k

k is a script to repeatedly run a command on file changes.

k stands for keep it running.

Install

curl https://raw.githubusercontent.com/seanlerner/k/master/k > /usr/local/bin/k && chmod +x /usr/local/bin/k

Prerequisites

k requires entr, ag and an increased maxfiles limit.

Instructions are provided on how to install and set these up when attempting to use k for the first time.

How to use

k <your command>

Control-C once will stop and restart the current command.

Control-C twice quickly will stop running k completely.

What k does

k does a few things out of the box. It:

• repeatedly runs a command each time a file changes within the current directory or a subdirectory.
• clears the screen and prints the name of the command at the top before executing it.
• continues to run even if a file is deleted or added to the current directory / subdirectory.

Where k is useful

k is useful when you want to run a command over and over again.

Test failures

For example, if a test is failing using Ruby and minitest, the message will look like so:

E

Error:
YourTest#test_your_test:
RuntimeError:
    test/test_your_test:6:in `block in <class:YourTest>'

bin/rails test test/test_your_test.rb:5

You could then issue the command:

k bin/rails test test/test_your_test.rb:5

and continue to work on your code until the test passes.

Simple program output

If you're learning a new programming language or doing a 'code challenge' type of test, you could use:

k ruby my_program.rb

to display the results of your program every time you save it.

Linting

The shell script linter ShellCheck was used to lint k.

In this case, the command was:

k shellcheck k

How it works

k uses entr and ag under the hood.

It's possible to achieve a similar effect by using ag -l | entr -cd <your command>. However, this script does a few extra things to make the experience a little more pleasant (see What k does).