Questions[c](ubuntu)

I am trying to find a way to detect the event of a window (any window) being opened in Ubuntu 16.04

I would like to be able to detect the "window open" event and check if the opened window was my sought window and thereafter run a bash script or a C/C++ function.

So far I've found that I can use wmctrl -l to find which windows are already opened. I could use this command and perhaps grep to find if my sought window is opened and then act on this information.

I'd prefer not to poll, as I'd not want the application to stand idle when the window opens. The action should be as "instantaneous" as possible.

Is there an event or signal I could listen for to achieve this? From the kernel, window manager (Compiz) or maybe some log file that changes?

EDIT: To clarify, I have an application (not under my control) which might show a window at any time, this window does not have a title but it does have the WM_CLASS set (the WM_CLASS is the same for all windows of the application). I want to act upon the event that this window is shown (or created, whichever is best/easier).

It doesn't seem like the window is opened "within" the main applications window. Using xwininfo -children -id <window-id> shows that the main application and the sought window are on different branches, connected to "the root window".

The branches looks like this, where R is "the root node"; A is a root node of the main application's branch and Y is the root of the branch with sought window W:

    R
   / \
  A   Y
 /\    \
B  C    X
    \    \
     Q    W

So I'm hoping that I can find the unique structure of Y-X-W

I'm not sure I have to listen to all windows, but it is my assumption that I'll have to check what happens within "the root window" and try to find the sought window.

I'm using Ubuntu 12.04. I do not have any root or sudo privileges as this is a company machine.

Is there, in a normal installation of Ubuntu 12.04, any terminal program that I can use to turn ugly malformed source code that lacks any indentation into nice looking code?

Again, I can't install any packages so I need one that already comes with Ubuntu, if such a thing exists.

For example:

    int main()
    {
test(1);
another_function(1);
}

And then convert it to:

int main()
{
    test(1);
    another_function(1);
}

I'm a beginner and I'm new to Ubuntu. I just installed it and want to run a C program. I have no idea what platform to use or where to write the code. I need to use the pthread.h header file in the program. Can anyone help me?

I just switched from Windows to Ubuntu 11.10.

I wrote the following code in C with the text editor and saved it as HelloWorld.c in Documents.

#include <stdio.h>
int main()
{
    printf("Hello World!\n");
    return 0;
}

And I started the Terminal and enter the following commands:

cd Documents

gcc HelloWorld.c

A file called a.out, which, after some search on Google, is the executable. I entered this command:

a.out

But I get

a.out: command not found

Which step did I do wrongly?

I want to add my own library to use in c compiling, but don't really know where ubuntu stores it.