---
title: "sock_set_opt_flag()"
description: "The sock_set_opt_flag() function sets a specific socket option for the given socket descriptor. It is similar to the setsockopt function in POSIX for the SO_REUSEADDR option."
url: "https://wasix.org/docs/api-reference/wasix/sock_set_opt_flag/"
markdown: "https://wasix.org/docs/api-reference/wasix/sock_set_opt_flag.md"
---

# `sock_set_opt_flag()`

Sets a particular socket setting.

## Description

The `sock_set_opt_flag()` function sets a specific socket option for the given socket descriptor. It is similar to the `setsockopt` function in POSIX for the `SO_REUSEADDR` option.

## Syntax

```ebnf
  ;;; Note: This is similar to `setsockopt` in POSIX for SO_REUSEADDR
  ;;; Sets a particular socket setting
  (@interface func (export "sock_set_opt_flag")
    ;;; Socket descriptor
    (param $fd $fd)
    ;;; Socket option to be set
    (param $sockopt $sock_option)
    ;;; Value to set the option to
    (param $flag $bool)
    (result $error (expected (error $errno)))
  )
```

## Parameters

- `ctx`: A mutable reference to the function environment.
- `sock`: The socket descriptor.
- `opt`: The socket option to be set.
- `flag`: The value to set the option to. Should be either `Bool::True` or `Bool::False`.

## Return Value

The function returns an `Errno` value indicating the outcome of the operation. If the operation is successful, `Errno::Success` is returned. If an error occurs, an appropriate `Errno` value is returned.

## Notes

- The `sock_set_opt_flag()` function sets a particular socket setting for the specified socket descriptor.
- The specific socket setting is determined by the `opt` parameter.
- The value to set the option to is specified by the `flag` parameter, which should be either `Bool::True` or `Bool::False`.
- The function is similar to the `setsockopt` function in POSIX, specifically for setting the `SO_REUSEADDR` option.
- The behavior and limitations of the `sock_set_opt_flag()` function may vary depending on the specific runtime environment and underlying networking implementation. It is important to consult the documentation or specifications of the specific environment to understand its behavior in that context.

---

[Documentation index](https://wasix.org/llms.txt) · [HTML version](https://wasix.org/docs/api-reference/wasix/sock_set_opt_flag/)