Make perl script to wait while external process is finish

wrongt has asked for the wisdom of the Perl Monks concerning the following question:

Hi,
I want that perl script while executing to wait for external java process to finish. Can anybody point me to the right place how can i do that? I try with function waitpid($pid,0); but this functions always return in $? = - 1 when i call it with existing process and nonexistent process pid.
Thanks in advance.

Comment on Make perl script to wait while external process is finish

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Re: Make perl script to wait while external process is finish by salva (Canon) on Nov 17, 2011 at 09:28 UTC
Has the java process been launched from the Perl script or externally? Because you can not wait using `waitpid` for a process that is not your child. If it is an external process, your best option will probably be to use some lock over a file that is also locked by the Java process (or a wrapper) while it runs. Alternatively, you can check if it is alive looking on the process table (see Proc::ProccessTable for instance) or if it runs as the same user as the Perl script with `kill 0, $pid` (see kill).	[reply] [d/l] [select]
Re: Make perl script to wait while external process is finish by Anonymous Monk on Nov 17, 2011 at 09:21 UTC
You use the system function, the default thing it does, is wait for the launched process to finish (assuming the process you launch, doesn't launch another and then finishes) Maybe even Proc::Background	[reply]