Simple bash question, -gt: unary operator expected error

Question

Simple script. confused by what is expected in line 2. New to this but feeling like I'm spinning wheels trying to get pseudo code to run.

#!/bin/bash
if [ $a -gt 10 ]
then
  echo "Greater than 10, subtracting 1"
  let a -=1
else
  echo "Less than or equal to 10"
fi

When `a` is empty or unset, the `[ $a -gt 10 ]` becomes `[ -gt 10 ]`, which is invalid — KamilCuk, Feb 11 '20 at 15:36
@OznOg shellcheck.net is big help. Will help improve my questions. — tyro1218, Feb 11 '20 at 17:43

dtc · Answer 1 · 2020-02-11T15:41:08.997

-1

Something like this? I think it was the semicolon you were missing on the if statement. Also, we're assuming $a is defined.

#!/bin/bash
if [ $a -gt 10 ]; then 
  echo "Greater than 10, subtracting 1" 
  let a -=1 
else 
  echo "Less than or equal to 10";
fi

edited Feb 11 '20 at 15:41

answered Feb 11 '20 at 15:35

dtc

The original newlines have been re-enabled, `then` was on its own line originally, so it wasn't this, sorry. – Gem Taylor Feb 11 '20 at 15:39

1 Answers1