Bad substitution errors in shell script

Shell Programming and Scripting
1

Hello, I was hoping for a second pair of eyes or a little bit of help figuring out what my error is in a script. I did some searching in the forums and didn't find anything so please forgive me if it a similar problem has been discussed before.

My script accepts normal user arguments; however, the two formats I am using are returning bad substitution errors. I could do fix it the old fashioned way with more code but I would prefer to try to figure out what is wrong with my current syntax.

Here are the snippets from the two formats I am trying to use:

while [ "$1" != "" ]
do
   if [ "${1:0:1}" = "-" ]; then
      case "$1" in
      "-v") echo "$VERSION"
           exit
          ;;
      "-h") #echo help usage
           ;;
      "-s") #do stuff
           shift
          ;;
      *)
           usage "Argument not recognized: $1"
          ;;
      esac
   fi
   shift
done

2nd example:

while [ "${1:0:1}" = "-" ]; do
   case ${1:1:1} in
   "v") echo "$VERSION"
        exit
       ;;
   "h") #echo help usage
        ;;
   "s") #do stuff
        shift
       ;;
   *)
        usage "Argument not recognized: $1"
       ;;
   esac
done

My error code:
[script name] [line_number]: Bad substitution

The line_number corresponds with the done in the loops but it's definitely with the ${1:0:1} syntax, which doesn't make sense because it's valid (at least unless my eyes are missing something).

Thanks for any help I can get!

2

Hi, Jackinthemox, and welcome to the forums.

That type of parameter substring expansion isn't implemented by all shells. Are you certain that the shell that's executing the script supports it?

Regards,
Alister

3

if you are trying to parse the command line maybe you should:

man -k getopt