title: How to make a python script run 15 minutes after system startup?
body: <p>I wrote a script a python which reminds me to open WhatsApp Web whenever chrome browser is opened. To run this script each time, I have to use the terminal to make the python script run. I want to make the script run automatically 15-20 minutes after the system starts. </p>
  
  <p>Here's my code:</p>
  
  <pre><code>import webbrowser
  import os
  import signal
  import tkMessageBox
  from subprocess import check_output
  from crontab import CronTab
  
  
  def get_pid(name):
      return int(check_output(["pidof","-s",name]))
  '''Script to open whatsapp web whenever chrome is opened'''
  
  cron=CronTab()
  job=cron.new(command='/usr/bin/echo')
  job.minute.during(1,50).every(1)
  name="chrome"
  if (get_pid(name)):
      webbrowser.open('http://web.whatsapp.com')
      tkMessageBox.showinfo(title="Greetings", message="Connect your         phone to chrome to open whatsapp!")
  </code></pre>
  
  <p>I tried editing the crontab, but that did not prove very helpful. Is there any way to do so?</p>
  
  <p>Edit-1 
  Here's my updated code, and it still doesn't seem to work. When I manually run the script, it works, but otherwise not(on reboot).</p>
  
  <pre><code>    #!/usr/bin/env python
      import webbrowser
  import os
  import signal
  import tkMessageBox
  from subprocess import check_output
  import time
  
  def get_pid(name):
      return int(check_output(["pidof","-s",name]))
  
  
  '''Script to open whatsapp web whenever chrome is opened'''
  
  name="chrome"
  while(1):
      time.sleep(600)
      while(get_pid(name)):
          webbrowser.open('http://web.whatsapp.com')
          tkMessageBox.showinfo(title="Greetings", message="Connect your phone to chrome to open whatsapp!")
          print "Hey"
  </code></pre>
  
  <p>Apart from this, I added the following lines in crontab:</p>
  
  <pre><code>@reboot /usr/bin/python /path/to/whatsapp.py &amp;
  </code></pre>
  
  <p>Further, I made a .conf file which looks like this :</p>
  
  <pre><code>start on runlevel [2345]
  stop on runlevel [!2345]
  
  exec /path/to/whatsapp.py
  </code></pre>
  
  <p>And the most recent log file for this looks like this:</p>
  
  <pre><code>SyntaxError: invalid syntax
  Traceback (most recent call last):
    File "/path/to/whatsapp.py", line 17, in &lt;module&gt;
      while(get_pid(name)):
    File "/path/to/whatsapp.py", line 10, in get_pid
      return int(check_output(["pidof","-s",name]))
    File "/usr/lib/python2.7/subprocess.py", line 573, in check_output
      raise CalledProcessError(retcode, cmd, output=output)
  subprocess.CalledProcessError: Command '['pidof', '-s', 'chrome']' returned non-zero exit status 1
  Traceback (most recent call last):
    File "/path/to/whatsapp.py", line 20, in &lt;module&gt;
      tkMessageBox.showinfo(title="Greetings", message="Connect your phone to chrome to open whatsapp!")
    File "/usr/lib/python2.7/lib-tk/tkMessageBox.py", line 83, in showinfo
      return _show(title, message, INFO, OK, **options)
    File "/usr/lib/python2.7/lib-tk/tkMessageBox.py", line 72, in _show
      res = Message(**options).show()
    File "/usr/lib/python2.7/lib-tk/tkCommonDialog.py", line 44, in show
      w = Frame(self.master)
    File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 2537, in __init__
      Widget.__init__(self, master, 'frame', cnf, {}, extra)
    File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 2049, in __init__
      BaseWidget._setup(self, master, cnf)
    File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 2024, in _setup
      _default_root = Tk()
    File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1767, in __init__
      self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
  _tkinter.TclError: no display name and no $DISPLAY environment variable
  </code></pre>
  
  <p>where path/to is obviously the path to the script. </p>