Add expandEnv function and use it in PipeReader family of monitors

expandEnv takes a string and expands the environment variables it can
find. variable substringing (e.g. ${VAR:1} to lop off the first
character) is not supported, but $VAR and ${VAR} formats are, with the
former being delimited by punctuation, but not underscores.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/Plugins/BufferedPipeReader.hs b/src/Plugins/BufferedPipeReader.hs
index 9a7266e..b6cad9d 100644
--- a/src/Plugins/BufferedPipeReader.hs
+++ b/src/Plugins/BufferedPipeReader.hs
@@ -20,6 +20,7 @@ import Control.Concurrent.STM
 import System.IO
 import System.IO.Unsafe(unsafePerformIO)
 
+import Environment
 import Plugins
 import Signal
 
@@ -51,7 +52,8 @@ instance Exec BufferedPipeReader where
 
         reader :: (Int, Bool, FilePath) -> TChan (Int, Bool, String) -> IO ()
         reader p@(to, tg, fp) tc = do
-            openFile fp ReadWriteMode >>= hGetLineSafe >>= \dt ->
+            fp' <- expandEnv fp
+            openFile fp' ReadWriteMode >>= hGetLineSafe >>= \dt ->
                 atomically $ writeTChan tc (to, tg, dt)
             reader p tc