MKNOD(2)                      System Calls Manual                     MKNOD(2)

NAME
     mknod, mknodat – make a special file node

SYNOPSIS
     #include <sys/stat.h>

     int
     mknod(const char *path, mode_t mode, dev_t dev);

     int
     mknodat(int fd, const char *path, mode_t mode, dev_t dev);

DESCRIPTION
     The device special file path is created with the major and minor device
     numbers extracted from mode.  The access permissions of path are
     constrained by the umask(2) of the parent process.

     If mode indicates a block or character special file, dev is a
     configuration-dependent specification of a character or block I/O device
     and the superblock of the device.  If mode does not indicate a block
     special or character special device, dev is ignored.

     mknod() requires super-user privileges.

     The mknodat() system call is equivalent to mknod() 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 mknodat() 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
     mknod().

RETURN VALUES
     Upon successful completion, a value of 0 is returned.  Otherwise, a value
     of -1 is returned and errno is set to indicate the error.

ERRORS
     mknod() will fail and the file will be not created if:

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

     [EACCES]           Write permission is denied for the parent directory.

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

     [EDQUOT]           The user's quota of inodes for the file system on
                        which the node is being created has been exhausted.

     [EEXIST]           The named file exists.

     [EFAULT]           Path points outside the process's allocated address
                        space.

     [EINVAL]           One or more of the arguments is invalid.

     [EIO]              An I/O error occurs while making the directory entry
                        or allocating the inode.

     [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 exceeds {NAME_MAX}
                        characters or an entire path name exceeds {PATH_MAX}
                        characters.

     [ENOENT]           A component of the path prefix does not exist or path
                        is an empty string.

     [ENOSPC]           The directory in which the entry for the new node 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 node is being created.

     [ENOTDIR]          A component of the path prefix is not a directory.

     [EPERM]            The process's effective user ID is not super-user.

     [EROFS]            The created node would reside on a read-only file
                        system.

     In addition to the errors returned by the mknod(), the mknodat() 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.

LEGACY SYNOPSIS
     #include <unistd.h>

     The include file has changed.

SEE ALSO
     chmod(2), stat(2), umask(2), compat(5)

HISTORY
     A mknod() function call appeared in Version 6 AT&T UNIX.  The mknodat()
     system call appeared in macOS 13.0.

BSD 4                            June 4, 1993                            BSD 4