Programming

Hi,
i am very new to unix/linux programming. for one of the application i have to change the Terminal width and height. i did try this

if (ioctl (fd, TIOCGWINSZ, &win))
return;
if (y && y >24)
win.ws_row = y;
else
win.ws_row = 24;
if (x && x>80)
win.ws_col = x;
else
win.ws_col = 80;
ioctl (fd, TIOCSWINSZ, &win);


I don't see any change the terminal width and height change.

Could some please help in this regards.. or please forward the links where i can find some info/sample code for this

Regards,
Sunil

If you think you will see the terminal resize itself then no that won' happen. That's because every time the terminal window is resized (by moving it in/out with the mouse) the new values of the struct winsize members are stored by the kernel and a SIGWINCH is generated to all the curently running processes so that they can redraw their interface. The vi editor is a good example of a program that redraws itself when such a signal is received.

You can exercise those ioctl's from the command line with the stty command. "stty -a" will display the current values. Then something like "stty rows 50 cols 132" will set new values. You can confirm that the new value were set by doing another "stty -a".

And that is all it does. It stores that values in a place where any process that needs them can access them. Typically a program like vi will read them once at start up. Then if vi gets a SIGWINCH, it would reread them.

The values are typically set by another program like xterm that is managing a text window. If the user asks xterm to change the window size, xterm will do that, set those values, and send the SIGWINCH.

You are trying to reverse the process. Depending on what program is actually controlling that window, there may be some support for that. xterm has escape sequences that can be sent to it for various things like that. Most people are familiar with the escape sequence to change the window title. Some versions of xterm do indeed have an escape sequence to requesta different window size. If xterm grants the request, you process would recieve the SIGWINCH and should then read the new values. But be aware that the user can override this request. And even if it works, the user may simply resize the window back the way he wants it.