diff --git a/atop.daily b/atop.daily
index c72214c..ac4b3b7 100755
--- a/atop.daily
+++ b/atop.daily
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 CURDAY=`date +%Y%m%d`
 LOGPATH=/var/log/atop
 BINPATH=/usr/bin
@@ -7,15 +7,20 @@ INTERVAL=600		# interval 10 minutes
 
 # verify if atop still runs for daily logging
 #
-if [ -e $PIDFILE ] && ps -p `cat $PIDFILE` | grep 'atop$' > /dev/null
+pid=
+if [ -e $PIDFILE ]; then
+       pid=$(cat $PIDFILE)
+fi
+
+if [ -n "$pid" ] && [ -d /proc/$pid ]
 then
-	kill -USR2 `cat $PIDFILE`       # final sample and terminate
+	kill -USR2 $pid       # final sample and terminate
 
 	CNT=0
 
-	while ps -p `cat $PIDFILE` > /dev/null
+	while [ -d /proc/$pid ]
 	do
-		let CNT+=1
+		CNT=$(($CNT + 1))
 
 		if [ $CNT -gt 5 ]
 		then