piping and backgroud processes (daemons)

demwz · #1 (**permalink**) 06-19-2008

Hello to all,
I've a strage problem here:
a perl script that parses the output of sar -q 300 0 (one line of performace data each 5 min. infinately) works fine from the CLI. It processes one line output every 5 minutes.
If i disconnect it from the terminal (executing it with cron, nohup startporc etc...) no output is processed until sar has completed (using sar -q 1 20).
then all 20 llines output are processed at the same time.

Code

Quote:

open (SAR,"/usr/bin/sar -q 1 4&|") or die "Cant open sar" ;
while (<SAR>){
chomp;
# write the output into a rrd database
}
close (SAR);

the script is supposed to run as "demon" in the backdround to ubdate
performance reports every 5 minutes, so i need to process the output just in time.

As far as i foun out it is not a Perl problem rather than the way linux handels pipes on processes not running on a terminal.

any ideas ?

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
Starting daemons at reboot.	shorty	UNIX for Dummies Questions & Answers	2	04-03-2007 03:10 PM
A doubt on Daemons	marioh	Linux	4	06-21-2005 09:29 AM
Daemons	Pennywize	UNIX for Dummies Questions & Answers	6	02-21-2003 10:43 AM
backgroud process	trynew	UNIX for Advanced & Expert Users	4	07-23-2002 06:53 PM
DNS daemons	Deuce	IP Networking	8	11-29-2001 07:51 AM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Switch to Linear Mode Switch to Hybrid Mode Threaded Mode	Rate This Thread:


	Powered by