Make the -l option default for check.

Use -xdiff for graphical version.
Merge of master-melb:xfs-cmds:29761a by kenmcd.

  Make the -l option default for check.
  Use -xdiff for graphical version.

common

@@ -20,13 +20,6 @@ _setenvironment
 check=${check-true}
 
 diff=diff
-if [ ! -z "$DISPLAY" ]
-then
-    which xdiff >/dev/null 2>&1 && diff=xdiff
-    which gdiff >/dev/null 2>&1 && diff=gdiff
-    which tkdiff >/dev/null 2>&1 && diff=tkdiff
-    which xxdiff >/dev/null 2>&1 && diff=xxdiff
-fi
 verbose=false
 group=false
 xgroup=false
@@ -112,7 +105,8 @@ check options
     -xfs                test XFS (default)
     -udf                test UDF
     -nfs                test NFS
-    -l			line mode diff [xdiff]
+    -l			line mode diff (default)
+    -xdiff		graphical mode diff
     -n			show me, do not run tests
     -q			quick [deprecated]
     -T			output timestamps
@@ -147,11 +141,22 @@ testlist options
 	    xpand=false
 	    ;;
 
-	-l)	# line mode for diff, not gdiff over modems
-	    diff=diff
+	-l)	# line mode for diff, default now, keep for backward compat
 	    xpand=false
 	    ;;
 
+	-xdiff)	# graphical diff mode
+	    xpand=false
+
+	    if [ ! -z "$DISPLAY" ]
+	    then
+		which xdiff >/dev/null 2>&1 && diff=xdiff
+		which gdiff >/dev/null 2>&1 && diff=gdiff
+		which tkdiff >/dev/null 2>&1 && diff=tkdiff
+		which xxdiff >/dev/null 2>&1 && diff=xxdiff
+	    fi
+	    ;;
+
 	-q)	# "quick", no longer used - always quick :-)
 	    xpand=false
 	    ;;