scripts: coccicheck: simplify debug file handling

This commit separates handling unset files and pre-existing files. It
also eliminates a duplicated check for unset files in run_cmd_parmap().

Signed-off-by: Benjamin Philip <benjamin.philip495@gmail.com>
Signed-off-by: Julia Lawall <julia.lawall@inria.fr>

Author: Benjamin-Philip

scripts/coccicheck

@@ -138,7 +138,7 @@ run_cmd_parmap() {
 	if [ $VERBOSE -ne 0 ] ; then
 		echo "Running ($NPROC in parallel): $@"
 	fi
-	if [ "$DEBUG_FILE" != "/dev/null" -a "$DEBUG_FILE" != "" ]; then
+	if [ "$DEBUG_FILE" != "/dev/null" ]; then
                 echo $@>>$DEBUG_FILE
                 $@ 2>>$DEBUG_FILE
         else
@@ -259,13 +259,13 @@ coccinelle () {
 
 }
 
-if [ "$DEBUG_FILE" != "/dev/null" -a "$DEBUG_FILE" != "" ]; then
-	if [ -f $DEBUG_FILE ]; then
-		echo "Debug file $DEBUG_FILE exists, bailing"
-		exit
-	fi
-else
-	DEBUG_FILE="/dev/null"
+if [ "$DEBUG_FILE" = "" ]; then
+    DEBUG_FILE="/dev/null"
+fi
+
+if [ -f $DEBUG_FILE ]; then
+	echo "Debug file $DEBUG_FILE exists, bailing"
+	exit
 fi
 
 if [ "$COCCI" = "" ] ; then