mknod


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 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).)
              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 3.23 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                             2008-12-01                          MKNOD(2)
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