UNIX for Dummies Questions & Answers

Hello,

In my code I am checking to see if a variable that contains a decimal number is greater than 0 in the following manner:

if [ $i -gt 0 ]
do something
fi

However I am getting the error message (if $i for the current iteration holds 9.6352)

command 9.6352 is not found

How can I rectify this problem?

Thanks,
Guss.

Unless you're using a really new ksh, numeric comparison doesn't work on numbers with decimal points.

Code:

if echo "$i" | awk '($1 <= 0) { exit 1 }'
then
...
fi

This is most definitely not an efficient way to do it! If you have ksh available, try it. Otherwise, better ways might involve transforming the number into something without decimal places so the shell can handle it natively. Perhaps if I knew where this number was coming from and what you were using it for...

see the example below:

Code:

kent$  a=9.6532
kent$  [ $a -gt 0 ] && echo "ok" || echo "wrong"                                                                                         
[: integer expression expected: 9.6532
wrong

kent$  [ ${a%%.*} -gt 0 ] && echo "ok" || echo "wrong"
ok

This test will fail where a < 1.

Huh? Floating point support, what you call numbers with decimal points, has been available in ksh93 since 1993.

If you want to do floating point arithmetic from within a bash script, you need to use an external utility such as bc. See Floating Point Math in Bash

Hi,
I am not sure about the ksh version thing, but it works in my system

Code:

#! /usr/bin/ksh
a=9.2
  if [ $a > 0 ]
    then
   echo "Correct"
 else
   echo "incorrect"
 fi

Moderator's Comments:

Please use code tags

And it'd be nice if more people had that. Unless specifically told otherwise it's safest to assume ksh88.