MKNOD(2)MKNOD(2)NAMEmknod - make a directory, a special file, or a regular file
SYNOPSIS
#include <sys/stat.h>
int mknod(const char *path, mode_t mode, dev_t dev);
DESCRIPTION
The mknod() function creates a new file named by the path name pointed
to by path. The file type and permissions of the new file are initial‐
ized from mode.
The file type is specified in mode by the S_IFMT bits, which must be
set to one of the following values:
S_IFIFO
fifo special
S_IFCHR
character special
S_IFDIR
directory
S_IFBLK
block special
S_IFREG
ordinary file
The file access permissions are specified in mode by the 0007777 bits,
and may be constructed by a bitwise OR operation of the following val‐
ues:
S_ISUID 04000 Set user ID on execution.
S_ISGID 020#0 Set group ID on execution if # is 7, 5,
3, or 1. Enable mandatory file/record
locking if # is 6, 4, 2, or 0
S_ISVTX 01000 On directories, restricted deletion
flag; on regular files on a UFS file
system, do not cache flag.
S_IRWXU 00700 Read, write, execute by owner.
S_IRUSR 00400 Read by owner.
S_IWUSR 00200 Write by owner.
S_IXUSR 00100 Execute (search if a directory) by
owner.
S_IRWXG 00070 Read, write, execute by group.
S_IRGRP 00040 Read by group.
S_IWGRP 00020 Write by group.
S_IXGRP 00010 Execute by group.
S_IRWXO 00007 Read, write, execute (search) by others.
S_IROTH 00004 Read by others.
S_IWOTH 00002 Write by others
S_IXOTH 00001 Execute by others.
The owner ID of the file is set to the effective user ID of the
process. The group ID of the file is set to the effective group ID of
the process. However, if the S_ISGID bit is set in the parent direc‐
tory, then the group ID of the file is inherited from the parent. If
the group ID of the new file does not match the effective group ID or
one of the supplementary group IDs, the S_ISGID bit is cleared.
The access permission bits of mode are modified by the process's file
mode creation mask: all bits set in the process's file mode creation
mask are cleared (see umask(2)). If mode indicates a block or character
special file, dev is a configuration-dependent specification of a char‐
acter or block I/O device. If mode does not indicate a block special or
character special device, dev is ignored. See makedev(3C).
If path is a symbolic link, it is not followed.
RETURN VALUES
Upon successful completion, mknod() returns 0. Otherwise, it returns
−1, the new file is not created, and errno is set to indicate the
error.
ERRORS
The mknod() function will fail if:
EACCES
A component of the path prefix denies search permis‐
sion, or write permission is denied on the parent
directory.
EDQUOT
The directory where the new file entry is being placed
cannot be extended because the user's quota of disk
blocks on that file system has been exhausted, or the
user's quota of inodes on the file system where the
file is being created has been exhausted.
EEXIST
The named file exists.
EFAULT
The path argument points to an illegal address.
EINTR
A signal was caught during the execution of the mknod()
function.
EINVAL
An invalid argument exists.
EIO
An I/O error occurred while accessing the file system.
ELOOP
Too many symbolic links were encountered in translating
path.
ENAMETOOLONG
The length of the path argument exceeds {PATH_MAX}, or
the length of a path component exceeds {NAME_MAX} while
_POSIX_NO_TRUNC is in effect.
ENOENT
A component of the path prefix specified by path does
not name an existing directory or path is an empty
string.
ENOLINK
The path argument points to a remote machine and the
link to that machine is no longer active.
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 is not a directory.
EPERM
Not all privileges are asserted in the effective set of
the calling process.
EROFS
The directory in which the file is to be created is
located on a read-only file system.
The mknod() function may fail if:
ENAMETOOLONG
Pathname resolution of a symbolic link produced an
intermediate result whose length exceeds {PATH_MAX}.
USAGE
Applications should use the mkdir(2) function to create a directory
because appropriate permissions are not required and because mknod()
might not establish directory entries for the directory itself (.) and
the parent directory (..). The mknod() function can be invoked only by
a privileged user for file types other than FIFO special. The
mkfifo(3C) function should be used to create FIFOs.
Doors are created using door_create(3C) and can be attached to the file
system using fattach(3C). Symbolic links can be created using sym‐
link(2). An endpoint for communication can be created using
socket(3SOCKET).
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌────────────────────┬───────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├────────────────────┼───────────────────┤
│Interface Stability │ Standard │
├────────────────────┼───────────────────┤
│MT-Level │ Async-Signal-Safe │
└────────────────────┴───────────────────┘
SEE ALSOchmod(2), creat(2), exec(2), mkdir(2), open(2), stat(2), symlink(2),
umask(2), door_create(3C), fattach(3C), makedev(3C), mkfifo(3C),
socket(3SOCKET), stat.h(3HEAD), attributes(5), privileges(5), stan‐
dards(5)
Feb 19, 2004 MKNOD(2)
