use rpm/dpkg --version , instead of which

git-svn-id: https://svn.code.sf.net/p/xcat/code/xcat-core/trunk@14656 8638fb3e-16cb-4fca-ae20-7b5d299a9bcd

xCAT/postscripts/ospkgs

@@ -660,7 +660,7 @@ elif ( pmatch "$OSVER" "sles11*" ); then
     fi
 elif ( pmatch "$OSVER" "ubuntu*" ); then
 	# verify dpkg is installed
-	result=`which dpkg`
+	result=`dpkg --version`
 	if [ $? -ne 0 ]; then
 		echo "Please install dpkg on $NODE."
 		exit 1

xCAT/postscripts/otherpkgs

@@ -272,7 +272,7 @@ hasdpkg=0
 supdatecommand="rpm -Uvh --replacepkgs"
 sremovecommand="rpm -ev"
 
-result=`which rpm`
+result=`rpm --version`
 if [ $? -eq 0 ]; then
     hasrpm=1
     result=`rpm -q yum`
@@ -285,7 +285,7 @@ if [ $? -eq 0 ]; then
         fi
     fi 
 else
-    result=`which dpkg`
+    result=`dpkg --version`
     if [ $? -eq 0 ]; then
         hasdpkg=1
 	supdatecommand="dpkg -i"