---
name: "bind"
section: "2"
platform: "macos"
package: "xnu"
version: "12377.121.6"
release: "macOS 26.5"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/bind/2"
---

# bind(2)

bind a name to a socket

## NAME

**bind** – bind a name to a socket

## SYNOPSIS

**#include \<sys/socket.h\>**

*int*\

**bind**(*int socket*, *const struct sockaddr \*address*, *socklen\_t address\_len*);

## DESCRIPTION

**bind**() assigns a name to an unnamed socket. When a socket is created  with [socket(2)](/socket/2.md) it exists in a name space (address family) but has no name assigned. **bind**() requests that *address* be assigned to the socket.

## NOTES

Binding a name in the UNIX domain creates a socket in the file system that must be deleted by the caller when it is no longer needed (using [unlink(2)](/unlink/2.md)).

The rules used in name binding vary between communication domains. Consult the manual entries in section 4 for detailed information.

## RETURN VALUES

Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and the global integer variable *errno* is set to indicate the error.

## ERRORS

The **bind**() system call will fail if:

- \[EACCES\]

  The requested address is protected, and the current user has inadequate permission to access it.

- \[EADDRINUSE\]

  The specified address is already in use.

- \[EADDRNOTAVAIL\]

  The specified address is not available from the local machine.

- \[EAFNOSUPPORT\]

  *address* is not valid for the address family of *socket*.

- \[EBADF\]

  *socket* is not a valid file descriptor.

- \[EDESTADDRREQ\]

  *socket* is a null pointer.

- \[EFAULT\]

  The *address* parameter is not in a valid part of the user address space.

- \[EINVAL\]

  *socket* is already bound to an address and the protocol does not support binding to a new address. Alternatively, *socket* may have been shut down.

- \[ENOTSOCK\]

  *socket* does not refer to a socket.

- \[EOPNOTSUPP\]

  *socket* is not of a type that can be bound to an address.

The following errors are specific to binding names in the UNIX domain.

- \[EACCES\]

  A component of the path prefix does not allow searching or the node's parent directory denies write permission.

- \[EEXIST\]

  A file already exists at the pathname. [unlink(2)](/unlink/2.md) it first.

- \[EIO\]

  An I/O error occurred while making the directory entry or allocating the inode.

- \[EISDIR\]

  An empty pathname was specified.

- \[ELOOP\]

  Too many symbolic links were encountered in translating the pathname. This is taken to be indicative of a looping symbolic link.

- \[ENAMETOOLONG\]

  A component of a pathname exceeded  {NAME\_MAX} characters, or an entire path name exceeded  {PATH\_MAX} characters.

- \[ENOENT\]

  A component of the path name does not refer to an existing file.

- \[ENOTDIR\]

  A component of the path prefix is not a directory.

- \[EROFS\]

  The name would reside on a read-only file system.

## LEGACY SYNOPSIS

**#include \<sys/types.h\>** **#include \<sys/socket.h\>**

The include file ⟨sys/types.h⟩ is necessary.

## SEE ALSO

[connect(2)](/connect/2.md), [connectx(2)](/connectx/2.md), [getsockname(2)](/getsockname/2.md), [listen(2)](/listen/2.md), [socket(2)](/socket/2.md), [compat(5)](/compat/5.md)

## HISTORY

The **bind**() function call appeared in 4.2BSD.