NAME

mknod - make a directory, or a special or ordinary file

SYNOPSIS

#include <sys/types.h>
#include <osfcn.h>
#include <sys/stat.h>

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

DESCRIPTION

mknod 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
        S_IFNAM   name special file

     The file access permissions are specified  in  mode  by  the
     0007777 bits, and may be constructed by an OR of the follow-
     ing 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/record locking if # is 6, 4, 2, or 0
S_ISVTX   01000   Save text image  after execution.
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 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 the supplementary group IDs, the S_ISGID bit is cleared.

Values of mode other than those above are undefined and should not be used. 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)]. For block and character special files, dev is the special file's device number. For name special files, dev is the file type of the name file, either a XENIX shared data file or a XENIX semaphore. Otherwise, dev is ignored. See mkdev(3C).

mknod may be invoked only by the privileged user for file types other than FIFO special.

mknod fails and creates no new file if one or more of the following are true:

EEXIST The named file exists.

EINVAL Invalid arg value.

EFAULT path points outside the allocated address space of the process.

ELOOP Too many symbolic links were encountered in translating path.

EMULTIHOP Components of path require hopping to multiple remote machines.

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.

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

ENOENT A component of the path prefix does not exist or is a null pathname.

EPERM The effective user ID of the process is not super-user.

EROFS The directory in which the file is to be created is located on a read-only file system.

ENOSPC No space is available.

EINTR A signal was caught during the mknod system call.

ENOLINK path points to a remote machine and the link to that machine is no longer active.

SEE ALSO

chmod(2), exec(2), umask(2), mkdev(3C), mkfifo(3C), stat(5).
fs(4) in the System Administrator's Reference Manual.
mkdir(1) in the User's Reference Manual.
creatsem(2), sdget(2) in the BSD/XENIX Compatibility Guide.

DIAGNOSTICS

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

NOTES

If mknod creates a device in a remote directory using Remote File Sharing, the major and minor device numbers are interpreted by the server.

Semaphore files should be created with the creatsem system call. Shared data files should be created with the sdget system call.