Update README.md

README.md

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 # cluster_cron
 A perlscript that makes it possible to cluster cron via a shared drive
+
+In order to use this you need a shared drive on all servers that is going to be part of the cluster such as afs, glusterfs, nfs or samba.
+
+Install this script somwhere and make sure it is executable. In this example the script will be put in:
+/usr/local/bin/cluster_cron.pl
+
+Next you need to add the script to the crontab of some user which will not be synced on both servers, for example the root user.
+
+The script takes 4 arguments of which two are optional:
+user = the user that gets the cron file synced, in this example we are using a user called cluster
+shared directory = the shared drive you set up previously, in this example the path is /mnt/shareddir
+mode = either 0 for active/passive or 1 for active/active if this argument is not supplied 1 is assumed
+cron spool directory = defaults to /var/spool/cron/crontabs
+
+So as root:
+crontab -e
+
+add this line:
+* * * * * /usr/local/bin/cluster_cron.pl cluster /mnt/shareddir 0 /var/spool/cron/crontabs  >> /mnt/shareddir/cluster.log 2>&1