A small quality of life improvement to the rails runner command that gives a more helpful error message when given a path as input to a file that doesn’t exist:
$ rails runner foo.rb Please specify a valid ruby command or the path of a script to run. Run 'rails runner -h' for help. undefined local variable or method `foo' for main:Object
$ rails runner foo.rb The file foo.rb could not be found, please check and try again. Run 'rails runner -h' for help.