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I have seen many examples for how to use getopts. But I know very basic of bash and I was not able to to implement it in my situation. I really appreciated if anyone expert can show me the template.

I have a script with minimum 6 and maximum 10 input. Here is a brief description:

script.sh -P passDir -S shadowDir -G groupDir -p password -s shadow

User must provide argument for -P -S -G and if not I must display usage and close the program. If argument are provided I need them to be saved into an appropriate variable.

But -p and -s is optional. However, if there is no -p I should do some tasks and if there is no -s I should do some other tasks and if none of them is there I should do some other tasks. Following is what I have written so far but it stock in the for loop.

#!/bin/bash if [ "$(id -u)" != "0" ]; then echo "Only root may add a user to system" exit 2 else usage() { echo "Usage: $0 [-P <password file path>] [-S <shadow file path>] [-G <group path>]" 1>&2; exit 1; } passDir="" shadowDir="" groupDir="" while getopts ":P:S:G:" inp; do case "${inp}" in P) $passDir = ${OPTARG};; S) $shadowDir = ${OPTARG};; G) $groupDir = ${OPTARG};; *) usage;; esac done echo "${passDir}" echo "${shadowDir}" echo "g = ${groupDir}" fi

At the moment is user does not enter arguments nothing will be shown and if there is arguments it goes inside a loop!

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2 Answers 2

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As I understand it, you are just missing some if statements to handle missing arguments. Consider:

usage() { echo "Usage: $0 [-P <password file path>] [-S <shadow file path>] [-G <group path>]" 1>&2; exit 1; } if [ "$(id -u)" != "0" ]; then echo "Only root may add a user to system" exit 2 fi passDir="" shadowDir="" groupDir="" while getopts "P:S:G:" inp; do_ case "${inp}" in P) passDir=${OPTARG};; S) shadowDir=${OPTARG};; G) groupDir=${OPTARG};; *) usage;; esac done if [ -z "$passDir" ] && [ -z "$shadowDir" ] then # if none of them is there I should do some other tasks echo do some other tasks elif ! [ "$passDir" ] then # if there is no -p I should do some tasks_ echo do some tasks elif ! [ "$shadowDir" ] then #if there is no -s I should do some other tasks echo do some other tasks fi
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I fixed a couple of things in your script. This works for me:

#!/bin/bash if [ "$(id -u)" != "0" ]; then echo "Only root may add a user to system" exit 2 fi usage() { echo "Usage: $0 [-P <password file path>] [-S <shadow file path>] [-G <group path>]" 1>&2 exit 1 } passDir="" shadowDir="" groupDir="" while getopts ":P:S:G:" inp; do case "${inp}" in P) passDir=${OPTARG};; S) shadowDir=${OPTARG};; G) groupDir=${OPTARG};; *) usage;; esac done echo "p = $passDir" echo "s = $shadowDir" echo "g = $groupDir"
  • Assignments must not contain spaces: a=1 works, a = 1 doesn't
  • The variable name should not be prefixed with a $ in an assignment
  • If your if branch contains an exit statement, there's no need to put the rest of your code in the else branch
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Thanks for your answer. I appreciate it. I chose other answer as solution because it explained solution for -s and -p is not provided. Thanks again
@Bernard : Now you have to add the cases for -p password and '-s shadow'. And don't forget to write a helpful usage message.

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