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

# mkfifoat(2)

make a fifo file

Part of [mkfifo(2)](/mkfifo/2.md).

## NAME

**mkfifo**, **mkfifoat** – make a fifo file

## SYNOPSIS

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

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

*int*\

**mkfifo**(*const char \*path*, *mode\_t mode*););

*int*\

**mkfifoat**(*int fd*, *const char \*path*, *mode\_t mode*);

## DESCRIPTION

**mkfifo**() creates a new fifo file with name *path*. The access permissions are specified by *mode* and restricted by the [umask(2)](/umask/2.md) of the calling process.

The fifo's owner ID is set to the process's effective user ID. The fifo's group ID is set to that of the parent directory in which it is created.

The **mkfifoat**() system call is equivalent to **mkfifo**() except in the case where *path* specifies a relative path. In this case the newly created fifo file is created relative to the directory associated with the file descriptor *fd* instead of the current working directory. If **mkfifoat**() is passed the special value AT\_FDCWD in the *fd* parameter, the current working directory is used and the behavior is identical to a call to **mkfifo**().

## RETURN VALUES

A 0 return value indicates success.  A -1 return value indicates an error, and an error code is stored in *errno*.

## ERRORS

**mkfifo**() will fail and no fifo will be created if:

- \[ENOTSUP\]

  The kernel has not been configured to support fifo's.

- \[ENOTDIR\]

  A component of the path prefix is not a directory.

- \[ENAMETOOLONG\]

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

- \[ENOENT\]

  A component of the path prefix does not exist.

- \[EACCES\]

  Search permission is denied for a component of the path prefix.

- \[ELOOP\]

  Too many symbolic links were encountered in translating the pathname.

- \[EROFS\]

  The named file resides on a read-only file system.

- \[EEXIST\]

  The named file exists.

- \[ENOSPC\]

  The directory in which the entry for the new fifo is being placed cannot be extended because there is no space left on the file system containing the directory.

- \[ENOSPC\]

  There are no free inodes on the file system on which the fifo is being created.

- \[EDQUOT\]

  The directory in which the entry for the new fifo is being placed cannot be extended because the user's quota of disk blocks on the file system containing the directory has been exhausted.

- \[EDQUOT\]

  The user's quota of inodes on the file system on which the fifo is being created has been exhausted.

- \[EIO\]

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

- \[EIO\]

  An I/O error occurred while reading from or writing to the file system.

- \[EFAULT\]

  *Path* points outside the process's allocated address space.

- \[EILSEQ\]

  The filename does not match the encoding rules.

In addition to the errors returned by the **mkfifo**(), the **mkfifoat**() function may fail if:

- \[EBADF\]

  The *path* argument does not specify an absolute path and the *fd* argument is neither AT\_FDCWD nor a valid file descriptor open for searching.

- \[ENOTDIR\]

  The *path* argument is not an absolute path and *fd* is neither AT\_FDCWD nor a file descriptor associated with a directory.

## SEE ALSO

[chmod(2)](/chmod/2.md), [stat(2)](/stat/2.md), [umask(2)](/umask/2.md)

## STANDARDS

The **mkfifo** function call conforms to IEEE Std 1003.1-1988 (“POSIX.1”).