macros: Fix OnBattery()

Avoid reading /sys file if not existent.

diff --git a/macros.vim b/macros.vim
index 58599670c737d4e4f01f920551b31a873f571155..046e381283aef870c7ebc0b50008867ff8551ecd 100644 (file)
--- a/macros.vim
+++ b/macros.vim
@@ -119,7 +119,9 @@ function OnBattery()
   if has('macunix')
     return match(system('pmset -g batt'), "Now drawing from 'Battery Power'") != -1
   elseif has('unix')
-    return readfile('/sys/class/power_supply/AC/online') == ['0']
+    if filereadable('/sys/class/power_supply/AC/online')
+      return readfile('/sys/class/power_supply/AC/online') == ['0']
+    endif
   endif
   return 0
 endfunction