int mkfifo(const char *path, mode_t mode);
int mkfifoat(int fd, const char *path, mode_t mode);
IEEE Std 1003.1-2017
mkfifo() function shall create a new
FIFO special file named by the pathname pointed to by path. The file
permission bits of the new
FIFO shall be initialized from mode. The file permission bits of the mode argument shall
be modified by the process' file creation mask.
When bits in mode other than the file permission bits are set, the effect is implementation-defined.
If path names a symbolic link,
mkfifo() shall fail and set
FIFO's user ID shall be set to the process' effective user ID. The
FIFO's group ID shall be set to the group ID of the
parent directory or to the effective group ID of the process. Implementations shall provide a way to initialize the
FIFO's group ID
to the group ID of the parent directory. Implementations may, but need not, provide an implementation-defined way to initialize the
FIFO's group ID to the effective group ID of the calling process.
Upon successful completion,
mkfifo() shall mark for update the last data access, last data modification, and last file
status change timestamps of the file. Also, the last data modification and last file status change timestamps of the directory that
contains the new entry shall be marked for update.
mkfifoat() function shall be equivalent to the
mkfifo() function except in the case where path
specifies a relative path. In this case the newly created
FIFO is created relative to the directory associated with the file
descriptor fd instead of the current working directory. If the access mode of the open file description associated with the
file descriptor is not
O_SEARCH, the function shall check whether directory searches are permitted using the current permissions of
the directory underlying the file descriptor. If the access mode is
O_SEARCH, the function shall not perform the check.
mkfifoat() is passed the special value
AT_FDCWD in the fd parameter, the current working directory shall be
used and the behavior shall be identical to a call to
Upon successful completion, these functions shall return
0. Otherwise, these functions shall return
-1 and set
indicate the error. If
-1 is returned, no FIFO shall be created.
These functions shall fail if:
EACCES- A component of the path prefix denies search permission, or write permission is denied on the parent directory of the
FIFOto be created.
EEXIST- The named file already exists.
ELOOP- A loop exists in symbolic links encountered during resolution of the path argument.
ENAMETOOLONG- The length of a component of a pathname is longer than
ENOENT- A component of the path prefix of path does not name an existing file or path is an empty string.
ENOTDIR- The path argument contains at least one non-
<slash>character and ends with one or more trailing
<slash>characters. If path without the trailing
<slash>characters would name an existing file, an
ENOENTerror shall not occur.
ENOSPC- The directory that would contain the new file cannot be extended or the file system is out of file-allocation resources.
ENOTDIR- A component of the path prefix names an existing file that is neither a directory nor a symbolic link to a directory.
EROFS- The named file resides on a read-only file system.
mkfifoat() function shall fail if:
EACCES- The access mode of the open file description associated with fd is not
O_SEARCHand the permissions of the directory underlying fd do not permit directory searches.
EBADF- The path argument does not specify an absolute path and the fd argument is neither
AT_FDCWDnor a valid file descriptor open for reading or searching.
ENOTDIR- The path argument is not an absolute path and fd is a file descriptor associated with a non-directory file.
These functions may fail if:
ELOOP- More than
SYMLOOP_MAXsymbolic links were encountered during resolution of the path argument.
ENAMETOOLONG- The length of a pathname exceeds
PATH_MAX, or pathname resolution of a symbolic link produced an intermediate result with a length that exceeds