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Full Discussion: [SOLVED] Using "$!" to get the PID of the Last Ran Background Process
Top Forums Shell Programming and Scripting [SOLVED] Using "$!" 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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LEARN ABOUT SUNOS

kcfd

kcfd(1M)						  System Administration Commands						  kcfd(1M)

NAME

       kcfd - kernel-level cryptographic framework daemon

SYNOPSIS

       kcfd

DESCRIPTION

       The  kcfd  daemon  helps  in managing CPU usage by cryptographic operations performed in software by kernel threads. The system utilization
       associated with these threads is charged to the kcfd process. It also does module verification for kernel cryptographic modules.

       Only a privileged user can run this daemon.

       The kcfd daemon is automatically invoked in run level 1, after /usr is mounted. A previously invoked kcfd daemon that is still running must
       be stopped before invoking another kcfd command.

       Manually starting and restarting kcfd is not recommended. If it is necessary to do so, use the cryptoadm(1M) start and stop subcommands.

EXIT STATUS

       The following exit values are returned:

       0

	   Daemon started successfully.

       > 1

	   Daemon failed to start.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsl/SUNWcslx		   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Evolving			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       cryptoadm(1M), attributes(5)

SunOS 5.10							    30 Sep 2003 							  kcfd(1M)
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