Shell script snippets

getopt_template.sh

#!/bin/bash

# nounset: undefined variable outputs error message, and forces an exit
set -u
# errexit: abort script at first error
set -e
# print command to stdout before executing it:
set -x

getopt --test > /dev/null
if [[ $? -ne 4 ]]; then
  echo "I’m sorry, getopt() will fail in this environment."
  exit 1
fi

OPTIONS=o:v
LONGOPTIONS=output:,verbose

# -temporarily store output to be able to check for errors
# -e.g. use “--options” parameter by name to activate quoting/enhanced mode
# -pass arguments only via   -- "$@"   to separate them correctly
PARSED=$(getopt --options=$OPTIONS --longoptions=$LONGOPTIONS --name "$0" -- "$@")
if [[ $? -ne 0 ]]; then
  # e.g. $? == 1
  #  then getopt has complained about wrong arguments to stdout
  exit 2
fi
# read getopt’s output this way to handle the quoting right:
eval set -- "$PARSED"
while true; do
  case "$1" in
    -v|--verbose)
      verbose=y
      shift
      ;;
    -o|--output)
      outFile="$2"
      shift 2
      ;;
    --)
      # split until we see --
      shift
      break
      ;;
    *)
      echo "Programming error"
      exit 3
      ;;
  esac
done

# handle non-option arguments
if [[ $# -ne 1 ]]; then
  echo "$0: A single input file is required."
  exit 4
fi

echo "verbose: $verbose, force: $f, debug: $d, in: $1, out: $outFile"