System Calls mknod(2)
NAME
mknod, mknodat - make a directory, a special file, or a reg-
ular fileSYNOPSIS
#include
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 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 initialized 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 the0007777 bits, and may be constructed by a bitwise OR opera-
tion of the following values: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/recordlocking 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.
SunOS 5.11 Last change: 6 Jul 2010 1
System Calls mknod(2)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 ofthe process. The group ID of the file is set to the effec-
tive group ID of the process. However, if the S_ISGID bit
is set in the parent directory, 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 thesupplementary 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 specialfile, dev is a configuration-dependent specification of a
character 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. Upon successful completion, mknod() marks 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 is marked for update. Only a process with appropriate privileges may invoke
mknod() for file types other than FIFO-special.
The mknodat() function is equivalent to the mknod() function
except in the case where path specifies a relative path. Inthis case the newly created directory, special file, or reg-
ular file is located relative to the directory associatedSunOS 5.11 Last change: 6 Jul 2010 2
System Calls mknod(2) with the file descriptor fd instead of the current working directory. If the file descriptor was opened withoutO_SEARCH, the function checks whether directory searches are
permitted using the current permissions of the directory underlying the file descriptor. If the file descriptor wasopened with O_SEARCH, the function does not perform the
check.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, mknod() and mknodat() return 0.
Otherwise, it returns -1, the new file is not created, and
errno is set to indicate the error.ERRORS
The mknod() and mknodat() functions will fail if:
EACCES A component of the path prefix denies search permission, 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.
SunOS 5.11 Last change: 6 Jul 2010 3
System Calls mknod(2) 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 com-
ponent 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 becreated is located on a read-only file sys-
tem.The mknodat() function will fail if:
EACCES fd was not opened with O_SEARCH and the permis-
sions of the directory underlying fd do not permit directory searches. EBADF The path argument does not specify an absolutepath and the fd argument is neither AT_FDCWD nor a
valid file descriptor open for reading or search-
ing.SunOS 5.11 Last change: 6 Jul 2010 4
System Calls mknod(2)The mknod() and mknodat() functions may fail if:
ELOOP More than {SYMLOOP_MAX} symbolic 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 alength that exceeds {PATH_MAX}.
The mknodat() function may fail if:
ENOTDIR The path argument is not an absolute path and fdis neither AT_FDCWD nor a file descriptor associ-
ated with a directory.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 symlink(2). An endpoint for communication can be created using socket(3SOCKET).ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:SunOS 5.11 Last change: 6 Jul 2010 5
System Calls mknod(2)____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| MT-Level | Async-Signal-Safe |
|_____________________________|_____________________________|
| Standard | See standards(5). ||_____________________________|_____________________________|
SEE ALSO
chmod(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), standards(5)SunOS 5.11 Last change: 6 Jul 2010 6