piping and backgroud processes (daemons) Post: 302207233

Sponsored Content

Top Forums Shell Programming and Scripting piping and backgroud processes (daemons) Post 302207233 by demwz on Thursday 19th of June 2008 11:19:59 AM

06-19-2008

Registered User

piping and backgroud processes (daemons)

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 ?

demwz

View Public Profile for demwz

Find all posts by demwz

9 More Discussions You Might Find Interesting

1. IP Networking

DNS daemons

Does anyone know the command to start the DNS Daemon. I looked in the /etc/init.d/inetsvc file and it tells me what the text should look like. When I go to open the corresponding files they are encoded and I can't read them. So is there a command that will start the DNS daemon? If...

2. UNIX for Advanced & Expert Users

backgroud process

Hi experts How to write a shell program(sh) that running on the backgroud when foreground processing something, such as prompt ....... till the background process finished. thx

3. UNIX for Dummies Questions & Answers

Daemons

MYSQL-daemon don't started automatically by system-start. And same trouble with httpd too. I have SuSE 8.0. What can I do ? Thanks....

4. Linux

A doubt on Daemons

Hi there! I'm a bit curious on something about Daemons.... Supose you have two processes say A and B, where B is a daemon. A is totally independent from B. Is there a way for A to find out B's return code? Is there a way for A to find out when B ends? Thanks!

5. UNIX for Dummies Questions & Answers

Starting daemons at reboot.

I rebooted my server (solaris 5.8) and I had to manually start the cron and mailx daemons. How do I get these to automatically start at reboot? Thanks in advance.

6. Shell Programming and Scripting

daemons definition

hi there, can somebody give me a definition for daemons, or example what are they !! and what the use for? i've done some research and all what i found is /etc/... or /usr/bin/... and i haven't quietly got the concept. any ideas !! Thanks.

7. Shell Programming and Scripting

multiple child scripts running in backgroud, how to use grep on the parent?

Hi I have a shell script A which calls another 10 shell scripts which run in background. How do i make the parent script wait for the child scripts complete, or in other words, i must be able to do a grep of parent script to find out if the child scripts are still running. My Code: ...

8. HP-UX

status of daemons

Hi there all, Hey, is there a way to get the status of all daemons running on a HPUX? in an easy way? Like the same way how to vieuw the status of packages in cmviewcl. Thanks!

9. Shell Programming and Scripting

Running commands in backgroud

I have a small question may be this will be discussed before I have two files file1 and file2 with huge data and I am running the commands as cat file1 |sort & cat file2 |sort & If the session is got disconnected or logout will this command run in background, or shall we use nohup

LEARN ABOUT HPUX

wait

wait(1) 						      General Commands Manual							   wait(1)

NAME

       wait - await process completion

SYNOPSIS

       [pid]

DESCRIPTION

       If  no argument is specified, waits until all processes (started with of the current shell have completed, and reports on abnormal termina-
       tions.  If a numeric argument pid is given and is the process ID of a background process, waits until that process has  completed.   Other-
       wise, if pid is not a background process, exits without waiting for any processes to complete.

       Because the system call must be executed in the parent process, the shell itself executes without creating a new process (see wait(2)).

   Command-Line Arguments
       supports the following command line arguments:

	      The unsigned decimal integer process
			  ID of a command, whose termination is to wait for.

WARNINGS

       Some processes in a 2-or-more-stage pipeline may not be children of the shell, and thus cannot be waited for.

SEE ALSO

       csh(1), ksh(1), sh-posix(1), sh(1), wait(2).

STANDARDS CONFORMANCE

																	   wait(1)