update readme and usage

cli.js

@@ -2,44 +2,21 @@
 'use strict';
 
 const argv = require('minimist')(process.argv.slice(2));
+
 const swm = require('./swm.js');
 const config = require('./config.js');
+const usage = require('./usage.js');
+
 const postCmd = argv.postCmd || config.postCmd;
 const profile = argv.profile || argv.p;
 
+function connectionStatus(device) {
+    return device.connected ? 'Connected' : 'Disconnected';
+}
+
 if (argv.help || argv.h) {
-    console.log(
-`Simple helper for turning on/off connected/disconnected monitors with 'xrandr'.
-
-Usage:
-
-'swm [monitor-1...montior-n] [--postCmd="cmd"]' e.g. 'swm LVDS1 HDMI1'
-
-If 'monitor-1' to 'monitor-n' is specified 'swm' will turn on these monitors
-and place them from left to right in the order given. If a provided monitor is
-not connected it will be skipped.
-
-If no monitors are specified all connected monitors will be turned on and
-placed from left to right in alphabetical order of their name.
-
-If "--postCmd" is given, this command is executed after switching the monitors.
-This is usefull to tell your window manager to re-detect monitors, e.g. for
-herbstluftwm "herbstclient reload".
-
-'swm -l' or 'swm --list'
-
-List all devices with the connectivity status.
-
-The configuration can be placed in "$XDG_CONFIG_HOME/switchmon/config.json" in
-the form of
-
-{
-    "postCmd": "some command"
-}`
-
-    );
-
-    process.exit(2);
+    console.log(usage);
+    process.exit(0);
 }
 
 const devices = swm.getDevices();
@@ -50,7 +27,7 @@ if (argv.list || argv.l) {
             console.log('Detected devices:\n');
             Object.keys(devices)
                 .sort(key => !devices[key].connected)
-                .forEach(key => console.log(key + ':', devices[key].connected ? 'Connected' : 'Disconnected'));
+                .forEach(key => console.log(key + ':', connectionStatus(devices[key])));
             process.exit(0);
         });
 } else {
@@ -73,5 +50,6 @@ if (argv.list || argv.l) {
         .then(swm.executePostCmd.bind(null, postCmd))
         .catch(err => {
             console.error(err);
+            process.exit(2);
         });
 }