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Linux 2.6 - man page for mknod (linux section 2)

MKNOD(2)			    Linux Programmer's Manual				 MKNOD(2)

NAME
       mknod - create a special or ordinary file

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);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       mknod():
	   _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
	   _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED

DESCRIPTION
       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 cre-
       ated.  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
       regular	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 (makedev(3) may be useful to  build  the  value  for
       dev); 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.

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

ERRORS
       EACCES The  parent directory does not allow write permission to the process, or one of the
	      directories in the path prefix of pathname did not allow search  permission.   (See
	      also path_resolution(7).)

       EDQUOT The user's quota of disk blocks or inodes on the filesystem has been exhausted.

       EEXIST pathname already exists.	This includes the case where pathname is a symbolic link,
	      dangling or not.

       EFAULT pathname points outside your accessible address space.

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

       ELOOP  Too many symbolic links were encountered in resolving pathname.

       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.

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

NOTES
       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."  However,
       nowadays one should never use mknod() for this purpose; one should use mkfifo(3), a  func-
       tion especially defined for this purpose.

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

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

SEE ALSO
       chmod(2),  chown(2),  fcntl(2),	mkdir(2),  mknodat(2),	mount(2),   socket(2),	 stat(2),
       umask(2), unlink(2), makedev(3), mkfifo(3), path_resolution(7)

COLOPHON
       This  page  is  part of release 3.55 of the Linux man-pages project.  A description of the
       project,    and	  information	 about	  reporting    bugs,	can    be    found     at
       http://www.kernel.org/doc/man-pages/.

Linux					    2013-01-27					 MKNOD(2)


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