shell script to count httpd processes

[Michael Velez]

> -----Original Message-----
> From: redhat-list-bounces at redhat.com 
> [mailto:redhat-list-bounces at redhat.com] On Behalf Of Steve Buehler
> Sent: Monday, March 14, 2005 2:02 PM
> To: redhat-list at redhat.com
> Subject: shell script to count httpd processes
> 
> I am running RHL 7.3.
> I am trying to create a shell script with /bin/sh that will 
> count how many httpd processes are running at the time.
> This is how it would look as a perl script:
> ---start of script---
> #!/usr/bin/perl
> $count = 0;
> @hits = (`ps -afe | grep httpd | grep -v grep`);
>    foreach $entry (@hits) {
>      $count++;
> }
> print "$count\n";
> ---end of script---
> 
> I am trying to do this in an sh script.  Partly for learning 
> partly because I want to do some other things to, but can 
> only know how to do them in a shell script.  Any help would 
> be greatly appreciated.
> 
> Thanks
> Steve
> 
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The following shell script should do the trick:

--- start of script ---
#!/bin/bash

COUNT=`ps -aef | grep httpd | grep -c -v grep`

echo $COUNT
--- end of script ---

If the reason for your question is to understand how to use a for loop, the
following script will also work:

--- start of script ---
#!/bin/bash
PROCIDLIST=`ps -aef | grep httpd | grep -v grep | awk '{print $2}'`
for PROCID in $PROCIDLIST
do
	COUNT=$((COUNT+1))
done

echo $COUNT
--- end of script

Please note there is another syntax for the 'for' command, which looks like
the following:
----
for (( statement1;  statement2;  statement3))
do
	statement block
done
----
The above 'for' syntax works like the 'for' statement in C.

Michael