check wether we are already running

backup.sh

@@ -2,6 +2,19 @@
 
 source functions.sh
 
+pidfile=/var/run/backup_script
+
+if [ -f $pidfile ] ; then
+   pid=$(cat $pidfile)
+   if [ -d /proc/$pid ] ; then
+      myerror 42 "$pid already running"
+   else
+      rm -f $pidfile
+   fi
+fi
+
+echo $$ > $pidfile
+
 function listBackups {
    ls -lrt $1
    exit 0
@@ -37,3 +50,4 @@ for dir in "$@" ; do
   echo cp -a $dir $backupdir
 done
 
+rm -f $pidfile