Default to watching pwd (.), and complain if there's nothing to watch.

lib/tripwire/cli.rb

@@ -17,30 +17,55 @@ def initialize(args)
       recursive = true
       delay = 1
       option_parser = OptionParser.new do |opt|
-        opt.banner = "Usage: tripwire [options] <command> <filespec>+"
-        opt.on("-e","--exclude <pattern>", String, "a pattern defining files/folders to ignore") do |e|
+        opt.banner = "Usage: tripwire [options] COMMAND [FILESPEC]+"
+        opt.on("-e","--exclude PATTERN", String,
+               "a pattern defining files/folders to ignore") do |e|
           scanner.exclude_patterns << e
         end
-        opt.on("-d","--delay <seconds>", Integer, "number of seconds between each scan (defaults to 1)") do |d|
+        opt.on("-d","--delay SECONDS", Integer,
+               "number of seconds between each scan (defaults to 1)") do |d|
           delay = d
         end
-        opt.on("-q","--quiet", "suppresses output") do
+        opt.on("-q","--quiet",
+               "suppresses output") do
           scanner.quiet = true
         end
-        opt.on("-n","--non-recursive", "tells tripwire *not* to scan folders recursively") do
+        opt.on("-n","--non-recursive",
+               "tells tripwire *not* to scan folders recursively") do
           recursive = false
         end
       end
 
       option_parser.parse!(args)
 
       command = args.shift
-      args.map!{|arg| File.directory?(arg) ? "#{arg}/**/*" : arg} if recursive
+      nothing_to_watch = true
+      args.map! do |arg|
+        if File.exist?(arg)
+          nothing_to_watch = false
+        else
+          STDERR.puts "'#{arg}' doesn't exist."
+        end
+        File.directory?(arg) ? "#{arg}/**/*" : arg
+      end if recursive
+
+      # Enough to run?
+      if command.nil?
+        raise "No command specified.  Please specify a command to run."
+      elsif args.empty?
+        args = ["."]
+        puts "Watching default path '.'"
+      elsif nothing_to_watch
+        STDERR.puts "WARNING: Nothing to watch in '#{args.join(", ")}'"
+      # else good to run
+      end
+
       scanner.scan_patterns.concat(args)
       runner = Tripwire::Runner.new(scanner, command, :delay => delay)
-      runner.run! rescue puts "#{$!}\n(type tripwire -h for help)"
-
+      runner.run!
+    rescue
+      STDERR.puts "#{$!}\n\n#{option_parser}"
     end
 
   end
-end
+end