119 lines
2.5 KiB
Groff
119 lines
2.5 KiB
Groff
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FOPEN(3) Minix Programmer's Manual FOPEN(3)
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NAME
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fopen, freopen, fdopen - open a stream
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SYNOPSIS
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#include <stdio.h>
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FILE *fopen(const char *filename, const char *type)
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FILE *freopen(const char *filename, const char *type, FILE *stream)
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FILE *fdopen(int fildes, const char *type)
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DESCRIPTION
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Fopen opens the file named by filename and associates a stream with it.
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Fopen returns a pointer to be used to identify the stream in subsequent
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operations.
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Type is a character string having one of the following values:
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"r" open for reading
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"w" create for writing
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"a" append: open for writing at end of file, or create for writing
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In addition, each type may be followed by a "+" to have the file opened
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for reading and writing. "r+" positions the stream at the beginning of
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the file, "w+" creates or truncates it, and "a+" positions it at the end.
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Both reads and writes may be used on read/write streams, with the
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limitation that an fseek, rewind, or reading an end-of-file must be used
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between a read and a write or vice-versa.
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Freopen substitutes the named file in place of the open stream. It
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returns the original value of stream. The original stream is closed.
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Freopen is typically used to attach the preopened constant names, stdin,
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stdout, stderr, to specified files.
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Fdopen associates a stream with a file descriptor obtained from open,
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dup, creat, or pipe(2). The type of the stream must agree with the mode
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of the open file.
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SEE ALSO
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open(2), fclose(3).
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DIAGNOSTICS
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Fopen and freopen return the pointer NULL if filename cannot be accessed,
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if too many files are already open, or if other resources needed cannot
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be allocated.
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4BSD May 27, 1986 1
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FOPEN(3) Minix Programmer's Manual FOPEN(3)
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BUGS
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Fdopen is not portable to systems other than UNIX.
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The read/write types do not exist on all systems. Those systems without
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read/write modes will probably treat the type as if the "+" was not
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present. These are unreliable in any event.
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4BSD May 27, 1986 2
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