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NAME

       mknod - make a directory, a special file, or a regular file

SYNOPSIS

       #include <sys/stat.h>

       int mknod(const char *path, mode_t mode, dev_t dev);

DESCRIPTION

       The  mknod()  function shall create a new file named by the pathname to
       which the argument path points.

       The file type for path  is  OR'ed  into  the  mode  argument,  and  the
       application shall select one of the following symbolic constants:

                     Name      Description
                     S_IFIFO   FIFO-special
                     S_IFCHR   Character-special (non-portable)
                     S_IFDIR   Directory (non-portable)
                     S_IFBLK   Block-special (non-portable)
                     S_IFREG   Regular (non-portable)

       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.

       The  permissions for the new file are OR'ed into the mode argument, and
       may  be  selected  from  any  combination  of  the  following  symbolic
       constants:

                Name     Description
                S_ISUID  Set user ID on execution.
                S_ISGID  Set group ID on execution.
                S_IRWXU  Read, write, or execute (search) by owner.
                S_IRUSR  Read by owner.
                S_IWUSR  Write by owner.
                S_IXUSR  Execute (search) by owner.
                S_IRWXG  Read, write, or execute (search) by group.
                S_IRGRP  Read by group.
                S_IWGRP  Write by group.
                S_IXGRP  Execute (search) by group.
                S_IRWXO  Read, write, or execute (search) by others.
                S_IROTH  Read by others.
                S_IWOTH  Write by others.
                S_IXOTH  Execute (search) by others.
                S_ISVTX  On directories, restricted deletion flag.

       The  user  ID of the file shall be initialized to the effective user ID
       of the process. The group ID of the file shall be initialized to either
       the  effective  group  ID  of the process or the group ID of the parent
       directory. Implementations shall provide a way to initialize the file's
       group  ID to the group ID of the parent directory. Implementations may,
       but need not, provide an implementation-defined way to  initialize  the
       file's  group  ID to the effective group ID of the calling process. The
       owner, group, and other permission bits of mode shall  be  modified  by
       the  file mode creation mask of the process. The mknod() function shall
       clear each bit whose corresponding bit in the file mode  creation  mask
       of the process is set.

       If  path  names  a  symbolic  link, mknod() shall fail and set errno to
       [EEXIST].

       Upon successful completion, mknod() shall mark for update the st_atime,
       st_ctime,  and  st_mtime  fields  of  the  file. Also, the st_ctime and
       st_mtime fields of the directory that contains the new entry  shall  be
       marked for update.

       Only  a process with appropriate privileges may invoke mknod() for file
       types other than FIFO-special.

RETURN VALUE

       Upon successful completion, mknod() shall return 0. Otherwise, it shall
       return -1, the new file shall not be created, and errno shall be set to
       indicate the error.

ERRORS

       The mknod() function shall fail if:

       EACCES A component of the path  prefix  denies  search  permission,  or
              write permission is denied on the parent directory.

       EEXIST The named file exists.

       EINVAL An invalid argument exists.

       EIO    An I/O error occurred while accessing the file system.

       ELOOP  A loop exists in symbolic links encountered during resolution of
              the path argument.

       ENAMETOOLONG
              The length of  a  pathname  exceeds  {PATH_MAX}  or  a  pathname
              component is longer than {NAME_MAX}.

       ENOENT A  component  of the path prefix specified by path does not name
              an existing directory or path is an empty string.

       ENOSPC The directory that would contain the new file cannot be extended
              or the file system is out of file allocation resources.

       ENOTDIR
              A component of the path prefix is not a directory.

       EPERM  The  invoking  process  does not have appropriate privileges and
              the file type is not FIFO-special.

       EROFS  The directory in which the file is to be created is located on a
              read-only file system.

       The mknod() function may fail if:

       ELOOP  More  than  {SYMLOOP_MAX} symbolic links were encountered during
              resolution of the path argument.

       ENAMETOOLONG
              Pathname resolution of a symbolic link produced an  intermediate
              result whose length exceeds {PATH_MAX}.

       The following sections are informative.

EXAMPLES

   Creating a FIFO Special File
       The  following  example  shows  how to create a FIFO special file named
       /home/cnd/mod_done, with read/write permissions  for  owner,  and  with
       read permissions for group and others.

              #include <sys/types.h>
              #include <sys/stat.h>

              dev_t dev;
              int   status;
              ...
              status  = mknod("/home/cnd/mod_done", S_IFIFO | S_IWUSR |
                  S_IRUSR | S_IRGRP | S_IROTH, dev);

APPLICATION USAGE

       The  mkfifo()  function is preferred over this function for making FIFO
       special files.

RATIONALE

       The POSIX.1-1990 standard required that the group ID of a newly created
       file be set to the group ID of its parent directory or to the effective
       group  ID  of  the  creating  process.   FIPS   151-2   required   that
       implementations  provide a way to have the group ID be set to the group
       ID of the containing directory, but did  not  prohibit  implementations
       also  supporting a way to set the group ID to the effective group ID of
       the creating process. Conforming applications should not  assume  which
       group ID will be used. If it matters, an application can use chown() to
       set the group ID after the file is created,  or  determine  under  what
       conditions the implementation will set the desired group ID.

FUTURE DIRECTIONS

       None.

SEE ALSO

       chmod()  ,  creat()  ,  exec() , mkdir() , mkfifo() , open() , stat() ,
       umask()  ,  the  Base  Definitions  volume   of   IEEE Std 1003.1-2001,
       <sys/stat.h>

COPYRIGHT

       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE and
       The  Open Group Standard, the original IEEE and The Open Group Standard
       is the referee document. The original Standard can be  obtained  online
       at http://www.opengroup.org/unix/online.html .