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@druzn3k
Forked from aaronNGi/newscript.sh
Created December 26, 2021 22:46
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Boilerplate for new POSIX shell scripts
#!/bin/sh
prog_name=${0##*/}
version=1.0
version_text="Boilerplate for new scripts v$version"
options="h o: q v V"
help_text="Usage: $prog_name [-o <text>] [-hqvV] [<file>]...
Boilerplate for new scripts
-o <text> Set an option with a parameter
-h Display this help text and exit
-q Quiet
-v Verbose mode
-V Display version information and exit"
main() {
set_defaults
parse_options "$@"
shift $((OPTIND-1))
# If we want to use `getopts` again, this has to be set to 1.
OPTIND=1
# shellcheck disable=2154
{
$option_h && usage
$option_V && version
$option_q && info() { :; }
$option_o && info "option 'o' has parameter '$param_o'"
$option_v && info "verbose mode is on"
}
_i=1
for _file do
info "operand $_i is '$_file'"
_i=$((_i+1))
done
unset _i _file
[ -t 0 ] ||
info "stdin is not a terminal"
}
##########################################################################
# shellcheck disable=2034,2046
set_defaults() {
set -e
trap 'clean_exit' EXIT TERM
trap 'clean_exit HUP' HUP
trap 'clean_exit INT' INT
IFS=' '
set -- $(printf '\n \r \t \033')
nl=$1 cr=$2 tab=$3 esc=$4
IFS=\ $tab
}
# For a given optstring, this function sets the variables
# "option_<optchar>" to true/false and param_<optchar> to its parameter.
parse_options() {
for _opt in $options; do
# The POSIX spec does not say anything about spaces in the
# optstring, so lets get rid of them.
_optstring=$_optstring$_opt
eval "option_${_opt%:}=false"
done
while getopts ":$_optstring" _opt; do
case $_opt in
:) usage "option '$OPTARG' requires a parameter" ;;
\?) usage "unrecognized option '$OPTARG'" ;;
*)
eval "option_$_opt=true"
[ -n "$OPTARG" ] &&
eval "param_$_opt=\$OPTARG"
;;
esac
done
unset _opt _optstring OPTARG
}
info() { printf %s\\n "$*" >&2; }
version() { printf %s\\n "$version_text"; exit; }
error() {
_error=${1:-1}
shift
printf '%s: Error: %s\n' "$prog_name" "$*" >&2
exit "$_error"
}
usage() {
[ $# -ne 0 ] && {
exec >&2
printf '%s: %s\n\n' "$prog_name" "$*"
}
printf %s\\n "$help_text"
exit ${1:+1}
}
clean_exit() {
_exit_status=$?
trap - EXIT
info "exiting"
[ $# -ne 0 ] && {
trap - "$1"
kill -s "$1" -$$
}
exit "$_exit_status"
}
main "$@"
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