add 'which' function to utils and use for 'iwgetid'

bumblebee/modules/nic.py

@@ -35,6 +35,8 @@ class Module(bumblebee.engine.Module):
                 self._states["include"].append(state)
         self._format = self.parameter("format","{intf} {state} {ip} {ssid}");
         self._update_widgets(widgets)
+        self.iwgetid = bumblebee.util.which("iwgetid")
+
 
     def update(self, widgets):
         self._update_widgets(widgets)
@@ -106,7 +108,7 @@ class Module(bumblebee.engine.Module):
     def get_ssid(self, intf):
         if self._iswlan(intf):
             try:
-                return subprocess.check_output(["iwgetid","-r",intf]).strip().decode('utf-8')
+                return subprocess.check_output([self.iwgetid,"-r",intf]).strip().decode('utf-8')
             except:
                 return ""
         return ""

bumblebee/util.py

@@ -60,4 +60,21 @@ def durationfmt(duration, shorten=False, suffix=False):
 
     return "{}{}".format(res, suf if suffix else "")
 
+def which(program):
+    import os
+    def is_exe(fpath):
+        return os.path.isfile(fpath) and os.access(fpath, os.X_OK)
+
+    fpath, fname = os.path.split(program)
+    if fpath:
+        if is_exe(program):
+            return program
+    else:
+        for path in os.environ["PATH"].split(os.pathsep) + ["/sbin", "/usr/sbin/", "/usr/local/sbin"]:
+            exe_file = os.path.join(path, program)
+            if is_exe(exe_file):
+                return exe_file
+
+    return None
+
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