted to resize the title image for this post by 50%.

convert commands.jpg -resize 50% commands--web.jpg

This would create an image with the name commands--web.jpg, which is 50% of the original commands.jpg.

Convert png to jpeg with setting a custom quality.

convert commands.png -quality 50 commands.jpg

You can also modify images like rotate, apply filters and effects and much more.

convert commands.png -quality 50 commands.jpg

To apply a polaroid filter and tilt the image by 25 degrees.

convert commands.jpg -polaroid 25 commands-polaroid.jpg

There are plenty of options available. Check the docs.

The following code really helped me many times for batch rotating images. I was used to create a photoshop action.

for file in *.jpg; do convert $file -rotate 90 rotated-$file; done

What are your favourite terminal commands? I'd love to hear them. Use the comments below or send me a message @mariokandut.

Thanks goes out to out Jackson, How to Geek, Canonical Ltd. and Linux Foundation.