• 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
  
  
  

• DESCRIPTION
  
  The system call
  mknod ()
  creates a file system 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 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
  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 file system 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) .)
  

  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 file system containing
  pathname
  does not support the type of node requested.
  

  EROFS

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

• 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 function 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 3.19 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/.
  

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