Numeric test when using the conditional operator

Question

In bash, why doesn't this work:

$ echo $((1 -gt 2 ? 3 : 4))
bash: 1 -gt 2 ? 3 : 4: syntax error in expression (error token is "2 ? 3 : 4")

Neither does this:

$ echo $(((1 -gt 2) ? 3 : 4))
bash: (1 -gt 2) ? 3 : 4: missing `)' (error token is "2) ? 3 : 4")

Matthew Flaschen · Accepted Answer · 2010-06-03 06:00:01Z

2

Use:

if [ 1 -gt 2 ]; then
  echo 3
else 
  echo 4
fi

Or:

echo $((2 > 1 ? 1 : 0))

The -gt family is used by the test command, while the operators allowed in $(()) are described here and here. You can't mix and match.

Note from the standard that "only signed long integer arithmetic is required." You need to use bc.

answered Jun 3, 2010 at 5:22

Matthew Flaschen

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1 Comment

Because bash doesn't support floating point. Use the bc command.