syntax error when using while to loop infinitely in a simple shell script

Question

a simple shell script:

#!/bin/sh
str="hello"
while [ -n $str ]; do
  #do noting, just loop infinitely
done

this script throws an error, like this:

./while.sh: 5: ./while.sh: Syntax error: "done" unexpected

why, and what is the correct way ?

Tom Fenech · Accepted Answer · 2016-04-05 08:43:54Z

2

You need to do something! The shortest thing you can do is this:

#!/bin/sh
str="hello"
while [ -n "$str" ]; do
  :
done

:, a shorthand for true, does nothing and returns success.

By the way, I quoted your string $str, as this is something that you should always do.

answered Apr 5, 2016 at 8:43

Tom Fenech

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