diff --git a/scripts/unify-sources.sh b/scripts/unify-sources.sh
--- a/scripts/unify-sources.sh
+++ b/scripts/unify-sources.sh
@@ -212,7 +212,7 @@
     TMP_FILE=`mktemp`
     cat $1 | sed -e 's/ \+$//g' >$TMP_FILE
 
-    "$ACTION"_action "$TMP_FILE" "$1" 'spaces'
+    "$ACTION"_action "$TMP_FILE" "$1" 'trailing spaces'
 }
 
 function long_lines_check() {
@@ -225,7 +225,7 @@
 # process the file
 
 function process_file() {
-    echo -n "    $ACTION " $1...
+    echo -n "    $ACTION $1..."
 
     CHECKING="header tabs spaces long_lines"
 
@@ -259,12 +259,12 @@
   --dry-run|-n
      Check the given files, but do not modify them.
   --interactive|-i
-     If --dry-run is specified and files are warned then a message is
+     If --dry-run is specified and files are warned, then a message is
      prompted whether the warnings should be turned to errors.
   --werror|-w
-     If --dry-run is specified and the warnings are turned to errors.
+     If --dry-run is specified, the warnings are turned to errors.
   --all|-a
-     All files in the repository will be checked.
+     Check all source files in the repository.
   --modified|-m
      Check only the modified source files. This option is proper to
      use before a commit. E.g. all files which are modified or added
@@ -282,36 +282,36 @@
   --help|-h
      Print this help message.
   files
-     The files to check/unify. If no file names are given, the
-     modified source will be checked/unified
-
+     The files to check/unify. If no file names are given, the modified
+     source files will be checked/unified (just like using the
+     --modified|-m option).
 "
         exit 0
     elif [ "$1" == '--dry-run' ] || [ "$1" == '-n' ]
     then
-	[ -n "$ACTION" ] && echo "Invalid option $1" >&2 && exit 1
+	[ -n "$ACTION" ] && echo "Conflicting action options" >&2 && exit 1
 	ACTION=check
     elif [ "$1" == "--all" ] || [ "$1" == '-a' ]
     then
-	[ -n "$FILES" ] && echo "Invalid option $1" >&2 && exit 1
+	[ -n "$FILES" ] && echo "Conflicting target options" >&2 && exit 1
 	FILES=all_files
     elif [ "$1" == "--changed" ] || [ "$1" == '-c' ]
     then
-	[ -n "$FILES" ] && echo "Invalid option $1" >&2 && exit 1
+	[ -n "$FILES" ] && echo "Conflicting target options" >&2 && exit 1
 	FILES=changed_files
     elif [ "$1" == "--modified" ] || [ "$1" == '-m' ]
     then
-	[ -n "$FILES" ] && echo "Invalid option $1" >&2 && exit 1
+	[ -n "$FILES" ] && echo "Conflicting target options" >&2 && exit 1
 	FILES=modified_files
     elif [ "$1" == "--interactive" ] || [ "$1" == "-i" ]
     then
-	[ -n "$WARNING" ] && echo "Invalid option $1" >&2 && exit 1
+	[ -n "$WARNING" ] && echo "Conflicting warning options" >&2 && exit 1
 	WARNING='INTERACTIVE'
     elif [ "$1" == "--werror" ] || [ "$1" == "-w" ]
     then
-	[ -n "$WARNING" ] && echo "Invalid option $1" >&2 && exit 1
+	[ -n "$WARNING" ] && echo "Conflicting warning options" >&2 && exit 1
 	WARNING='WERROR'
-    elif [ $(echo $1 | cut -c 1) == '-' ]
+    elif [ $(echo x$1 | cut -c 2) == '-' ]
     then
 	echo "Invalid option $1" >&2 && exit 1
     else