linux - [Solved-5 Solutions] How to use getopts in bash ? - ubuntu - red hat - debian - linux server - linux pc
Linux - Problem :
How to use getopts in bash ?
Linux - Solution 1:
- getopt is a program that parses command line options in shell scripts.
- It is the enhanced version of older getopts and uses the getopt C library to do its job.
- It is compatible with getopts as long as GETOPT_COMPATIBLE environment variable is set, however some of it best features are not available in compatibility mode.
Linux - Solution 2:
#!/bin/bash
usage() { echo "Usage: $0 [-s <45|90>] [-p <string>]" 1>&2; exit 1; }
while getopts ":s:p:" o; do
case "${o}" in
s)
s=${OPTARG}
((s == 45 || s == 90)) || usage
;;
p)
p=${OPTARG}
;;
*)
usage
;;
esac
done
shift $((OPTIND-1))
if [ -z "${s}" ] || [ -z "${p}" ]; then
usage
fi
echo "s = ${s}"
echo "p = ${p}"click below button to copy the code. By - Linux tutorial - team
Example :
$ ./myscript.sh
Usage: ./myscript.sh [-s <45|90>] [-p <string>]
$ ./myscript.sh -h
Usage: ./myscript.sh [-s <45|90>] [-p <string>]
$ ./myscript.sh -s "" -p ""
Usage: ./myscript.sh [-s <45|90>] [-p <string>]
$ ./myscript.sh -s 10 -p foo
Usage: ./myscript.sh [-s <45|90>] [-p <string>]
$ ./myscript.sh -s 45 -p foo
s = 45
p = foo
$ ./myscript.sh -s 90 -p bar
s = 90
p = barclick below button to copy the code. By - Linux tutorial - team
Linux - Solution 3:
The basic syntax of getopts:
getopts OPTSTRING VARNAME [ARGS...]click below button to copy the code. By - Linux tutorial - team
where:
- OPTSTRING is string with list of expected arguments,
- h - check for option -h without parameters; gives error on unsupported options;
- h: - check for option -h with parameter; gives errors on unsupported options;
- abc - check for options -a, -b, -c; gives errors on unsupported options;
- :abc - check for options -a, -b, -c; silences errors on unsupported options;
Notes: In other words, colon in front of options allows you handle the errors in your code. Variable will contain in the case of unsupported option, in the case of missing value.
- OPTARG - is set to current argument value,
- OPTERR - indicates if Bash should display error messages.
Code:
#!/usr/bin/env bash
p = barclick below button to copy the code. By - Linux tutorial - team
Linux - Solution 4:
The example packaged with getopt /usr/share/getopt/getopt-parse.bash
#!/bin/bash
# A small example program for using the new getopt(1) program.
# This program will only work with bash(1)
# An similar program using the tcsh(1) script language can be found
# as parse.tcsh
# Example input and output (from the bash prompt):
# ./parse.bash -a par1 'another arg' --c-long 'wow!*\?' -cmore -b " very long "
# Option a
# Option c, no argument
# Option c, argument `more'
# Option b, argument ` very long '
# Remaining arguments:
# --> `par1'
# --> `another arg'
# --> `wow!*\?'
# Note that we use `"$@"' to let each command-line parameter expand to a
# separate word. The quotes around `$@' are essential!
# We need TEMP as the `eval set --' would nuke the return value of getopt.
TEMP=`getopt -o ab:c:: --long a-long,b-long:,c-long:: \
-n 'example.bash' -- "$@"`
if [ $? != 0 ] ; then echo "Terminating..." >&2 ; exit 1 ; fi
# Note the quotes around `$TEMP': they are essential!
eval set -- "$TEMP"
while true ; do
case "$1" in
-a|--a-long) echo "Option a" ; shift ;;
-b|--b-long) echo "Option b, argument \`$2'" ; shift 2 ;;
-c|--c-long)
# c has an optional argument. As we are in quoted mode,
# an empty parameter will be generated if its optional
# argument is not found.
case "$2" in
"") echo "Option c, no argument"; shift 2 ;;
*) echo "Option c, argument \`$2'" ; shift 2 ;;
esac ;;
--) shift ; break ;;
*) echo "Internal error!" ; exit 1 ;;
esac
done
echo "Remaining arguments:"
for arg do echo '--> '"\`$arg'" ; doneclick below button to copy the code. By - Linux tutorial - team
Linux - Solution 5:
Save the file as getopt.sh:
#!/bin/bash
function get_variable_name_for_option {
local OPT_DESC=${1}
local OPTION=${2}
local VAR=$(echo ${OPT_DESC} | sed -e "s/.*\[\?-${OPTION} \([A-Z_]\+\).*/\1/g" -e "s/.*\[\?-\(${OPTION}\).*/\1FLAG/g")
if [[ "${VAR}" == "${1}" ]]; then
echo ""
else
echo ${VAR}
fi
}
function parse_options {
local OPT_DESC=${1}
local INPUT=$(get_input_for_getopts "${OPT_DESC}")
shift
while getopts ${INPUT} OPTION ${@};
do
[ ${OPTION} == "?" ] && usage
VARNAME=$(get_variable_name_for_option "${OPT_DESC}" "${OPTION}")
[ "${VARNAME}" != "" ] && eval "${VARNAME}=${OPTARG:-true}" # && printf "\t%s\n" "* Declaring ${VARNAME}=${!VARNAME} -- OPTIONS='$OPTION'"
done
check_for_required "${OPT_DESC}"
}
function check_for_required {
local OPT_DESC=${1}
local REQUIRED=$(get_required "${OPT_DESC}" | sed -e "s/\://g")
while test -n "${REQUIRED}"; do
OPTION=${REQUIRED:0:1}
VARNAME=$(get_variable_name_for_option "${OPT_DESC}" "${OPTION}")
[ -z "${!VARNAME}" ] && printf "ERROR: %s\n" "Option -${OPTION} must been set." && usage
REQUIRED=${REQUIRED:1}
done
}
function get_input_for_getopts {
local OPT_DESC=${1}
echo ${OPT_DESC} | sed -e "s/\([a-zA-Z]\) [A-Z_]\+/\1:/g" -e "s/[][ -]//g"
}
function get_optional {
local OPT_DESC=${1}
echo ${OPT_DESC} | sed -e "s/[^[]*\(\[[^]]*\]\)[^[]*/\1/g" -e "s/\([a-zA-Z]\) [A-Z_]\+/\1:/g" -e "s/[][ -]//g"
}
function get_required {
local OPT_DESC=${1}
echo ${OPT_DESC} | sed -e "s/\([a-zA-Z]\) [A-Z_]\+/\1:/g" -e "s/\[[^[]*\]//g" -e "s/[][ -]//g"
}
function usage {
printf "Usage:\n\t%s\n" "${0} ${OPT_DESC}"
exit 10
}click below button to copy the code. By - Linux tutorial - team
You can use it like this:
#!/bin/bash
#
# [ and ] defines optional arguments
#
# location to getopts.sh file
source ./getopt.sh
USAGE="-u USER -d DATABASE -p PASS -s SID [ -a START_DATE_TIME ]"
parse_options "${USAGE}" ${@}
echo ${USER}
echo ${START_DATE_TIME}