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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 file system node (file,  device  spe-
       cial  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), char-
       acter 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 file system is mounted with BSD group semantics, the new
       node will inherit the group ownership from its parent directory; other-
       wise 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 path-
              name did not allow search permission.   (See  also  path_resolu-
              tion(7).)
       EDQUOT The user's quota of disk blocks or inodes on the file system 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  dan-
              gling 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 behav-
       ior of mknod() is unspecified."  However, nowadays one should never use
       mknod()  for  this  purpose; one should use mkfifo(3), a function espe-
       cially 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 3.53 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)