Template script with basic help, error handling and utilities

template.bash

#!/bin/bash
set -o errexit -o nounset -o pipefail
function -h {
cat <<USAGE
 USAGE: template.bash

  Implement your script with this template.

USAGE
}; function --help { -h ;}                 # A nice way to handle -h and --help
export LC_ALL=en_US.UTF-8                    # A locale that works consistently

function main {
  : Write functions for each script task. Change `main` to call one of them.
}


##################################################################### Utilities

function msg { out "$*" >&2 ;}
function err { local x=$? ; msg "$*" ; return $(( $x == 0 ? 1 : $x )) ;}
function out { printf '%s\n' "$*" ;}

# Handles "no-match" exit code specified by POSIX for filtering tools.
function maybe { "$@" || return $(( $? == 1 ? 0 : $? )) ;}


######################### Delegates to subcommands or runs main, as appropriate

if declare -f -- "${1:-}" >/dev/null
then "$@"
else main "$@"
fi