stdio/FreeBSD/fflush.3

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  32 .\"     @(#)fflush.3    8.1 (Berkeley) 6/4/93
  33 .\" $FreeBSD: src/lib/libc/stdio/fflush.3,v 1.11 2007/01/09 00:28:06 imp Exp $
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  35 .Dd June 4, 1993
  36 .Dt FFLUSH 3
  37 .Os
  38 .Sh NAME
  39 .Nm fflush ,
  40 .Nm fpurge
  41 .Nd flush a stream
  42 .Sh LIBRARY
  43 .Lb libc
  44 .Sh SYNOPSIS
  45 .In stdio.h
  46 .Ft int
  47 .Fn fflush "FILE *stream"
  48 .Ft int
  49 .Fn fpurge "FILE *stream"
  50 .Sh DESCRIPTION
  51 The function
  52 .Fn fflush
  53 forces a write of all buffered data for the given output or update
  54 .Fa stream
  55 via the stream's underlying write function.
  56 The open status of the stream is unaffected.
  57 .Pp
  58 If the
  59 .Fa stream
  60 argument is
  61 .Dv NULL ,
  62 .Fn fflush
  63 flushes
  64 .Em all
  65 open output streams.
  66 .Pp
  67 The function
  68 .Fn fpurge
  69 erases any input or output buffered in the given
  70 .Fa stream .
  71 For output streams this discards any unwritten output.
  72 For input streams this discards any input read from the underlying object
  73 but not yet obtained via
  74 .Xr getc 3 ;
  75 this includes any text pushed back via
  76 .Xr ungetc 3 .
  77 .Sh RETURN VALUES
  78 Upon successful completion 0 is returned.
  79 Otherwise,
  80 .Dv EOF
  81 is returned and the global variable
  82 .Va errno
  83 is set to indicate the error.
  84 .Sh ERRORS
  85 .Bl -tag -width Er
  86 .It Bq Er EBADF
  87 The
  88 .Fa stream
  89 argument
  90 is not an open stream, or, in the case of
  91 .Fn fflush ,
  92 not a stream open for writing.
  93 .El
  94 .Pp
  95 The function
  96 .Fn fflush
  97 may also fail and set
  98 .Va errno
  99 for any of the errors specified for the routine
 100 .Xr write 2 .
 101 .Sh SEE ALSO
 102 .Xr write 2 ,
 103 .Xr fclose 3 ,
 104 .Xr fopen 3 ,
 105 .Xr setbuf 3
 106 .Sh STANDARDS
 107 The
 108 .Fn fflush
 109 function
 110 conforms to
 111 .St -isoC .