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fileno(3)
NAME
  fileno - Maps a stream pointer to a file descriptor

LIBRARY
  Standard C Library (libc.so, libc.a)

SYNOPSIS
  #include <stdio.h>

  int fileno(
	  FILE *stream);

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  fileno():  XPG4, XPG4-UNIX

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  stream    Specifies the input stream.

DESCRIPTION
  The fileno() function returns the integer file descriptor associated with
  the stream pointed to by stream.

NOTES
  [Digital]  The fileno() function may be a macro (depending on the compile-
  time definitions used in the source).	 Consequently, you cannot use this
  interface where a function is necessary; for example, a subroutine pointer
  cannot point to the interface.

RETURN VALUES
  Upon successful completion, the fileno() macro returns the integer value of
  the file descriptor associated with the stream parameter.  Otherwise, the
  value -1 is returned.

RELATED INFORMATION
  Functions: clearerr(3), fdopen(3), feof(3), ferror(3), fopen(3), open(2)

  Standards: standards(5)