Change method of determining whether a package is installed

diff --git a/src/plugins/apt.sml b/src/plugins/apt.sml
index 1c31fbd..d2517e9 100644 (file)
--- a/src/plugins/apt.sml
+++ b/src/plugins/apt.sml
@@ -25,6 +25,20 @@ fun validName s = CharVector.all (fn ch => Char.isAlphaNum ch orelse ch = #"_" o
                           
 fun installed name =
     validName name
-    andalso OS.Process.isSuccess (OS.Process.system ("/usr/bin/dpkg -p " ^ name ^ " >/dev/null 2>/dev/null"))
+    andalso let
+       val proc = Unix.execute ("/usr/bin/apt-cache", ["policy", name])
+        val inf = Unix.textInstreamOf proc
+
+       val _ = TextIO.inputLine inf
+    in
+       (case TextIO.inputLine inf of
+            NONE => false
+          | SOME line =>
+            case String.tokens Char.isSpace line of
+                [_, "(none)"] => false
+              | [_, _] => true
+              | _ => false)
+       before ignore (Unix.reap proc)
+    end
 
 end