Hi,
I have a script which wakes up twice every hour 5,30 and looks for any new file and if it finds one, it decompresses it and applies the file to our warm standby database. Now, sometimes when I try and load a big file, it takes one hour to load it and in the meantime, the same script fires again.So, what is a good way to check whether an older instance of the script is already running or not and if it finds one then just exits out??? I tried grepping the script name with ps -ef and then awking the 9th column but if anyone else has the file open for reading and also the file is running then ps -ef script returns two for the search. Please help !!!!!!!!!..............

Regards

Subhas

In your script move the file to another directory, I call mine bla/working
When ,after an hour, the script starts again, it will not find the file, if it does find a file, it will be a new file. When all is complete I move the file to bla/archiv and gzip it . All along I echo results to a bla/log directory.

EZEE!

Create a LOCK file using "echo $$ > $LOCK", so that you can get the process id of the script.
when you enter the script, check if the LOCK file exists, if yes then cat the file and do a ps -ef for that process id. If process is running, just exit. Else create the lock. Once the script completes, remove the lock. If lock file does not already exist when starting, create it and continue. Something like this :-

LOCK=/xyz/file.lck
if [ -f $LOCK ]; then
PID=`cat $LOCK`
PROC=`ps -ef | grep $PID | grep -v grep`
if [ " $PROC" = " " ]; then
echo $$ > $LOCK
else
exit 0
fi
else
echo $$ > $LOCK
fi

Instead of using PID, you can just touch a lock and remove it....but the problem occurs if the script starts, touches a lock and abruptly terminates....all further invoke of the script think that it is already running and exit..

Create a file with no permissions. When the script fires up, set to chmod one of the permission r/w/x, but 1st of all do a test if that permission is set, and fail appropriately.


I used this for all my online programs. For instance set to read, then online programs could see the database but no updates. Set to X, and then no online programs were allowed to run. Normal state would be for W permissions. Lot of possibilities here.

In your script add another function which checks if there are old process running...

insert this function above your script... this function checks process "compress" and if it is still running.. it sleeps and checks again..
until the compressing finished and it will continue the next function..

I hope this will solve your problem..

checkcompress() {
while :
do
ps -ef | grep compress | grep -v grep > /tmp/comsan.txt
if [ -s /tmp/comsan.txt ]; then
echo "DB was still compressing files... Please wait!"
sleep 10
else
return 0
fi
done
}