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Top Forums Shell Programming and Scripting [SOLVED] Using "$!" to get the PID of the Last Ran Background Process Post 302703341 by mrm5102 on Wednesday 19th of September 2012 03:50:36 PM
Old 09-19-2012
[SOLVED] Using "$!" to get the PID of the Last Ran Background Process

Hello All,

I was looking into creating a script that would be used only to start a Daemon and create a lock file...
F.Y.I. It's for Nagios' NRPE Daemon Plugin...

Anyway when I run the command to start the Daemon (below):
Code:
/usr/local/nagios/bin/nrpe -c /usr/local/nagios/etc/nrpe.cfg -d

And try to get the PID of that Command just ran by adding this to the end of that line above:
Code:
...-c nrpe.cfg & echo $!

The PID it prints out is NOT the PID of the NRPE Daemon. Am I not using the "echo $!" correctly...?

On one of the boxes im trying this on, which is SLES 11.1 (Bash), the PID it prints out is one number
less then what the actual PID of the Daemon is.

For Example:
Code:
 # /usr/local/nagios/bin/nrpe -c /usr/local/nagios/etc/nrpe.cfg -d & echo $!
[1] 27329
27329



# ps -ef | grep [/]usr/local/nagios/bin/nrpe
nagios   27330     1  0 15:20 ?        00:00:00 /usr/local/nagios/bin/nrpe -c /usr/local/nagios/etc/nrpe.cfg -d

I thought maybe it was just a coincidence, so I tried it a few more times, and still it does the same thing.
So I figured I would just implement this one and just subtract 1 from the PID it gives me to
get the real PID, but I then tried this same thing on an AIX server and the actual PID was completely random. So
I decided not to do that (probably wouldn't have been a good idea anyway)...


Does anyone know what I'm doing wrong, or if there is a better way to get this PID (without doing the 'ps -ef | grep ...')..??

Any thoughts would be great!


Thanks in Advance,
Matt
 

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Nagios::Plugin::Config(3pm)				User Contributed Perl Documentation			       Nagios::Plugin::Config(3pm)

NAME
Nagios::Plugin::Config - read nagios plugin .ini style config files SYNOPSIS
# Read given nagios plugin config file $Config = Nagios::Plugin::Config->read( '/etc/nagios/plugins.ini' ); # Search for and read default nagios plugin config file $Config = Nagios::Plugin::Config->read(); # Access sections and properties (returns scalars or arrayrefs) $rootproperty = $Config->{_}->{rootproperty}; $one = $Config->{section}->{one}; $Foo = $Config->{section}->{Foo}; DESCRIPTION
Nagios::Plugin::Config is a subclass of the excellent Config::Tiny, with the following changes: o Repeated keys are allowed within sections, returning lists instead of scalars o Write functionality has been removed i.e. access is read only o Nagios::Plugin::Config searches for a default nagios plugins file if no explicit filename is given to "read()". The current standard locations checked are: /etc/nagios/plugins.ini /usr/local/nagios/etc/plugins.ini /usr/local/etc/nagios /etc/opt/nagios/plugins.ini /etc/nagios-plugins.ini /usr/local/etc/nagios-plugins.ini /etc/opt/nagios-plugins.ini To use a custom location, set a "NAGIOS_CONFIG_PATH" environment variable to the set of directories that should be checked. The first "plugins.ini" or "nagios-plugins.ini" file found will be used. SEE ALSO
Config::Tiny, Nagios::Plugin AUTHORS
This code is maintained by the Nagios Plugin Development Team: <http://nagiosplug.sourceforge.net>. COPYRIGHT and LICENCE Copyright (C) 2006-2007 by Nagios Plugin Development Team This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.14.2 2010-12-03 Nagios::Plugin::Config(3pm)
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