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Executing External commands on Unix

Posted by smithce (smithce), 7 April 2005
I am 'trying to' execute an external command but without much success:

$ENV{"CCM_ADDR"} = $dbsession;
system("export CCM_ADDR") || die "Cant export CCM_ADDR" ;

The environment variable CCM_ADDR is set properly but the 'export CCM_ADDR does not seem to work ? I have tried all combinations "" `` ''' with no you have any ideas ?

BTW - The op sys is AIX.

Best Regards

Posted by admin (Graham Ellis), 15 April 2005
Your problem's probably not so much with the system command but with export; it'll export to subprocesses  but not to processes at the same level or higher so I suspect that it's working but too limited. system does a fork internally in Perl, with the insitigating process waiting for the subprocess to complete. Thus you're doing the export only in a temporarily available child.

Suggestion - if you give system one scalar argument, which you are doing in this case, and it includes shell metacharacters then it's passed to sh. I'm sure you're setting the environment in preparation for another process.   It should be in that other process if you run it in system after a ";" character - for example:

     system("export TAPE; tar xz demodir");

Posted by smithce (smithce), 15 April 2005

Spot on as usual ...that's great !!

Many Thanks

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