[porridgeraisin]

nit: while test and [ are binaries, [[ is a bash keyword.

[__david__]

Another nit, while test and [ are indeed binaries, they are also bash built-ins (for performance, presumably) so bash won’t exec them normally.

[porridgeraisin]

True! And for those curious, you can enable disable this shadowing per command, like so:

  enable test
  enable -n test # disable
  enable -n [

You can also use

  command test -f file.txt

To override builtins once.

[jeroenhd]

Ah, you're right of course. Thank goodness for shellcheck keeping my .sh scripts compatible.