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32 .\" @(#)fopen.3 8.1 (Berkeley) 6/4/93
42 .Nd stream open functions
48 .Fn fopen "const char * restrict path" "const char * restrict mode"
50 .Fn fdopen "int fildes" "const char *mode"
52 .Fn freopen "const char *path" "const char *mode" "FILE *stream"
54 .Fn fmemopen "void * restrict buf" "size_t size" "const char * restrict mode"
59 opens the file whose name is the string pointed to by
61 and associates a stream with it.
65 points to a string beginning with one of the following letters:
66 .Bl -tag -width indent
69 The stream is positioned at the beginning of the file.
70 Fail if the file does not exist.
73 The stream is positioned at the beginning of the file.
74 Truncate the file to zero length if it exists or create the file if it does not exist.
77 The stream is positioned at the end of the file.
78 Subsequent writes to the file will always end up at the then current
79 end of file, irrespective of any intervening
82 Create the file if it does not exist.
92 opens the file for both reading and writing.
101 call to fail if the file already exists.
109 flag on the underlying file descriptor.
113 string can also include the letter
118 This is strictly for compatibility with
120 and has effect only for
126 Any created files will have mode
139 as modified by the process'
143 Reads and writes may be intermixed on read/write streams in any order,
144 and do not require an intermediate seek as in previous versions of
146 This is not portable to other systems, however;
151 a file positioning function intervene between output and input, unless
152 an input operation encounters end-of-file.
156 function associates a stream with the existing file descriptor,
159 of the stream must be compatible with the mode of the file descriptor.
162 mode option is ignored.
165 mode option is present, the
167 flag is set, otherwise it remains unchanged.
168 When the stream is closed via
176 opens the file whose name is the string pointed to by
178 and associates the stream pointed to by
181 The original stream (if it exists) is closed.
184 argument is used just as in the
193 attempts to re-open the file associated with
196 The new mode must be compatible with the mode that the stream was originally
198 Streams open for reading can only be re-opened for reading,
199 streams open for writing can only be re-opened for writing,
200 and streams open for reading and writing can be re-opened in any mode.
203 mode option is not meaningful in this context.
205 The primary use of the
208 is to change the file associated with a
210 .Dv ( stderr , stdin ,
217 associates the buffer given by the
221 arguments with a stream.
224 argument is either a null pointer or point to a buffer that
228 If a null pointer is specified as the
235 This buffer is automatically freed when the stream is closed.
236 Buffers can be opened in text-mode (default) or binary-mode
239 is present in the second or third position of the
242 Buffers opened in text-mode make sure that writes are terminated with a
244 byte, if the last write hasn't filled up the whole buffer.
245 Buffers opened in binary-mode never append a
249 Upon successful completion
260 is returned and the global variable
262 is set to indicate the error.
285 may also fail and set
287 for any of the errors specified for the routine
293 may also fail and set
295 for any of the errors specified for the routine
301 may also fail and set
303 for any of the errors specified for the routine
309 may also fail and set
311 for any of the errors specified for the routines
320 may also fail and set
339 with the exception of the
341 mode option which conforms to
350 mode option does not conform to any standard
351 but is also supported by glibc.
359 mode does not conform to any standard
360 but is also supported by glibc.