---
name: "tcgetwinsize"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/tcgetwinsize"
---

# tcgetwinsize(3)

get, set the size of a terminal window

## NAME

**tcgetwinsize**, **tcsetwinsize** – get, set the size of a terminal window

## LIBRARY

Standard C Library (libc, -lc)

## SYNOPSIS

**#include \<termios.h\>**

```
struct winsize {
	unsigned short	ws_row;		/* number of rows, in characters */
	unsigned short	ws_col;		/* number of columns, in characters */
	unsigned short	ws_xpixel;	/* horizontal size, in pixels */
	unsigned short	ws_ypixel;	/* vertical size, in pixels */
};
```

*int*\

**tcgetwinsize**(*int fd*, *struct winsize \*w*);

*int*\

**tcsetwinsize**(*int fd*, *const struct winsize \*w*);

## DESCRIPTION

The **tcgetwinsize**() function gets the terminal window size of the terminal of which *fd* is an open file descriptor and stores it in the *winsize* structure of which *w* is a pointer.

The **tcsetwinsize**() function sets the terminal window size of the terminal of which *fd* is an open file descriptor from the *winsize* structure referenced by *w*. The change occurs immediately. If the terminal window size of the terminal is changed successfully to have a value that is different from the value that it had before the **tcsetwinsize**() call, then the SIGWINCH signal is sent to all those members of the foreground process group of the terminal that have the terminal as their controlling terminal.

The above declaration of *struct winsize* may not be literal. It is provided only to list the accessible members. Therefore, before calling **tcsetwinsize**(), the members of the *winsize* structure must be initialized by calling **tcgetwinsize**(). The information in a *winsize* structure is stored by the kernel in order to provide a consistent interface, but it is not used by the kernel.

## RETURN VALUE

The **tcgetwinsize()** and **tcsetwinsize()** functions return the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error. The terminal window size remains unchanged if **tcsetwinsize**() fails.

## ERRORS

The following are the possible failure conditions:

- \[EBADF\]

  The *fd* argument to **tcgetwinsize**() or to **tcsetwinsize**() is not a valid file descriptor.

- \[ENOTTY\]

  The *fd* argument to **tcgetwinsize**() or to **tcsetwinsize**() is not associated with a character special device.

- \[EINVAL\]

  The *w* argument to **tcsetwinsize**() is not valid.

- \[EFAULT\]

  The *w* argument to **tcgetwinsize**() or to **tcsetwinsize**() points outside the process's allocated address space.

## SEE ALSO

[stty(1)](/stty/1.md), [ioctl(2)](/ioctl/2.md), [sigaction(2)](/sigaction/2.md), [termios(4)](/termios/4.md), [tty(4)](/tty/4.md)

## STANDARDS

The **tcgetwinsize**() and **tcsetwinsize**() functions are expected to conform to IEEE Std 1003.1 (“POSIX.1”) Base Specifications, Issue 8. The *ws\_xpixel* and *ws\_ypixel* members of *struct winsize* are FreeBSD extensions.