For a short-lived script, the `${1:?missing argument}` stuff may be useful, but usually, I want to print some longer usage or help text in the error case.

I usually go with something like this:

  set -eu
  
  function eusage() {
    echo "Usage: $0 <input-file> <output-file>" >&2
    echo "Error: $@" >&2
    exit 1
  }

  infile=${1:-}; shift || eusage "Missing input filename"
  outfile=${1:-}; shift || eusage "Missing output filename"