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32 .\" @(#)fopen.3 8.1 (Berkeley) 6/4/93
33 .\" $FreeBSD: src/lib/libc/stdio/fopen.3,v 1.20 2007/01/09 00:28:06 imp Exp $
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 * restrict path" "const char * restrict mode" "FILE * restrict stream"
57 opens the file whose name is the string pointed to by
59 and associates a stream with it.
63 points to a string beginning with one of the following
64 sequences (Additional characters may follow these sequences.):
65 .Bl -tag -width indent
67 Open file for reading.
68 The stream is positioned at the beginning of the file.
70 Open file for writing.
71 Creates the file if it does not already exist,
72 truncates the file if it does.
75 Creates the file if it does not already exist.
76 Seeks to end of the file.
77 Subsequent writes to the file will always end up at the then current
78 end of file, irrespective of any intervening
83 Additional flags may modify the primary mode as follows:
84 .Bl -tag -width indent
86 The file will be opened for both reading and writing.
87 For example 'r+' or 'w+'.
89 The open will fail if the file already exists (C11).
92 Close-on-exec. The underlying descriptor will automatically be closed on
93 any exec() (glibc compatibility).
95 Binary mode. On UNIX systems file reading and writing is always in binary
96 mode so this flag has no effect.
101 string can also include the letter ``b'' either as a third character or
102 as a character between the characters in any of the two-character strings
104 This is strictly for compatibility with
106 and has no effect; the ``b'' is ignored.
108 Any created files will have mode
121 as modified by the process'
125 Reads and writes may be intermixed on read/write streams in any order,
126 and do not require an intermediate seek as in previous versions of
128 This is not portable to other systems, however;
131 a file positioning function intervene between output and input, unless
132 an input operation encounters end-of-file.
136 function associates a stream with the existing file descriptor,
139 of the stream must be compatible with the mode of the file descriptor.
140 When the stream is closed via
148 opens the file whose name is the string pointed to by
150 and associates the stream pointed to by
153 The original stream (if it exists) is closed.
156 argument is used just as in the
165 attempts to re-open the file associated with
168 The new mode must be compatible with the mode that the stream was originally
170 .Bl -bullet -offset indent
172 Streams originally opened with mode
174 can only be reopened with that same mode.
176 Streams originally opened with mode
178 can be reopened with the same mode, or mode
181 Streams originally opened with mode
183 can be reopened with the same mode, or mode
186 Streams originally opened with mode
191 can be reopened with any mode.
194 The primary use of the
197 is to change the file associated with a
199 .Dv ( stderr , stdin ,
203 Upon successful completion
213 is returned and the global variable
215 is set to indicate the error.
236 may also fail and set
238 for any of the errors specified for the routine
244 may also fail and set
246 for any of the errors specified for the routine
252 may also fail and set
254 for any of the errors specified for the routine
260 may also fail and set
262 for any of the errors specified for the routines