Today I learned

env command allows to find a script’s interpreter when its location is a non-standard one. In scripts it’s recommended to use env in shebang lines to find the executable and run it.

#!/usr/bin/env ruby

puts "Hello, world."

On GNU/Linux if it’s necessary to run a script’s interpreter with options, env has to be used with -S to pass options in shebang lines.

extends attribute in Docker Compose files allows to reuse existing service definitions for other services. That makes it possible to DRY Compose files.

Bundler, a Ruby package manager, provides two options to list gems in the bundle.