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Annotation of cci/usr/src/man/man3/fopen.3s, revision 1.1

1.1     ! root        1: .TH FOPEN 3S  "1 April 1981"
        !             2: .UC 4
        !             3: .SH NAME
        !             4: fopen, freopen, fdopen \- open a stream
        !             5: .SH SYNOPSIS
        !             6: .B #include <stdio.h>
        !             7: .PP
        !             8: .SM
        !             9: .B FILE
        !            10: .B *fopen(filename, type)
        !            11: .br
        !            12: .B char *filename, *type;
        !            13: .PP
        !            14: .SM
        !            15: .B FILE
        !            16: .B *freopen(filename, type, stream)
        !            17: .br
        !            18: .B char *filename, *type;
        !            19: .br
        !            20: .SM
        !            21: .B FILE
        !            22: .B *stream;
        !            23: .PP
        !            24: .SM
        !            25: .B FILE
        !            26: .B *fdopen(fildes, type)
        !            27: .br
        !            28: .B char *type;
        !            29: .SH DESCRIPTION
        !            30: .I Fopen
        !            31: opens the file named by
        !            32: .I filename
        !            33: and associates a stream with it.
        !            34: .I Fopen
        !            35: returns a pointer to be used to identify the stream in subsequent operations.
        !            36: .PP
        !            37: .I Type
        !            38: is a character string having one of the following values:
        !            39: .TP 5
        !            40: "r"
        !            41: open for reading
        !            42: .ns
        !            43: .TP 5
        !            44: "w"
        !            45: create for writing
        !            46: .ns
        !            47: .TP 5
        !            48: "a"
        !            49: append: open for writing at end of file, or create for writing
        !            50: .PP
        !            51: In addition, each
        !            52: .I type
        !            53: may be followed by a '+' to have the file opened for reading and writing.
        !            54: "r+" positions the stream at the beginning of the file, "w+" creates
        !            55: or truncates it, and "a+" positions it at the end.  Both reads and writes
        !            56: may be used on read/write streams, with the limitation that an
        !            57: .I fseek, rewind,
        !            58: or reading an end-of-file must be used between a read and a write or vice-versa.
        !            59: .PP
        !            60: .I Freopen
        !            61: substitutes the named file in place of the open
        !            62: .IR stream .
        !            63: It returns the original value of
        !            64: .IR stream .
        !            65: The original stream is closed.
        !            66: .PP
        !            67: .I Freopen
        !            68: is typically used to attach the preopened constant names,
        !            69: .B stdin, stdout, stderr,
        !            70: to specified files.
        !            71: .PP
        !            72: .I Fdopen
        !            73: associates a stream with a file descriptor obtained from
        !            74: .I open, dup, creat,
        !            75: or
        !            76: .IR pipe (2).
        !            77: The
        !            78: .I type
        !            79: of the stream must agree with the mode of the open file.
        !            80: .SH "SEE ALSO"
        !            81: open(2),
        !            82: fclose(3)
        !            83: .SH DIAGNOSTICS
        !            84: .I Fopen
        !            85: and 
        !            86: .I freopen
        !            87: return the pointer
        !            88: .SM
        !            89: .B NULL
        !            90: if
        !            91: .I filename
        !            92: cannot be accessed.
        !            93: .SH BUGS
        !            94: .I Fdopen
        !            95: is not portable to systems other than UNIX.
        !            96: .PP
        !            97: The read/write 
        !            98: .I types
        !            99: do not exist on all systems.  Those systems without
        !           100: read/write modes will probably treat the 
        !           101: .I type
        !           102: as if the '+' was not present.  These are unreliable in any event.

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