Terminal control/Dimensions: Difference between revisions

=={{header|C}}==

C provides no standard way to find the size of a terminal.

Some devices can do NAWS (Negotiate About Window Size). A terminal emulator like xterm(1) should set the size. A network server like sshd(1) should copy the size from its client. Other devices, such as plain serial ports, might not know the window size.

[[BSD]] systems (and some other [[Unix]] clones) have TIOCGWINSZ. This ioctl(2) call gets the "window size" of a tty(4) device.

{{libheader|BSD libc}}

{{works with|OpenBSD|4.9}}

<lang c>#include <sys/ioctl.h> /* ioctl, TIOCGWINSZ */

#include <err.h> /* err */

#include <fcntl.h> /* open */

#include <stdio.h> /* printf */

#include <unistd.h> /* close */

int

main()

{

struct winsize ws;

int fd;

/* Open the controlling terminal. */

fd = open("/dev/tty", O_RDWR);

if (fd < 0)

err(1, "/dev/tty");

/* Get window size of terminal. */

if (ioctl(fd, TIOCGWINSZ, &ws) < 0)

err(1, "/dev/tty");

printf("%d rows by %d columns\n", ws.ws_row, ws.ws_col);

printf("(%d by %d pixels)\n", ws.ws_xpixel, ws.ws_ypixel);

close(fd);

return 0;

}</lang>