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"

The `${1:-}` in this case evaluates to an empty string if `$1` is not set, but `shift` fails when there is no argument to remove.

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