# Simple usage cases for getopts.
#
# OPTIND is either not touched at all (first loop with getopts,
# relying on shell startup init), or getopts state is reset
# before new loop with "unset OPTIND", "OPTIND=1" or "OPTIND=0".
#
# Each option is a separate argument (no "-abc"). This conceptually
# needs only $OPTIND to hold getopts state.
#
# We check that loop does not stop on unknown option (sets "?"),
# stops on _first_ non-option argument.

echo "*** no OPTIND, optstring:'ab' args:-a -b c"
var=QWERTY
while getopts "ab" var -a -b c; do
	echo "var:'$var' OPTIND:$OPTIND"
done
# unfortunately, "rc:0" is shown since while's overall exitcode is "success"
echo "exited: rc:$? var:'$var' OPTIND:$OPTIND"

# Resetting behavior =1
echo "*** OPTIND=1, optstring:'ab' args:-a -b c"
OPTIND=1
while getopts "ab" var -a -b c; do
	echo "var:'$var' OPTIND:$OPTIND"
done
echo "exited: rc:$? var:'$var' OPTIND:$OPTIND"

# Resetting behavior =0
echo "*** OPTIND=0, optstring:'ab' args:-a -b c"
OPTIND=0
while getopts "ab" var -a -b c; do
	echo "var:'$var' OPTIND:$OPTIND"
done
echo "exited: rc:$? var:'$var' OPTIND:$OPTIND"

# Resetting behavior "unset"
echo "*** unset OPTIND, optstring:'ab' args:-a -b c"
unset OPTIND
while getopts "ab" var -a -b c; do
	echo "var:'$var' OPTIND:$OPTIND"
done
echo "exited: rc:$? var:'$var' OPTIND:$OPTIND"

# What is the final exitcode?
echo "*** optstring:'ab' args:-a -b c"
unset OPTIND
getopts "ab" var -a -b c; echo "1 rc:$? var:'$var' OPTIND:$OPTIND"
getopts "ab" var -a -b c; echo "2 rc:$? var:'$var' OPTIND:$OPTIND"
getopts "ab" var -a -b c; echo "3 rc:$? var:'$var' OPTIND:$OPTIND"

# Where would it stop? c or -c?
echo "*** unset OPTIND, optstring:'ab' args:-a c -c -b d"
unset OPTIND
while getopts "ab" var -a c -c -b d; do
	echo "var:'$var' OPTIND:$OPTIND"
done
echo "exited: rc:$? var:'$var' OPTIND:$OPTIND"

# What happens on unknown option?
echo "*** unset OPTIND, optstring:'ab' args:-a -c -b d"
unset OPTIND
while getopts "ab" var -a -c -b d; do
	echo "var:'$var' OPTIND:$OPTIND"
done
echo "exited: rc:$? var:'$var' OPTIND:$OPTIND"

# ORTERR=0 suppresses error message?
echo "*** unset OPTIND, OPTERR=0, optstring:'ab' args:-a -c -b d"
unset OPTIND
OPTERR=0
while getopts "ab" var -a -c -b d; do
	echo "var:'$var' OPTIND:$OPTIND"
done
echo "exited: rc:$? var:'$var' OPTIND:$OPTIND"