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Host command fails if there is a database connection

by astroboy (Chaplain)
on Nov 20, 2009 at 03:45 UTC ( #808330=perlquestion: print w/replies, xml ) Need Help??
astroboy has asked for the wisdom of the Perl Monks concerning the following question:

Here's a real weird one. I can successfully invoke SQL*Plus (Oracle's SQL shell) from a Perl script. However, if I create a DBI connection first, it fails. The SQL script, test.sql:
select sysdate from dual; exit
and the perl script:
#!/usr/local/bin/perl use DBI; my $dbh = DBI->connect('DBI:Oracle:', 'scott', 'tiger', {RaiseError => + 1}) || die DBI::errstr; my @cmd = ( 'sqlplus', '-s', 'SCOTT/tiger', '@test.sql' ); my $output = qx{@cmd}; my $retcode = $?; if ($? == -1) { die "Error: $?: $!"; } print $output;
which dies with:
Error: -1: No child processes at ./ line 17.

However if I comment line 4, it works! Now it works for me on an older system. The differences are:

older system: Perl 5.10.0, DBI 1.609,DBD::Oracle.1.23, Centos 5.4, Oracle 11g release 1

new system: Perl 5.10.1, DBI 1.609, DBD::Oracle.1.23, Centos 5.4, Oracle 11g release 2

To try and eliminate Perl, I used the vendor version (5.8) on the new system. The only thing I can guess is that the version of Oracle makes a difference. But before I go to all of the trouble of reinstalling Oracle, I'm wondering if anyone can offer a reason for my problem, and a solution.

Note: the actual code in my app uses IPC::Cmd to handle the external command call (and deal with stderr and stdout, etc). I simply use qx{} the test case above to illustrate the unerlying problem. In the real code, the SQL script runs without error, but the return status is always -1

Replies are listed 'Best First'.
Re: Host command fails if there is a database connection
by mje (Curate) on Nov 20, 2009 at 09:12 UTC

    The Oracle OCI libraries muck around with SIGCHILD which will affect running child processes (which you are when you run sqlplus like that). If you absolutely need to do what you are doing I think you need to reset SIGCHILD back to its default behavior.

    Update: I believe you can stop the oracle libraries doing this by adding BEQUEATH_DETACH=YES to your sqlnet.ora file but I'm not sure of the other affects.

      Thanks for your reply. setting or unsetting BEQUEATH_DETACH had no effect for me, but going via a dedicated server process worked for me - thanks for putting me on the right track!
Re: Host command fails if there is a database connection
by roboticus (Chancellor) on Nov 20, 2009 at 12:54 UTC

    I'm sorry I don't have the answer for you, hopefully the one provided by mje will save the day for you. I just wanted to give you a ++ for stating your problem so clearly.


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