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NAME    [Toc]    [Back]

       mknod - create a special or ordinary file

SYNOPSIS    [Toc]    [Back]

       #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    [Toc]    [Back]

       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

       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

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

       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    [Toc]    [Back]

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

ERRORS    [Toc]    [Back]

       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

       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    [Toc]    [Back]
	      pathname was too long.

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

       ENOTDIR    [Toc]    [Back]
	      A  component  used as a directory in pathname is not, in fact, a

       ENOMEM Insufficient kernel memory was available.

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

       ELOOP  Too many symbolic links were encountered in resolving  pathname.

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

CONFORMING TO    [Toc]    [Back]

       SVr4  (but  the	call  requires	privilege  and	is thus not in POSIX),
       4.4BSD.	The Linux version differs from the SVr4  version  in  that  it
       does not require root permission to create pipes, also in that no EMULTIHOP,
 ENOLINK, or EINTR error is documented.

NOTES    [Toc]    [Back]

       The Austin draft 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  or	socket
       files,  and  cannot  be used to create normal files by users other than
       the superuser.  One should make directories with mkdir, and FIFOs  with

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

SEE ALSO    [Toc]    [Back]

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

Linux 1.0			  1994-03-29			      MKNOD(2)
[ Back ]
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