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Process arguments and options in shell script
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#!/bin/bash | |
usage() { | |
cat << EOS >&2 | |
sample.sh | |
USAGE: | |
bash arg_opt_sample.sh [options] <arg1> [arg2] | |
ARGS: | |
arg1 Required argument. | |
arg2 Optional argument. The default argument is 'arg'. | |
OPTIONS: | |
-a, --option-a Option that has no argument. | |
-b, --option-b <arg> Option that has required argument. | |
-c, --option-c [arg] Option that has optional argument. | |
The default argument is 'ccc'. | |
-h, --help Show this help message. | |
EOS | |
} | |
invalid() { | |
usage 1>&2 | |
echo "$@" 1>&2 | |
exit 1 | |
} | |
ARGS=() | |
while (( $# > 0 )) | |
do | |
case $1 in | |
-h | --help) | |
usage | |
exit 0 | |
;; | |
-a | --option-a) | |
if [[ -n "$OPT_A" ]]; then | |
invalid "Duplicated 'option-a'." | |
exit 1 | |
fi | |
OPT_A=1 | |
;; | |
-b | --option-b | --option-b=*) | |
if [[ -n "$OPT_B" ]]; then | |
invalid "Duplicated 'option-b'." | |
exit 1 | |
elif [[ "$1" =~ ^--option-b= ]]; then | |
OPT_B=$(echo $1 | sed -e 's/^--option-b=//') | |
elif [[ -z "$2" ]] || [[ "$2" =~ ^-+ ]]; then | |
invalid "'option-b' requires an argument." | |
exit 1 | |
else | |
OPT_B="$2" | |
shift | |
fi | |
;; | |
-c | --option-c | --option-c=*) | |
if [[ -n "$OPT_C" ]]; then | |
invalid "Duplicated 'option-c'." | |
exit 1 | |
elif [[ "$1" =~ ^--option-c= ]]; then | |
OPT_C=$(echo $1 | sed -e 's/^--option-c=//') | |
elif [[ -z "$2" ]] || [[ "$2" =~ ^-+ ]]; then | |
OPT_C=ccc | |
else | |
OPT_C="$2" | |
shift | |
fi | |
;; | |
-*) | |
invalid "Illegal option -- '$(echo $1 | sed 's/^-*//')'." | |
exit 1 | |
;; | |
*) | |
ARGS=("${ARGS[@]}" "$1") | |
;; | |
esac | |
shift | |
done | |
if [[ "${#ARGS[@]}" -lt 1 ]]; then | |
invalid "Too few arguments." | |
exit 1 | |
elif [[ "${#ARGS[@]}" -gt 2 ]]; then | |
invalid "Too many arguments." | |
exit 1 | |
fi | |
get_nth () { | |
local n=$1 | |
shift | |
eval echo \$${n} | |
} | |
ARG1=$(get_nth 1 "${ARGS[@]}") | |
ARG2=$(get_nth 2 "${ARGS[@]}") | |
if [[ -z "$ARG2" ]]; then | |
ARG2=arg | |
fi | |
echo "ARG1 $ARG1" | |
echo "ARG2 $ARG2" | |
echo "OPT_A $OPT_A" | |
echo "OPT_B $OPT_B" | |
echo "OPT_C $OPT_C" |
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