Add possibility to define greeting function, suggested by Chris Miller

darcs-hash:20090216210450-ac50b-9b4f7c5bf45afaf21d51e46ff8c2b11d171fcbf2.gz

doc_src/index.hdr.in

@@ -1256,6 +1256,12 @@ end
 </pre>
 </p>
 
+\subsection greeting Configurable greeting
+
+If a function named fish_greeting exists after initialization, it will
+be run when entering interactive mode. Otherwise,if an environment
+variable named fish_greeting exists, it will be printed.
+
 \subsection event Event handlers
 
 When defining a new function in fish, it is possible to make it into an

share/functions/__fish_config_interactive.fish

@@ -146,13 +146,17 @@ function __fish_config_interactive -d "Initializations that should be performed
 	# Print a greeting 
 	#
 
-	if set -q fish_greeting
-		switch $fish_greeting
-			case ''
-			# If variable is empty, don't print anything, saves us a fork
+	if functions -q fish_greeting
+		fish_greeting
+	else
+		if set -q fish_greeting
+			switch $fish_greeting
+				case ''
+				# If variable is empty, don't print anything, saves us a fork
 		
-			case '*'
-			echo $fish_greeting
+				case '*'
+				echo $fish_greeting
+			end
 		end
 	end