mknod - 創建一個特殊的文件或普通文件

內容簡介

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

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

描述

The system call  mknod () creates a filesystem node (file, device special file or named pipe) named  pathname , with attributes specified by  mode  and  dev .

The mode argument specifies both the permissions to use and the type of node to be created. It should be a combination (using bitwise OR) of one of the file types listed below and the permissions for the new node.

The permissions are modified by the process’s umask in the usual way: the permissions of the created node are (mode & ~umask).

The file type must be one of S_IFREG, S_IFCHR, S_IFBLK, S_IFIFO or S_IFSOCK to specify a normal file (which will be created empty), character special file, block special file, FIFO (named pipe), or Unix domain socket, respectively. (Zero file type is equivalent to type S_IFREG.)

If the file type is S_IFCHR or S_IFBLK then dev specifies the major and minor numbers of the newly created device special file; otherwise it is ignored.

If pathname already exists, or is a symbolic link, this call fails with an EEXIST error.

The newly created node will be owned by the effective user ID of the process. If the directory containing the node has the set-group-ID bit set, or if the filesystem is mounted with BSD group semantics, the new node will inherit the group ownership from its parent directory; otherwise it will be owned by the effective group ID of the process.

返回值

mknod () returns zero on success, or -1 if an error occurred (in which case,  errno  is set appropriately).

錯誤

標籤

描述

EACCES

The parent directory does not allow write permission to the process, or one of the directories in the path prefix of pathnamedid not allow search permission. (See also path_resolution(2).)

EEXIST

pathname already exists.

EFAULT

pathname points outside your accessible address space.

EINVAL

mode requested creation of something other than a normal file, device special file, FIFO or socket.

ELOOP

Too many symbolic links were encountered in resolvingpathname.

ENAMETOOLONG

 

pathname was too long.

ENOENT

A directory component in pathname does not exist or is a dangling symbolic link.

ENOMEM

Insufficient kernel memory was available.

ENOSPC

The device containing pathname has no room for the new node.

ENOTDIR

 

A component used as a directory in pathname is not, in fact, a directory.

EPERM

mode requested creation of something other than a regular file, FIFO (named pipe), or Unix domain socket, and the caller is not privileged (Linux: does not have the CAP_MKNOD capability); also returned if the filesystem containing pathname does not support the type of node requested.

EROFS

pathname refers to a file on a read-only filesystem.

遵循於

SVr4, 4.4BSD, POSIX.1-2001 (but see below).

注意

POSIX.1-2001 says: "The only portable use of  mknod () is to create a FIFO-special file. If mode  is not S_IFIFO or  dev  is not 0, the behavior of  mknod () is unspecified."

Under Linux, this call cannot be used to create directories. One should make directories with mkdir(2), and FIFOs with mkfifo(2).

There are many infelicities in the protocol underlying NFS. Some of these affect mknod().

另請參閱

• fcntl (2)

• mkdir (2)

• mknodat (2)

• mount (2)

• path_resolution (2)

• socket (2)

• stat (2)

• umask (2)

• unlink (2)