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4 .\" This code is derived from software contributed to Berkeley by
5 .\" Chris Torek and the American National Standards Committee X3,
6 .\" on Information Processing Systems.
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36 .\" @(#)fflush.3 8.1 (Berkeley) 6/4/93
37 .\" $FreeBSD: src/lib/libc/stdio/fflush.3,v 1.4.2.4 2001/12/14 18:33:57 ru Exp $
38 .\" $DragonFly: src/lib/libc/stdio/fflush.3,v 1.3 2004/06/08 00:29:47 hmp Exp $
39 .\"
40 .Dd June 4, 1993
41 .Dt FFLUSH 3
42 .Os
43 .Sh NAME
44 .Nm fflush ,
45 .Nm fpurge
46 .Nd flush a stream
47 .Sh LIBRARY
48 .Lb libc
49 .Sh SYNOPSIS
50 .In stdio.h
51 .Ft int
52 .Fn fflush "FILE *stream"
53 .Ft int
54 .Fn fpurge "FILE *stream"
55 .Sh DESCRIPTION
56 The function
57 .Fn fflush
58 forces a write of all buffered data for the given output or update
59 .Fa stream
60 via the stream's underlying write function.
61 The open status of the stream is unaffected.
62 .Pp
63 If the
64 .Fa stream
65 argument is
66 .Dv NULL ,
67 .Fn fflush
68 flushes
69 .Em all
70 open output streams.
71 .Pp
72 The function
73 .Fn fpurge
74 erases any input or output buffered in the given
75 .Fa stream .
76 For output streams this discards any unwritten output.
77 For input streams this discards any input read from the underlying object
78 but not yet obtained via
79 .Xr getc 3 ;
80 this includes any text pushed back via
81 .Xr ungetc 3 .
82 .Sh RETURN VALUES
83 Upon successful completion 0 is returned.
84 Otherwise,
85 .Dv EOF
86 is returned and the global variable
87 .Va errno
88 is set to indicate the error.
89 .Sh ERRORS
90 .Bl -tag -width Er
91 .It Bq Er EBADF
92 The
93 .Fa stream
94 argument
95 is not an open stream, or, in the case of
96 .Fn fflush ,
97 not a stream open for writing.
98 .El
99 .Pp
100 The function
101 .Fn fflush
102 may also fail and set
103 .Va errno
104 for any of the errors specified for the routine
105 .Xr write 2 .
106 .Sh SEE ALSO
107 .Xr write 2 ,
108 .Xr fclose 3 ,
109 .Xr fopen 3 ,
110 .Xr setbuf 3
111 .Sh STANDARDS
112 The
113 .Fn fflush
114 function
115 conforms to
116 .St -isoC .