CODEWITHSUNDEEP
bash
gwizzo
gwizzo

Reputation: 41

Bash switch case statement keeps failing to parse arguments, but pattern matching looks fine?

I am studying a simple bash script, or what I thought would be simple. It looks as though it is simply trying to store the first argument as a variable before proceeding.

However, it fails every time.

Script:

while [ $# -gt 0 ]; do
  case "$1" in
      variableName=*)
      variableName="${1#*=}"
      ;;
    *)
      echo "***************************"
      echo "* Invalid argument:"
      echo "* ($1)"
      echo "***************************"
      exit 1
  esac
  shift
done

Now, if I try to execute it, this happens:

$ sh script.sh "test"
***************************
* Invalid argument:
* (test)
***************************

The pattern match is *, so that looks like it should match anything. At that point, it should simply be storing the variable, and that's it.

In the non-dissected script, there are other variables being stored which proceed this one, hence the loop.

Upvotes: 1

Views: 293

Answers (2)

chepner
chepner

Reputation: 532418

Your pattern is variablename=*, not *. Your argument doesn't start with variablename=, so that case fails.

Upvotes: 0

Michael Kopp
Michael Kopp

Reputation: 1711

If you run your code with the argument variableName=xx it will not go into the Invalid argument condition. Add a echo foo in the line above the ;; and you will see this.

In the end of the script, the variable variableName will be set to the value you passed in, i.e. xx in this case.

The following snipped is your code plus some echo statements which hopefully clearly show, what's going on.

while [ $# -gt 0 ]; do
  case "$1" in
      variableName=*)
      variableName="${1#*=}"
      echo "setting variableName to $variableName"
      ;;
    *)
      echo "***************************"
      echo "* Invalid argument:"
      echo "* ($1)"
      echo "***************************"
      exit 1
  esac
  shift
done

echo "variableName is set to $variableName"

Upvotes: 1

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