Looping a perl script in a shell script

Shell Programming and Scripting
1

I am trying to get the follow script to run in the background on the 'fly'. I can launch it via cron and it will run in the background. BUT when I launch it from the command line it will run in the foreground. I figure it has to do with the while loop I have, but I have no clue how I can run the perl script (i didnt write the perl nor have any perl skills at this point) every 5 secs without a loop.

#! /bin/ksh
#

case "$1" in
start)
touch /tmp/vmstat.lk
while [ -f /tmp/vmstat.lk ]
do
su - weblogic -c "/usr/local/scripts/vmstat.pl"
sleep 5
done
;;
stop)
rm /tmp/vmstat.lk
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
;;
esac

exit 0

2

If you want to launch the script into the backround use the ampersand character:

[script] &

3

I've tried that. I am assuming that because I have it set using a start and stop ex:start_vmstat start or start_vmstat stop, that when I add the % it is either ignoring it or it is having no effect.

4

If you want to background what I think you want to background, put your while loop inside parentheses and put an ampersand after the closing parenthesis.

5

using your suggestion I put the () around the while...done adding the % at the end, ended up getting a syntax error % unexpected. I am going to try several variations of what was suggested.

6

% = percent
& = ampersand

7

Also, if you run it as "./script.sh &", it will exit when you close your session. Try runnng it like this:

nohup ./script.sh &

You may have to hit enter to get your shell prompt back, but it should run in the background until you kill it.

8

DOH! thanks for pointing out my mental mistake, my ref source books are using % vs &...got a bit messed up there.

When I placed & in the script I get it to run in the background but get the stty: : No such device or address error.

Using ./script & runs nicely in the background but doesnt allow me to stop it (short of kill)...

You've all given me great advice and I thank you all...going to hack around on this and see if I can get it to play the way I want.

Again Thanks!

9

if you use ./script &

when you get your prompt back you can type "fg" adn it will bring that backgroup process to the fourground then you can control C to stop it.