topic Re: Shell error with addition in Operating System - HP-UX

Shell error with addition

marc seguin — Wed, 08 Oct 2003 10:45:25 GMT

With /usr/bin/sh on HP-UX 11.11, i get this strange error :

# typeset -Z2 numero=7
# echo $numero
07
# (( numero = $numero + 1 ))
# echo $numero
08
# (( numero = $numero + 1 ))
sh: 08 + 1 : The specified number is not valid for this command.

Is there a patch for this bug ?

Re: Shell error with addition

Jeff Schussele — Wed, 08 Oct 2003 11:03:55 GMT

Hi Marc,

This has to be due to the -Z.
Try it with -i2 - that defines it as an integer & speeds the math to boot.

HTH,
Jeff

Re: Shell error with addition

john korterman — Wed, 08 Oct 2003 11:10:50 GMT

Hi,
I don't that it is even oficailly recognized as a bug: a numeric string preceded with 0 is interpreted as octal notation. You probaly have to change your variable definition to something like
typeset -i numero=7
and then perform other operations in order to write it with a zero in front.

regards,
John K.

Re: Shell error with addition

Jeff Schussele — Wed, 08 Oct 2003 11:16:50 GMT

Hi John,

The -Z right justifies & pads the value with leading zeros if the first nonblank char is a digit. The pad depends on the n value - in this case 2.
So the 7 is padded to 07.

BUT - I don't *think* it's stored as an integer & I think that's what is causing the "message".

Rgds,
Jeff

Re: Shell error with addition

john korterman — Wed, 08 Oct 2003 11:23:33 GMT

Hi Jeff,
you are probably right. I just thought that the system was protesting against doing an addition to what it considered being the highest octal number.

regards,
John K.

Re: Shell error with addition

marc seguin — Thu, 09 Oct 2003 02:02:48 GMT

I don't agree with your explanations.
If my parameter is to be considered as an octal value, it can't be 8 (or 08). And "07 + 1" would give 10.

With HP-UX 10.20, i don't have this result.
I get :
# typeset -Z2 string=7
# (( string = $string + 1 ))
# echo $string
08
# (( string = $string + 1 ))
# echo $string
09

Which is OK !!

With HP-UX 11.11, i can solve my problem in using two parameters ,one as a string[Z2] and one as an integer. But i don't think it is a normal behaviour.

Re: Shell error with addition

john korterman — Thu, 09 Oct 2003 02:11:06 GMT

Hi again Marc,
I still think the problem is related to the system perceiving "08" as an octal value.
And although I do not like to disagree with Pharaohs I think the problem fits the description for patch PHCO_29699, which holds a reference to patch PHCO_26789:
http://www4.itrc.hp.com/service/cki/patchDocDisplay.do?patchId=PHCO_29699

Please see the "Defect description" and the error message.

regards,
John K.

Re: Shell error with addition

marc seguin — Thu, 09 Oct 2003 02:36:59 GMT

Hi John,
YES ! I understand now. So i was wrong, and it is a normal behaviour. And the Pharoahs are still the Pharoahs !
Since HP-UX 11 accepts ISOC standards... and not HP-UX 10.20.
(( 07 + 1 )) is calculated as an octal value, but the result is put in a string parameter as a decimal value, so i get 08. And (( 08 + 1 )) is impossible as an octal operation.
CQFD

Re: Shell error with addition

Steven Sim Kok Leong — Thu, 09 Oct 2003 03:33:38 GMT

Hi,

If for whatever reasons you do not install the patch, one workaround is to strip the 0 prefix e.g.:

numero=`echo $numero | sed 's/^0//'`

Hope this helps. Regards.

Steven Sim Kok Leong

Re: Shell error with addition

marc seguin — Thu, 09 Oct 2003 03:59:26 GMT

Steve,

if you read the description of the patch, it says that a parameter with a leading 0 is interpreted as an octal number IF you INSTALL this patch.
And i don't need the 'sed' tool for a workaround :
numero=${numero##*0}