Run.hs: +2 functions, safeSpawn & unsafeSpawn

See their documentation. This is part of a re-organization of various 'run' commands; this two
make it easier to go through the shell or not, and will be re-used elsewhere.

Run.hs

@@ -20,6 +20,8 @@ module XMonadContrib.Run (
                           -- $usage
                           runProcessWithInput,
                           runProcessWithInputAndWait,
+                          safeSpawn,
+                          unsafeSpawn,
                           seconds
                          ) where
 
@@ -81,3 +83,22 @@ runProcessWithInputAndWait cmd args input timeout = do
 -}
 seconds :: Rational -> Int
 seconds = fromEnum . (* 1000000)
+
+{- | safeSpawn bypasses XMonad's 'spawn' command, because spawn passes strings to /bin/sh to be interpreted as shell
+   commands. This is often what one wants, but in many cases the passed string will contain shell metacharacters
+   which one does not want interpreted as such (URLs particularly often have shell metacharacters like '&' in them).
+   In this case, it is more useful to specify a file or program to be run and a string to give it as an argument so
+   as to bypass the shell and be certain the program will receive the string as you typed it.
+   unsafeSpawn is an alias for XMonad's 'spawn', to remind one that use of it can be, well, unsafe.
+   Examples:
+   >     , ((modMask,               xK_Print ), unsafeSpawn "import -window root png:$HOME/xwd-$(date +%s)$$.png")
+   >     , ((modMask,               xK_d     ), safeSpawn "firefox" "")
+
+   Note that the unsafeSpawn example must be unsafe and not safe because it makes use of shell interpretation by relying on
+   $HOME and interpolation, whereas the safeSpawn example can be safe because Firefox doesn't need any arguments if it is
+   just being started.
+-}
+safeSpawn :: FilePath -> String -> X ()
+safeSpawn prog arg = io (try (forkProcess $ executeFile prog True [arg] Nothing) >> return ())
+unsafeSpawn :: String -> X ()
+unsafeSpawn = spawn