runwatch module

It's exactly the same as i3status... I even copied the manpage!

i3pystatus/runwatch.py

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+import glob
+import os.path
+
+from i3pystatus import IntervalModule
+
+class RunWatch(IntervalModule):
+    """
+    Expands the given path using glob to a pidfile and checks if the process ID found inside is valid
+    (that is, if the process is running).
+    You can use this to check if a specific application, such as a VPN client or your DHCP client is running.
+
+    Available formatters are {pid} and {name}.
+    """
+
+    format_up = "{name}"
+    format_down = "{name}"
+    color_up = "#00FF00"
+    color_down = "#FF0000"
+    settings = (
+        "format_up", "format_down",
+        "color_up", "color_down",
+        "path", "name",
+    )
+    required = ("path", "name")
+
+    @staticmethod
+    def is_process_alive(pid):
+        return os.path.exists("/proc/{pid}/".format(pid=pid))
+
+    def run(self):
+        with open(glob.glob(self.path)[0], "r") as f:
+            pid = int(f.read().strip())
+
+        if self.is_process_alive(pid):
+            fmt = self.format_up
+            color = self.color_up
+        else:
+            fmt = self.format_down
+            color = self.color_down
+
+        self.output = {
+            "full_text": fmt.format(name=self.name, pid=pid),
+            "color": color,
+            "instance": self.name
+        }