topic Re: problem with global variables in Operating System - HP-UX

problem with global variables

itai weisman — Tue, 22 Mar 2005 07:55:04 GMT

hello everyone,
I'm trying to automate the procedure of adding nodes to my enviorment by writing a script.
for some reason, i'm not able to use global variables, in some parts of the script.
I have no idea why, the global variable {ExitCode} and {NODE_TYPE}, won't be updated in the outside the function.
since NODE_TYPE contains the value for 'mach_type' parameter of opcnode command,
AddToDB function fails, and since ExitCode variable updated on the function is not updated globally, test for {ExitCode} (line 289), that excute from main, succeed (while its suppose to fail)
attached tar file that contains the script and parameter file (if you try to run the script, modify OVO_SERVER parameter - set on line 30
thanks ppl

Re: problem with global variables

Kent Ostby — Tue, 22 Mar 2005 08:02:11 GMT

I know there are problems passing variables between scripts depending on how the shell is forked.

Is the problem that the variable don't make it from the parent to the child or that they aren't returned from the child to the parent ?

If it's that they are not going from the parent to the child, then you may need to manually "source" the variable file (i.e. if it were a global networking variable then add:
. /etc/rc.config.d/netconf to the script).

Hope that helps.

Kent M. Ostby

Re: problem with global variables

itai weisman — Tue, 22 Mar 2005 08:12:47 GMT

hi and thanks,
there are no parsing between scripts, only between diffrent function on the same script.
the thing is, there are varibles that defined first out of the function (globbaly) (1) , than one function use this variable (2), then main proggram use it again (3), and then another function use this variable (4).
sometimes, i see varible that was defined in (2) and won't be recognize at (3) or in (4).

Re: problem with global variables

Rory R Hammond — Wed, 23 Mar 2005 11:12:55 GMT

itai,

I was able to duplicate your problem with the following script.
#
#! /bin/sh
func1()
{
Code=1
return 0
}

func2()
{
Code=2
return 0
}

func3()
{
Code=3
return 0
}

func4()
{
Code=4
func3
return 0
}

for arg in func1 func2 func3 func4
do
$arg | tee -a xxx
echo "${Code}"
done

I was able to make it work with the following changes:

(for arg in func1 func2 func3 func4
do
$arg
echo "${Code}"
done) | tee -a xxx

Hope this helps you in figuring out how to modify your script.

Rory

Re: problem with global variables

itai weisman — Wed, 23 Mar 2005 11:42:35 GMT

hi Rory and thanks,
i don't understand.. where did you put the braces?
(i see a closer after done )
where would you do the return code ( $? ) test?
what about other global parameter that wont be updated? or sometimes being update and sometimes not? maybe i don't use global variable correctly?

Re: problem with global variables

Rory R Hammond — Wed, 23 Mar 2005 12:20:39 GMT

itai,

( for ... done )|tee -a filename

I think the tee is causing a forked process (child) and the child is not able to update the parents variables.

A another solution would be to update the exetcodes to a tmp exitcode file. then read the results from the file.
You would have to remove the file after shell completion or when trapped.

Hope that helps

rory