Nix: Watch That Program

Have you ever been working in the terminal and found yourself repeating the same command many times? Delegate that work to the computer.

watch comes with Linux and can be installed on OSX via homebrew. It executes a program periodically, defaulting to every two seconds. The period can be changed with the -n flag though:

watch -n 2 rspec spec/some/test.rb

We used it today while writing a database backup script. Instead of checking our dump directory every time a cron job executed, we ran watch ls, and watched the script succeed or fail with live updates.

The -d flag instructs watch to highlight the parts of the output that are different from the previous run of the command.

So if I run:

watch -d curl -LIs localhost:3000

I can easily see if the http status of the request changes.

man watch for more information.

Via jwworth/til and jbranchaud/til.