list Isabelle tools via perl script, which is much faster that bash plumbing, especially on Cygwin;
exclude backup files;

--- a/bin/isabelle	Wed Mar 23 16:42:09 2011 +0100
+++ b/bin/isabelle	Wed Mar 23 20:51:36 2011 +0100
@@ -17,8 +17,6 @@
 ISABELLE_HOME="$(cd "$(dirname "$0")"; cd "$(pwd -P)"; cd ..; pwd)"
 source "$ISABELLE_HOME/lib/scripts/getsettings" || exit 2
 
-splitarray ":" "$ISABELLE_TOOLS"; TOOLS=("${SPLITARRAY[@]}")
-
 
 ## diagnostics
 
@@ -30,19 +28,7 @@
   echo "  Start Isabelle tool NAME with ARGS; pass \"-?\" for tool specific help."
   echo
   echo "  Available tools are:"
-  for DIR in "${TOOLS[@]}"
-  do
-    if [ -d "$DIR" ]; then
-      for TOOL in "$DIR"/*
-      do
-        if [ -f "$TOOL" -a -x "$TOOL" ]; then
-          NAME="$(basename "$TOOL")"
-          DESCRLINE="$(fgrep DESCRIPTION: "$TOOL" | sed -e 's/^.*DESCRIPTION: *//')"
-          echo "    $NAME - $DESCRLINE"
-        fi
-      done
-    fi
-  done
+  perl -w "$ISABELLE_HOME/lib/scripts/tools.pl"
   exit 1
 }
 
@@ -63,10 +49,15 @@
 
 ## main
 
+splitarray ":" "$ISABELLE_TOOLS"; TOOLS=("${SPLITARRAY[@]}")
+
 for DIR in "${TOOLS[@]}"
 do
   TOOL="$DIR/$TOOLNAME"
-  [ -f "$TOOL" -a -x "$TOOL" ] && exec "$TOOL" "$@"
+  case "$TOOL" in
+    *~) ;;
+    *) [ -f "$TOOL" -a -x "$TOOL" ] && exec "$TOOL" "$@" ;;
+  esac
 done
 
 fail "Unknown Isabelle tool: $TOOLNAME"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/scripts/tools.pl	Wed Mar 23 20:51:36 2011 +0100
@@ -0,0 +1,37 @@
+#
+# Author: Makarius
+#
+# tools.pl - list Isabelle tools with description
+#
+
+use strict;
+use warnings;
+
+my @tools = ();
+
+for my $dir (split(":", $ENV{"ISABELLE_TOOLS"})) {
+  if (-d $dir) {
+    if (opendir DIR, $dir) {
+      for my $name (readdir DIR) {
+        my $file = "$dir/$name";
+        if (-f $file and -x $file and !($file =~ /~$/)) {
+          if (open FILE, $file) {
+            my $description;
+            while (<FILE>) {
+              if (!defined($description) and m/DESCRIPTION: *(.*)$/) {
+                $description = $1;
+              }
+            }
+            close FILE;
+            if (defined($description)) {
+              push(@tools, "    $name - $description\n");
+            }
+          }
+        }
+      }
+      closedir DIR;
+    }
+  }
+}
+
+for (sort @tools) { print };