.sh check for numeric content

[Carl Johnson]

Carl Johnson <carlj at peak.org> writes:

> Carl Johnson <carlj at peak.org> writes:
>
>> vogelke+unix at pobox.com (Karl Vogel) writes:
>>
>>>>> On Thu, 24 Jun 2010 09:24:39 +0800, 
>>>>> Aiza <aiza21 at comclark.com> said:
>>>
>>> A> Receiving a variable from the command line that is suppose to contain
>>> A> numeric values.  How do I code a test to verify the content is numeric?
>>>
>>>    The script below will work with the Bourne or Korn shell.
>>>    Results for "0 1 12 1234 .12 1.234 12.3 1a a1":
>>>
>>>      0 is numeric
>>>      1 is numeric
>>>      12 is numeric
>>>      1234 is numeric
>>>      .12 is numeric
>>>      1.234 is numeric
>>>      12.3 is numeric
>>>      1a is NOT numeric
>>>      a1 is NOT numeric
>>
>> You might want to try testing "123..45".
>> I tried changing:
>>>    if expr "$arg" : "[0-9]*[\.0-9]*$" > /dev/null
>> to:
>>     if expr "$arg" : "[0-9]*\.*[0-9]*$" > /dev/null
>> but it still claims that it is numeric, so *I* must be missing
>> something.
>
> I just realized that I had a stupid mistake there and should have
> used:  
>      if expr "$arg" : "[0-9]*\.[0-9]*$" > /dev/null
And of course that was another stupid mistake that I didn't test
properly.  I really wanted 0 or 1 decimal points, so I wanted '\.\?',
except that FreeBSD expr doesn't recognize '\?'.  I finally ended up
with the following which seems to work as *I* expected it to work:
    if expr "$arg" : "[1-9]*\.\{0,1\}[0-9]*$" > /dev/null

-- 
Carl Johnson		carlj at peak.org