getting the pid of the top active window

sammy_aus · 12-19-2009, 04:48 PM

Is there any way to get the pid of the top active window,
and then get all foeils of this id, for example the title of the window,name if the process...

Thanx.

unSpawn · 12-20-2009, 10:43 AM

'xwininfo' gives you some specs but 'xprop' gives you more and including the Process Id. The problem with both is they require you to literally point out the window to use. I wonder if there's a tool that allows for automation since for instance IceWM's "icesh" can do 'icesh -window focus'...

colucix · 12-20-2009, 11:42 AM

You can obtain the ID of the active window using

Code:

xprop -root | awk '/_NET_ACTIVE_WINDOW\(WINDOW\)/{print $NF}'

then you should pass the window ID to another call of xprop using the -id option and looking for the string "_NET_WM_PID(CARDINAL)" to obtain the process ID. Maybe a little tricky, but this should address the doubt raised by unSpawn:

Code:

 xprop -id $(xprop -root | awk '/_NET_ACTIVE_WINDOW\(WINDOW\)/{print $NF}') | awk '/_NET_WM_PID\(CARDINAL\)/{print $NF}'

Moreover, you can use the -display option of xprop in situations where the DISPLAY information is not available to the shell (e.g. if using the xprop command in a script running from crontab).

Another way to obtain the ID of the active window is by means of the xdpyinfo command, for example:

Code:

xdpyinfo | grep focus | grep -E -o 0x[0-9a-f]+

sammy_aus · 12-20-2009, 12:31 PM

thank you,
but i meant getting pid in C/C++

colucix · 12-20-2009, 03:14 PM

Indeed you did not mention the programming language you were deal with, hence the shell was a common guess. Unfortunately, I'm not a C/C++ programmer, so I'm afraid you have to wait for someone more experienced in this topic. In the meanwhile a good starting point could be to look at the source code of the commands mentioned above. You will find them all at x.org.

steve_kam · 01-23-2012, 10:24 AM

I should write a simple java program to pause, resume and kill the process easily by GUI.

@colucix I will get the window id informations from xprop by grapping the window. After that i need to find the process id with these informations but i don't know how. Can you please write me a command which gets window id as parameter, and returns the process id. But this should work for chrome browser which start each tab as a new proces.

Thank you!

kalleanka · 01-24-2012, 05:12 PM

in xlib(warning xlib is messy) I get the topactive window from the windowstack like this:

starting with X_ is the atom of a property.

Code:

Window *get_win_list_stacked(unsigned long *len)
{
    Atom type;
    int form;
    unsigned long remain;
    unsigned char *list;

    errno = 0;
    if(XGetWindowProperty(  global_display,
                            global_root_window,
                            X_NET_CLIENT_LIST_STACKING,
                            0,
                            1024,
                            False,
                            XA_WINDOW,
                            &type,
                            &form,
                            len,
                            &remain,
                            &list)
                        != Success)
    {
        return 0;
    }

    return (Window*)list;
}

int minimized_window(Window win)
{
    Atom type;
    int form;
    unsigned long i, len, remain;
    Atom *atoms;

    atoms = NULL;

    XGetWindowProperty( global_display,
                        win,
                        X_NET_WM_STATE,
                        0,
                        1024,
                        False,
                        XA_ATOM,
                        &type,
                        &form,
                        &len,
                        &remain,
                        (unsigned char**)&atoms);

    for(i=0; i<len; ++i) {
        if(atoms[i]==X_NET_WM_STATE_HIDDEN) {
            XFree(atoms);
            return 1;
        }
    }
    XFree(atoms);
    return 0;
}

int is_skip_taskbar_or_pager_set(Window win)
{
    Atom type;
    int form;
    unsigned long i, len, remain;
    Atom *atoms;

    atoms = NULL;

    XGetWindowProperty( global_display,
                        win,
                        X_NET_WM_STATE,
                        0,
                        1024,
                        False,
                        XA_ATOM,
                        &type,
                        &form,
                        &len,
                        &remain,
                        (unsigned char**)&atoms);

    for(i=0; i<len; ++i)
    {
        if((atoms[i]==X_NET_WM_STATE_SKIP_TASKBAR) || (atoms[i]==X_NET_WM_STATE_SKIP_PAGER))
        {
            XFree(atoms);
            return 1;
        }
    }
    XFree(atoms);
    return 0;
}

Window get_top_window_from_stack()
{
    int i;
    unsigned long len;
    Window *list;
    Window ret;

    ret = 0;

    list = (Window*) get_win_list_stacked(&len);

    for (i = 0; i < (int) len; i++) {
        if (!is_skip_taskbar_or_pager_set((Window) list[i]) && !minimized_window((Window) list[i]))
            ret = list[i];
    }

    XFree(list);

    return ret;
}

then you call need to get the pid using your window id. This might be done with the _NET_WM_PID property(if the wm supports it or the programs sets it. I guess).

otherwise check the source of xprop

devUnix · 01-25-2012, 01:00 AM

colucix ->

Thanks for sharing the commands! They are interesting and are something I did not know about.