The PID (process ID number) being used by IHS will be stored in a file on the server. The IHS configuration file, which is located at ihs_home/conf/httpd.conf, contains the location of the file that contains the PID. In this example, the file is located at ${ihs_home}/logs/httpd.pid

PidFile logs/httpd.pid

Viewing the file that contains the PID will show the PID currently associated with the web server. In this example, the PID is 12345.

~]# cat ihs_home/logs/httpd.pid
12345

Likewise, the ps command can be used to view the PID being used by the web server. In this example, the web server has PID 12345.

~]# ps -ef | grep httpd
nobody  12345  1234  0  07:04  ?  00:00:00 -f /path/to/httpd.conf -k start
nobody  12345  1234  0  07:04  ?  00:00:00 -f /path/to/httpd.conf -k start
nobody  12345  1234  0  07:04  ?  00:00:00 -f /path/to/httpd.conf -k start
nobody  12345  1234  0  07:04  ?  00:00:00 -f /path/to/httpd.conf -k start

The PID is used to control certain things. For example, when the web server is started, it selects a certain PID that is reserved for the web server until the web server is stopped. The PID also controls the files that the web server writes events to.