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32 .\" @(#)fopen.3 8.1 (Berkeley) 6/4/93
43 .Nd stream open functions
49 .Fn fopen "const char * restrict path" "const char * restrict mode"
51 .Fn fdopen "int fildes" "const char *mode"
53 .Fn freopen "const char *path" "const char *mode" "FILE *stream"
55 .Fn fmemopen "void *restrict *buf" "size_t size" "const char * restrict mode"
60 opens the file whose name is the string pointed to by
62 and associates a stream with it.
66 points to a string beginning with one of the following letters:
67 .Bl -tag -width indent
70 The stream is positioned at the beginning of the file.
71 Fail if the file does not exist.
74 The stream is positioned at the beginning of the file.
75 Create the file if it does not exist.
78 The stream is positioned at the end of the file.
79 Subsequent writes to the file will always end up at the then current
80 end of file, irrespective of any intervening
83 Create the file if it does not exist.
93 opens the file for both reading and writing.
102 call to fail if the file already exists.
106 string can also include the letter
111 This is strictly for compatibility with
113 and has effect only for
115 ; otherwise the ``b'' is ignored.
117 Any created files will have mode
130 as modified by the process'
134 Reads and writes may be intermixed on read/write streams in any order,
135 and do not require an intermediate seek as in previous versions of
137 This is not portable to other systems, however;
140 a file positioning function intervene between output and input, unless
141 an input operation encounters end-of-file.
145 function associates a stream with the existing file descriptor,
148 of the stream must be compatible with the mode of the file descriptor.
151 mode option is ignored.
152 When the stream is closed via
160 opens the file whose name is the string pointed to by
162 and associates the stream pointed to by
165 The original stream (if it exists) is closed.
168 argument is used just as in the
177 attempts to re-open the file associated with
180 The new mode must be compatible with the mode that the stream was originally
182 Streams open for reading can only be re-opened for reading,
183 streams open for writing can only be re-opened for writing,
184 and streams open for reading and writing can be re-opened in any mode.
187 mode option is not meaningful in this context.
189 The primary use of the
192 is to change the file associated with a
194 .Dv ( stderr , stdin ,
201 associates the buffer given by the
205 arguments with a stream.
208 argument is either a null pointer or point to a buffer that
212 If a null pointer is specified as the
218 bytes of memory. This buffer is automatically freed when the
219 stream is closed. Buffers can be opened in text-mode (default) or binary-mode
220 (if ``b'' is present in the second or third position of the
222 argument). Buffers opened in text-mode make sure that writes are terminated with
223 a NULL byte, if the last write hasn't filled up the whole buffer. Buffers
224 opened in binary-mode never append a NULL byte.
226 Upon successful completion
236 is returned and the global variable
238 is set to indicate the error.
261 may also fail and set
263 for any of the errors specified for the routine
269 may also fail and set
271 for any of the errors specified for the routine
277 may also fail and set
279 for any of the errors specified for the routine
285 may also fail and set
287 for any of the errors specified for the routines
306 with the exception of the
308 mode option which conforms to
320 The ``b'' mode does not conform to any standard
321 but is also supported by glibc.