MKFIFO(2)                     System Calls Manual                    MKFIFO(2)

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) 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), stat(2), umask(2)

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

macOS 15.2                       June 4, 1993                       macOS 15.2