I'm trying to start an application within Ubuntu (xfce or gnome) and via the command line and was wondering if there's a generic way to set the dimensions of a given window of a given app that is currently running?


This is easier to do if you install something like xdotool. Then you can do:

xdotool search --name "window name" windowsize 300 400

replace "window name" with a name or reg ex appearing in the window title (you can also search by window class and a variety of other things), and the two numbers appearing after windowsize are the width and height, respectively. (You can also use percents, etc.) See man xdotool once it's installed.

If you're on Lucid or earlier, I recommend going to the xdotool website to get a newer version, however.

To resize Firefox, for example:

xdotool search --name "Mozilla Firefox" windowsize 1024 768
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    is there any way how to resize fullscreen window without decorations (title bar)? And set exact position on screen (e.g. x=0, y=0)? I am trying to set this for maximized mplayer to go to 800x600 x=0 y=0 and then after few minutes to the same fullscreen mode. thanks – peter Mar 27 '16 at 10:28
  • Note that this won't appear to do anything if the window is maximized. – mlissner Dec 13 '19 at 0:06
  • Set position on screen to (0, 0) using xdotool search --name "window name" windowmove 0 0 – Simon Biber Jan 6 at 8:01

If the window manager supports Xlib there is. This uses Python to set the window's size to 500x300:

WIDTH, HEIGHT = 500, 300
import Xlib
import Xlib.display

display = Xlib.display.Display()
root = display.screen().root
windowID = root.get_full_property(display.intern_atom('_NET_ACTIVE_WINDOW'), Xlib.X.AnyPropertyType).value[0]
window = display.create_resource_object('window', windowID)
window.configure(width = WIDTH, height = HEIGHT)

The hard part is getting the window ID; in the above code it got the ID of the active window. If you want another ID, you can use something like this to get the title and controlling PID of each window, and choose the right ID based on those:

windowIDs = root.get_full_property(display.intern_atom('_NET_CLIENT_LIST'), Xlib.X.AnyPropertyType).value
for windowID in windowIDs:
    window = display.create_resource_object('window', windowID)
    name = window.get_wm_name() # Title
    prop = window.get_full_property(display.intern_atom('_NET_WM_PID'), Xlib.X.AnyPropertyType)
    pid = prop.value[0] # PID
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  • Xlib available here: sourceforge.net/projects/python-xlib/?source=typ_redirect – khaverim Mar 5 '17 at 3:01
  • when I do print pid I get <Xlib.protocol.request.GetProperty serial = 15, data = {'bytes_after': 0, 'property_type': 6, 'value': (32, array('I', [5810L])), 'sequence_number': 15}, error = None> ... any suggestion to isolate the actual PID? – khaverim Mar 5 '17 at 3:33
  • Nvm. Doesn't seem to be possible but I can do a workaround via name. – khaverim Mar 5 '17 at 3:38
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    @khaverim Hmm. I think this API changed since I last wrote it, that used to just be the PID. I updated the answer, you want to take the value returned by get_full_property and do .value[0] (value is an array) – Michael Mrozek Mar 5 '17 at 9:59
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    python Xlib can be installed via: sudo apt-get install python-xlib (on Ubuntu) – Tom Jun 6 '19 at 18:17

Specific to XFCE there is pyxfce which will allow you to do that using python language. Pyxfce is an API that, among other things, lets you communicate with the window manager. To use this from the command line would require you to prepare a script first.

Depending on your use, the importance of using a X-based API using X window IDs (such as python-xlib or xdotools mentioned in another answer) versus others that use strings matching window titles (like wmctrl), is that there can be no confusion between windows, which may have the same keywords in their respective title.

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#get window pid under mouse
xprop -id $(xwit -current -print | cut -d ":" -f 1) | grep _NET_WM_PID | cut -d "=" -f2 | cut -c 2-
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I found wmctrl suited me best. It is available as a smallish package, for Ubuntu and for Raspbian, and likely for other distros too.

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    We have an answer that mentions wmctrl, but we don't have an Answer that shows how to use it; could you expand your answer with a demonstration, just so people can then take it and adapt it for their particular use? Thank you! – Jeff Schaller Apr 27 '19 at 20:38
  • Had I had an example at hand, I had certainly added it. Still, isn't that what manpages are for? – Karel Adams Apr 29 '19 at 6:17
  • @KarelAdams No, manuals tells you how a utility works. Manuals don't usually say how to apply a utility to a given situation. Adding an example that is relevant to (or even better, directly applicable to) the user's question is important. – Kusalananda Mar 10 at 17:12

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