Bash script works with all arguments except one

Question

I'm on OSX, and I need a bash script that handles multiple arguments. Based on some answers on this website, I wrote the following bash script (some strings have been removed for privacy):

#!/bin/bash

# A POSIX variable
OPTIND=1         # Reset in case getopts has been used previously in the shell.

# Default parameter value:
PORT=xxx
PUBKEY=xxx
HOST_IP=xxx

# show_help function
show_help() {
    echo "Usage: $(basename "$0") [-h] [-p PORT] [-f PUBKEY] [-i HOST_IP]"
    echo
    echo "   -p PORT           add key to container running on port PORT (default: xxx)"
    echo "   -f PUBKEY         add key file PUBKEY (default: xxx)"
    echo "   -i HOST_IP        connect to host HOST_IP (default: xxx)"
    echo
    return
}


while getopts ":h:p:f:i:" option; do
  case "$option" in
    \?)
      echo "invalid argument"
      show_help
      exit 1
      ;;
    h)
      show_help
      exit 0
      ;;
    p)  PORT=$OPTARG
      ;;
    f)  PUBKEY=$OPTARG
      ;;
    i)  HOST_IP=$OPTARG
      ;;
  esac
done

shift $((OPTIND-1))

USER_AT_HOST="root@$HOST_IP"
PUBKEYPATH="$HOME/.ssh/$PUBKEY"
ssh-copy-id -i "$PUBKEYPATH" "$USER_AT_HOST" -p "$PORT"

exit 0

the script works with all arguments (including an invalid argument), except for the argument -h. When I call the script as

script.sh -h

the result is the same as

script.sh

instead of showing me the help. Can you help me understand what's happening?

echo invalid argument >&2; exit 1. Do not show a usage statement in response to an error. Print the error message to stderr and exit non-zero — William Pursell
– William Pursell, Commented Jun 16, 2022 at 18:09
But write a slightly more useful error message like echo "illegal option -$OPTARG (-h for usage)" >&2. It may seem helpful to print a usage statement, but it really isn't. Go to a directory that is not managed by git and type git diff. You will probably (depending on the version) see an irrelevant message telling you about such useful options as --ext-diff and --color-moved-ws and --skip-to, but the useful information that you are not in a git repo has scrolled off the top of the terminal. Keep the error message succinct, relevant, and accurate. Don't give wall of text. — William Pursell
– William Pursell, Commented Jun 16, 2022 at 18:30
@WilliamPursell ok, basically you're suggesting that I remove the call to show_help after echo "invalid argument". Will do — DeltaIV
– DeltaIV, Commented Jun 21, 2022 at 15:36

choroba · Accepted Answer · 2022-06-16 17:27:40Z

3

The : after h in getopts ":h:p:f:i:" means that -h requires an argument, but I don't think -h needs any arguments. Remove the colon after h.

Normally, getopts would display an error:

option requires an argument -- h

But, as you started the string with another colon, error reporting was turned off. Remove the initial : to see the errors in argument processing.

answered Jun 16, 2022 at 17:27

choroba

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markp-fuso · Accepted Answer · 2022-06-16 17:31:43Z

1

In the getopts pattern h: says that -h must have an argument (eg, -h 2) so, have you tried script.sh -h 2?

If -h should not have any args then remove the : after the h leaving you with getopts ":hp:f:i:"

answered Jun 16, 2022 at 17:31

markp-fuso

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