MKNOD(2)

NAME
mknod - create a directory

SYNOPSIS
#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);

DESCRIPTION
mknod attempts to create a filesystem node (file, device special file or named pipe) named pathname, specified by mode and dev. mode 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 should be one of S_IFREG, S_IFCHR, S_IFBLK and S_IFIFO to specify a normal file (which will be created empty), character special file, block special file or FIFO (named pipe), respectively, or zero, which will create a normal file. 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. The newly created node will be owned by the effective uid 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 gid of the process.

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

ERRORS

EPERM
    mode requested creation of something other than a FIFO (named pipe), and the caller is not the superuser; also returned if the filesystem containing pathname does not support the type of node requested. EINVAL mode requested creation of something other than a normal file, device special file or FIFO. EEXIST pathname already exists.

EFAULT
    pathname points outside your accessible address space.

EACCES
    The parent directory does not allow write permission to the process, or one of the directories in pathname did not allow search (execute) permission.

ENAMETOOLONG
    pathname was too long.

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

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

ENOMEM
    Insufficient kernel memory was available.

EROFS
    pathname refers to a file on a read-only filesystem and write access was requested.

ELOOP
    pathname contains a reference to a circular symbolic link, ie a symbolic link whose expansion contains a reference to itself.

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

CONFORMING TO

BUGS
In some older versions of Linux (for example, 0.99pl7) all the normal filesystems sometime allow the creation of two files in the same directory with the same name. This occurs only rarely and only on a heavily loaded system. It is believed that this bug was fixed in the Minix filesystem in Linux 0.99pl8 pre-release; and it is hoped that it was fixed in the other filesystems shortly afterwards. mknod cannot be used to create directories or socket files, and cannot be used to create normal files by users other than the superuser. There are many infelicities in the protocol underlying NFS.

SEE ALSO
read(2), write(2), fcntl(2), close(2), unlink(2), open(2), mkdir(2), stat(2), umask(2), mount(2), socket(2), socket(2), fopen(3).