fileno

FERROR(3)                  Linux Programmer's Manual                 FERROR(3)

NAME
       clearerr, feof, ferror, fileno - check and reset stream status

SYNOPSIS
       #include <stdio.h>

       void clearerr(FILE *stream);

       int feof(FILE *stream);

       int ferror(FILE *stream);

       int fileno(FILE *stream);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       fileno(): _POSIX_C_SOURCE

DESCRIPTION
       The function clearerr() clears the end-of-file and error indicators for
       the stream pointed to by stream.

       The function feof() tests the  end-of-file  indicator  for  the  stream
       pointed  to by stream, returning nonzero if it is set.  The end-of-file
       indicator can be cleared only by the function clearerr().

       The function ferror() tests the error indicator for the stream  pointed
       to  by stream, returning nonzero if it is set.  The error indicator can
       be reset only by the clearerr() function.

       The function fileno() examines the argument stream and returns the  in-
       teger file descriptor used to implement this stream.  The file descrip-
       tor is still owned by stream and  will  be  closed  when  fclose(3)  is
       called.  Duplicate the file descriptor with dup(2) before passing it to
       code that might close it.

       For nonlocking counterparts, see unlocked_stdio(3).

ERRORS
       These functions should not fail and do not set  the  external  variable
       errno.   (However,  in case fileno() detects that its argument is not a
       valid stream, it must return -1 and set errno to EBADF.)

ATTRIBUTES
       For an  explanation  of  the  terms  used  in  this  section,  see  at-
       tributes(7).

       +--------------------+---------------+---------+
       |Interface           | Attribute     | Value   |
       +--------------------+---------------+---------+
       |clearerr(), feof(), | Thread safety | MT-Safe |
       |ferror(), fileno()  |               |         |
       +--------------------+---------------+---------+
CONFORMING TO
       The  functions  clearerr(),  feof(),  and ferror() conform to C89, C99,
       POSIX.1-2001, and POSIX.1-2008.

       The function fileno() conforms to POSIX.1-2001 and POSIX.1-2008.

SEE ALSO
       open(2), fdopen(3), stdio(3), unlocked_stdio(3)

COLOPHON
       This page is part of release 5.05 of the Linux  man-pages  project.   A
       description  of  the project, information about reporting bugs, and the
       latest    version    of    this    page,    can     be     found     at
       https://www.kernel.org/doc/man-pages/.

                                  2019-03-06                         FERROR(3)