catstartx.py

#!/usr/bin/env python

import os, sys, time

def find_next_free_x_display(max_tries = 10):
    """ 
    Find the next free X Display by 
    investigating the Xlocks in /tmp
    """   
    for i in range(max_tries):
        try_path = "/tmp/.X" + str(i) + "-lock"
        try:
            with open(try_path,"r"):
                pass
        except:
            return i
    else:
        return -1

def usage():
    """
    Print silly usage
    """
    print("Usage: {0} [-t <sec>] <appname> or when using wine: {0} wine <appname>".format(sys.argv[0]))

def check(cond,msg,exit_rc):
    """
    Abort if condition is false
    """
    if cond:
        print(msg)
        usage()
        sys.exit(exit_rc)

if __name__ == "__main__":
    if len(sys.argv) < 2 :
        usage()
    else:
        timeout = 0
        command = sys.argv[1:]

        # Parse -t option
        if sys.argv[1] == "-t":
            check(len(sys.argv) < 3,"-t needs an argument, Sir.",-1)
            check(len(sys.argv) < 4,"You should also add a command behind -t, Sir.",-2)
            
            try:    timeout = int(sys.argv[2])
            except: check(True,"Cannot convert '" + sys.argv[2] + "' to an integer, Sir.",-3)

            command = sys.argv[3:]

        # Count down if desired
        if timeout > 0:
            print("Will start app in ",end='')
            for second in range(timeout):
                print(str(timeout - second) + "..", end='')
                sys.stdout.flush()
                time.sleep(1)
            print()

        display = find_next_free_x_display()
        if display != -1:
            os.system("xinit $(which " + command[0] + ")" + ' '.join(command[1:]) + " -- :" + str(display))
        else:
            print("Sorry, couldn't find a free X display")