#include <sys/stat.h>int mknod(const char *path, mode_t mode, dev_t dev);
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:
The file access permissions are specified in mode by the 0007777 bits, and may be constructed by a bitwise OR operation 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/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 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.
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 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() returns 0. Otherwise, it returns -1, the new file is not created, and errno is set to indicate the error.
The mknod() function will fail if:
A component of the path prefix denies search permission, or write permission is denied on the parent directory.
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.
The named file exists.
The path argument points to an illegal address.
A signal was caught during the execution of the mknod() function.
An invalid argument exists.
An I/O error occurred while accessing the file system.
Too many symbolic links were encountered in translating path.
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.
A component of the path prefix specified by path does not name an existing directory or path is an empty string.
The path argument points to a remote machine and the link to that machine is no longer active.
The directory that would contain the new file cannot be extended or the file system is out of file allocation resources.
A component of the path prefix is not a directory.
The effective user of the calling process is not super-user.
The directory in which the file is to be created is located on a read-only file system.
The mknod() function may fail if:
Pathname resolution of a symbolic link produced an intermediate result whose length exceeds PATH_MAX.
Normally, applications should use the mkdir(2) routine to make a directory, since the function mknod() may not establish directory entries for the directory itself (.) and the parent directory (. .), and appropriate permissions are not required. Similarly, mkfifo(3C) should be used in place of mknod() in order to create FIFOs.
The mknod() function may be invoked only by a privileged user for file types other than FIFO special.