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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_system_plugin_selinux(8) 			SELinux Policy nagios_system_plugin			   nagios_system_plugin_selinux(8)

NAME
nagios_system_plugin_selinux - Security Enhanced Linux Policy for the nagios_system_plugin processes DESCRIPTION
Security-Enhanced Linux secures the nagios_system_plugin processes via flexible mandatory access control. The nagios_system_plugin processes execute with the nagios_system_plugin_t SELinux type. You can check if you have these processes running by executing the ps command with the -Z qualifier. For example: ps -eZ | grep nagios_system_plugin_t ENTRYPOINTS
The nagios_system_plugin_t SELinux type can be entered via the nagios_system_plugin_exec_t file type. The default entrypoint paths for the nagios_system_plugin_t domain are the following: /usr/lib/nagios/plugins/check_log, /usr/lib/nagios/plugins/check_load, /usr/lib/nagios/plugins/check_mrtg, /usr/lib/nagios/plug- ins/check_swap, /usr/lib/nagios/plugins/check_wave, /usr/lib/nagios/plugins/check_procs, /usr/lib/nagios/plugins/check_users, /usr/lib/nagios/plugins/check_flexlm, /usr/lib/nagios/plugins/check_nagios, /usr/lib/nagios/plugins/check_nwstat, /usr/lib/nagios/plug- ins/check_overcr, /usr/lib/nagios/plugins/check_sensors, /usr/lib/nagios/plugins/check_ifstatus, /usr/lib/nagios/plugins/check_mrtgtraf, /usr/lib/nagios/plugins/check_ifoperstatus PROCESS TYPES
SELinux defines process types (domains) for each process running on the system You can see the context of a process using the -Z option to ps Policy governs the access confined processes have to files. SELinux nagios_system_plugin policy is very flexible allowing users to setup their nagios_system_plugin processes in as secure a method as possible. The following process types are defined for nagios_system_plugin: nagios_system_plugin_t Note: semanage permissive -a nagios_system_plugin_t can be used to make the process type nagios_system_plugin_t permissive. SELinux does not deny access to permissive process types, but the AVC (SELinux denials) messages are still generated. BOOLEANS
SELinux policy is customizable based on least access required. nagios_system_plugin policy is extremely flexible and has several booleans that allow you to manipulate the policy and run nagios_system_plugin with the tightest access possible. If you want to deny any process from ptracing or debugging any other processes, you must turn on the deny_ptrace boolean. Enabled by default. setsebool -P deny_ptrace 1 If you want to allow all domains to use other domains file descriptors, you must turn on the domain_fd_use boolean. Enabled by default. setsebool -P domain_fd_use 1 If you want to allow all domains to have the kernel load modules, you must turn on the domain_kernel_load_modules boolean. Disabled by default. setsebool -P domain_kernel_load_modules 1 If you want to allow all domains to execute in fips_mode, you must turn on the fips_mode boolean. Enabled by default. setsebool -P fips_mode 1 If you want to enable reading of urandom for all domains, you must turn on the global_ssp boolean. Disabled by default. setsebool -P global_ssp 1 MANAGED FILES
The SELinux process type nagios_system_plugin_t can manage files labeled with the following file types. The paths listed are the default paths for these file types. Note the processes UID still need to have DAC permissions. nagios_system_plugin_tmp_t FILE CONTEXTS
SELinux requires files to have an extended attribute to define the file type. You can see the context of a file using the -Z option to ls Policy governs the access confined processes have to these files. SELinux nagios_system_plugin policy is very flexible allowing users to setup their nagios_system_plugin processes in as secure a method as possible. STANDARD FILE CONTEXT SELinux defines the file context types for the nagios_system_plugin, if you wanted to store files with these types in a diffent paths, you need to execute the semanage command to sepecify alternate labeling and then use restorecon to put the labels on disk. semanage fcontext -a -t nagios_system_plugin_exec_t '/srv/nagios_system_plugin/content(/.*)?' restorecon -R -v /srv/mynagios_system_plugin_content Note: SELinux often uses regular expressions to specify labels that match multiple files. The following file types are defined for nagios_system_plugin: nagios_system_plugin_exec_t - Set files with the nagios_system_plugin_exec_t type, if you want to transition an executable to the nagios_system_plugin_t domain. Paths: /usr/lib/nagios/plugins/check_log, /usr/lib/nagios/plugins/check_load, /usr/lib/nagios/plugins/check_mrtg, /usr/lib/nagios/plug- ins/check_swap, /usr/lib/nagios/plugins/check_wave, /usr/lib/nagios/plugins/check_procs, /usr/lib/nagios/plugins/check_users, /usr/lib/nagios/plugins/check_flexlm, /usr/lib/nagios/plugins/check_nagios, /usr/lib/nagios/plugins/check_nwstat, /usr/lib/nagios/plugins/check_overcr, /usr/lib/nagios/plugins/check_sensors, /usr/lib/nagios/plugins/check_ifstatus, /usr/lib/nagios/plugins/check_mrtgtraf, /usr/lib/nagios/plugins/check_ifoperstatus nagios_system_plugin_tmp_t - Set files with the nagios_system_plugin_tmp_t type, if you want to store nagios system plugin temporary files in the /tmp directories. Note: File context can be temporarily modified with the chcon command. If you want to permanently change the file context you need to use the semanage fcontext command. This will modify the SELinux labeling database. You will need to use restorecon to apply the labels. COMMANDS
semanage fcontext can also be used to manipulate default file context mappings. semanage permissive can also be used to manipulate whether or not a process type is permissive. semanage module can also be used to enable/disable/install/remove policy modules. semanage boolean can also be used to manipulate the booleans system-config-selinux is a GUI tool available to customize SELinux policy settings. AUTHOR
This manual page was auto-generated using sepolicy manpage . SEE ALSO
selinux(8), nagios_system_plugin(8), semanage(8), restorecon(8), chcon(1), sepolicy(8) , setsebool(8) nagios_system_plugin 14-06-10 nagios_system_plugin_selinux(8)
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