---
name: "mkfifoat"
section: "3"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/mkfifo/3"
---

# mkfifoat(3)

make a FIFO special file (a named pipe)

Part of [mkfifo(3)](/mkfifo/3.md).

## NAME

mkfifo, mkfifoat - make a FIFO special file (a named pipe)

## LIBRARY

Standard C library (*libc*, *-lc*)

## SYNOPSIS

```
#include <sys/types.h>
#include <sys/stat.h>
```

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

**#include \<fcntl.h\>**           /\* Definition of AT\_\* constants \*/ **#include \<sys/stat.h\>**

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

Feature Test Macro Requirements for glibc (see [**feature\_test\_macros**(7)](/feature_test_macros/7.md)):

**mkfifoat**():

```
    Since glibc 2.10:
        _POSIX_C_SOURCE >= 200809L
    Before glibc 2.10:
        _ATFILE_SOURCE
```

## DESCRIPTION

**mkfifo**() makes a FIFO special file with name *path*. *mode* specifies the FIFO's permissions. It is modified by the process's **umask** in the usual way: the permissions of the created file are *(mode & ~umask)*.

A FIFO special file is similar to a pipe, except that it is created in a different way. Instead of being an anonymous communications channel, a FIFO special file is entered into the filesystem by calling **mkfifo**().

Once you have created a FIFO special file in this way, any process can open it for reading or writing, in the same way as an ordinary file. However, it has to be open at both ends simultaneously before you can proceed to do any input or output operations on it. Opening a FIFO for reading normally blocks until some other process opens the same FIFO for writing, and vice versa. See [**fifo**(7)](/fifo/7.md) for nonblocking handling of FIFO special files.

### mkfifoat()

The **mkfifoat**() function operates in exactly the same way as **mkfifo**(), except for the differences described here.

If *path* is relative, then it is interpreted relative to the directory referred to by the file descriptor *dirfd* (rather than relative to the current working directory of the calling process, as is done by **mkfifo**() for a relative pathname).

If *path* is relative and *dirfd* is the special value **AT\_FDCWD**, then *path* is interpreted relative to the current working directory of the calling process (like **mkfifo**()).

If *path* is absolute, then *dirfd* is ignored.

See [**openat**(2)](/openat/2.md) for an explanation of the need for **mkfifoat**().

## RETURN VALUE

On success **mkfifo**() and **mkfifoat**() return 0. On error, -1 is returned and *errno* is set to indicate the error.

## ERRORS

- **EACCES**

  One of the directories in *path* did not allow search (execute) permission.

- **EBADF**

  (**mkfifoat**()) *path* is relative but *dirfd* is neither **AT\_FDCWD** nor a valid file descriptor.

- **EDQUOT**

  The user's quota of disk blocks or inodes on the filesystem has been exhausted.

- **EEXIST**

  *path* already exists. This includes the case where *path* is a symbolic link, dangling or not.

- **ENAMETOOLONG**

  Either the total size of *path* is greater than **PATH\_MAX**, or an individual filename component has a length greater than **NAME\_MAX**. In the GNU system, there is no imposed limit on overall filename length, but some filesystems may place limits on the length of a component.

- **ENOENT**

  A directory component in *path* does not exist or is a dangling symbolic link.

- **ENOSPC**

  The directory or filesystem has no room for the new file.

- **ENOTDIR**

  A component used as a directory in *path* is not, in fact, a directory.

- **ENOTDIR**

  (**mkfifoat**()) *path* is relative and *dirfd* is a file descriptor referring to a file other than a directory.

- **EROFS**

  *path* refers to a read-only filesystem.

## ATTRIBUTES

For an explanation of the terms used in this section, see [**attributes**(7)](/attributes/7.md).

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **mkfifo**(), **mkfifoat**() | Thread safety | MT-Safe |

## VERSIONS

It is implemented using [**mknodat**(2)](/mknodat/2.md).

## STANDARDS

POSIX.1-2008.

## HISTORY

- **mkfifo**()

  POSIX.1-2001.

- **mkfifoat**()

  glibc 2.4. POSIX.1-2008.

## SEE ALSO

[**mkfifo**(1)](/mkfifo/1.md), [**close**(2)](/close/2.md), [**open**(2)](/open/2.md), [**read**(2)](/read/2.md), [**stat**(2)](/stat/2.md), [**umask**(2)](/umask/2.md), [**write**(2)](/write/2.md), [**fifo**(7)](/fifo/7.md)