Creating shortcuts to run applications conditionally

Question

I was wondering if it is possible to create a keyboard shortcut to run application if it is not yet running in Ubuntu?

This is a valid example for something like a browser which is normally heavily used, and you wouldn't really want to run another instance of it if there is one running already (rather just activate the window).

possible duplicate of How to use a hotkey shortcut to run a launcher ? — Takkat, Jun 21 '11 at 20:49
@Takkat: I think the "one instance" requirement make this question different from that. — enzotib, Jun 21 '11 at 20:55
I guess you could write a script that launches a browser conditionally. Then how to activate the browser window if it already exists? — Leonid, Jun 21 '11 at 20:56
This is the default for firefox, without the -no-remote option, an already started instance is used. — enzotib, Jun 21 '11 at 20:59
@Leonid Google Chrome, Chromium, and any icons you add to Unity's launcher already do this as well. — ændrük, Jun 21 '11 at 21:34

score 4 · Accepted Answer · edited Apr 13 '17 at 12:25

Save the following script to your home folder as launch_chrome.py:

#!/usr/bin/env python

import subprocess
import wnck
import gtk
import time


screen = wnck.screen_get_default()
while gtk.events_pending():
    gtk.main_iteration()

window_list = screen.get_windows_stacked()

last_active = None
for window in window_list:
    if window.get_application().get_name() == "Google Chrome":
        last_active = window

if last_active:

    timestamp = int(time.time())
    last_active.activate(timestamp)

else:

    subprocess.Popen("google-chrome")

Make the script executable:
```
chmod +x ~/launch_chrome.py
```
Use the command /home/<YOURUSERNAME>/launch_chrome.py when adding a shortcut.

When this shortcut is activated, it will either:

Launch a new Chrome window if there aren't any already running or,
bring the most recently used Chrome window into focus.

I adapted the script to activate sublime text editor, but the issue I have is that the keyboard is not on focus after sublime is activated. Any idea? — Kostanos, Sep 10 '13 at 23:58

score 3 · Answer 2 · edited Apr 13 '17 at 12:24

In Ubuntu there is a package called run-one that is close to what you ask.

I report the description:

 This utility will run just one instance at a time of some command and
 unique set of arguments (useful for cronjobs, eg).

Regarding the keyboard shortcut, see here How to use a hotkey shortcut to run a launcher?.

Regarding the "if there is one running already, just activate the window", I don't know. Not all applications have a window, they may have zero or more than one window. And even in the case of a single window, I don't know of a simple way to map a process to its window.

Creating shortcuts to run applications conditionally

2 Answers2