<div>
you can do it since it was done in the stone age of Unix. Just create a file .pid file and as long as this file is there you're fine<br />
<br />
Regards<br />
Friedrich
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<div>
Not sure I follow.. can you give an example? To reiterate, the cron job and script is functioning fine, if it does not find the running application it tries to run it, but in testing if I kill the running application, start cron, I see cron run the check script but when I issue a ps -ef it is not running. I even changed the script to 'nohup /usr/src/myapp &amp;' but nothing is ever listed in ps.
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<div>
You may find that your script does not run when started by init or cron. If you do, it will be because the environment (including but not limited to PATH) is rather spartan ( rather more so with cron). The fix for this would be to set up the necessary components of your environment at the start of your script. Once you have done that, your current solution should work, or you could use inittab as Tintin suggests.
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<div>
Ok, I put an entry in inittab as per Tintin's solution. I reread inittab using 'init q' and the process started successfully. When I kill the process why do I not see it start back up as per the respawn action?
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<div>
It's possible that it's respawning rapidly as there is an environment setup missing as per duncan's suggestion.<br />
<br />
Is there anything in /var/log/messages to indicate what's happening?
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<div>
Tintin - you are correct, it is respawning too fast.<br />
<br />
init: id &quot;myapp&quot; respawning too fast: disabled for 5 minutes.<br />
<br />
inittab entry: myapp:3:respawn:/usr/src/m<wbr />yapp/chkmy<wbr />app.sh<br />
<br />
However the application is not reliant upon any environmeny variables. I am calling the .sh script from inittab which checks if myapp is running. Any ideas how to stop it spawning too fast?
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BTW it is starting the app backup successfully which is good, but I'm not sure if I should leave it trying to respawn all the time though!
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You might do well to find out why &quot;occassionaly it will, for some reason, stop running&quot; in the first place. I suspect it relies on the environment more than you realize. Cron would send you an email if there were any output on stderr, so I guess you must be redirecting it. You need to see this error output, and possibly output to stdout unless you capture that elsewhere already. Something like this:<br />
<br />
app:3:respawn:/usr/local/s<wbr />bin/myapp.<wbr />sh<br />
<br />
Contents of /usr/local/sbin/myapp.sh:<br />
<br />
#!/bin/sh<br />
exec 2&gt;&gt;/tmp/myapp.log 1&gt;&amp;2<br />
/usr/local/sbin/myapp<br />
<br />
If it turns out you do need to insert environment-setting commands, you would do that after line 2. You might want to put &quot;env&quot; in there anyway, just so you can see what you're working with.<br />
<br />
Make sure your app is not calling getenv(). Strace won't show that (it might show you the problem anyway though). Try this:<br />
<br />
nm --format=sysv -g /usr/local/sbin/myapp | grep getenv<br />
<br />
If used, you'll see something like:<br />
<br />
getenv@@GLIBC_2.2.5 | &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;| &nbsp; U &nbsp;| &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;FUNC|00000000000000da| &nbsp; &nbsp; |*UND*
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<div>
If myapp is a shell script already, make the above changes to that. Remove any other stderr redirection (2&gt;...). If problems persist, run the actual executable under strace, e.g. if it were called myapp.exe then replace that with &quot;strace /usr/local/sbin/myapp.exe&quot;<wbr />
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<div>
Your inittab entry is incorrect. Change it from<br />
<br />
myapp:3:respawn:/usr/src/m<wbr />yapp/chkmy<wbr />app.sh<br />
<br />
to<br />
<br />
myapp:3:respawn:/usr/local<wbr />/sbin/myap<wbr />p<br />
<br />
With inittab, you don't need chkmyapp.sh. &nbsp;That's the whole idea.
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Ooh well spotted Tintin. Looks like myapp is a directory now, not an application. I think my entry is right at <a href="http:#22064817" rel="ugc">http:#22064817</a>&nbsp;though (not sure if I guessed URL right there)
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<div class="content wysiwyg-content">
I have an appliication that needs to be constantly running. At the moment I start the application by running it from the command line and occassionaly it will, for some reason, stop running and I have to start it again. I have written a script that checks if the application is running and if not start it back up. This works fine if manually run from the command line but ideally needs to be put in cron. When I put it in cron and run the .sh every 1 monute it runs fine (I check the output from cron and see it detects whether the application is running or not) however when it detects the application is not running it does not start it back up again (at least I don't see it when I issue ps-ef). Script output below:<br />
<br />
chkapp.sh :<br />
<br />
#!/bin/bash<br />
ps -ef | grep -v grep | grep myapp<br />
# if not found - equals to 1, start it<br />
if [ $? -eq 1 ]<br />
then<br />
/usr/local/sbin/myapp<br />
else<br />
echo .eq 0 - myapp found - do nothing.<br />
fi<br />
<br />
Cron:<br />
<br />
* * * * * /usr/src/chkapp.sh
</div>
</div>


I have an appliication that needs to be constantly running. At the moment I start the application by running it from the command line and occassionaly it will, for some reason, stop running and I have to start it again. I have written a script that checks if the application is running and if not start it back up. This works fine if manually run from the command line but ideally needs to be put in cron. When I put it in cron and run the .sh every 1 monute it runs fine (I check the output from cron and see it detects whether the application is running or not) however when it detects the application is not running it does not start it back up again (at least I don't see it when I issue ps-ef). Script output below:

chkapp.sh :

#!/bin/bash
ps -ef | grep -v grep | grep myapp
# if not found - equals to 1, start it
if [ $? -eq 1 ]
then
/usr/local/sbin/myapp
else
echo .eq 0 - myapp found - do nothing.
fi

Cron:

* * * * * /usr/src/chkapp.sh

How do you check if process is running and start if not?

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