200 lines
5.3 KiB
Groff
200 lines
5.3 KiB
Groff
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.\" Copyright (c) 1980 Regents of the University of California.
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.\" All rights reserved. The Berkeley software License Agreement
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.\" specifies the terms and conditions for redistribution.
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.\"
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.\" @(#)stdio.3s 6.2 (Berkeley) 5/13/86
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.\"
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.TH STDIO 3 "May 13, 1986"
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.UC 4
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.SH NAME
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stdio \- standard buffered input/output package
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.SH SYNOPSIS
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.nf
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.ft B
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#include <stdio.h>
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FILE *stdin;
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FILE *stdout;
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FILE *stderr;
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.ft R
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.fi
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.SH DESCRIPTION
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The functions in the standard I/O library constitute a user-level buffering
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scheme. The in-line macros
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.B getc
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and
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.BR putc (3)
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handle characters quickly. The higher level routines
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.BR gets ,
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.BR fgets ,
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.BR scanf ,
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.BR fscanf ,
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.BR fread ,
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.BR puts ,
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.BR fputs ,
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.BR printf ,
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.BR fprintf ,
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.BR fwrite
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all use
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.B getc
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and
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.BR putc ;
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they can be freely intermixed.
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.PP
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A file with associated buffering is called a
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.IR stream ,
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and is declared to be a pointer to a defined type
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.SM
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.BR FILE .
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.BR Fopen (3)
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creates certain descriptive data for a stream
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and returns a pointer to designate the stream in all further transactions.
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There are three normally open streams with constant pointers declared in
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the include file and associated with the standard open files:
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.TP 10n
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.B stdin
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standard input file
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.br
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.ns
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.TP
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.B stdout
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standard output file
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.br
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.ns
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.TP
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.B stderr
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standard error file
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.PP
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A constant `pointer'
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.SM
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.B NULL
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(0)
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designates no stream at all.
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.PP
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An integer constant
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.SM
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.B EOF
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(\-1) is returned upon end of file or error by integer functions that
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deal with streams.
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.PP
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Any routine that uses the standard input/output package
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must include the header file
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.RI < stdio.h >
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of pertinent macro definitions.
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The functions and constants mentioned in the standard I/O manual pages
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are declared in the include file and need no further declaration.
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The constants, and the following `functions' are
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implemented as macros; redeclaration of these names is perilous:
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.BR clearerr ,
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.BR getc ,
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.BR getchar ,
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.BR putc ,
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.BR putchar ,
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.BR feof ,
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.BR ferror ,
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.BR fileno .
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.SH "SEE ALSO"
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.BR open (2),
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.BR close (2),
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.BR read (2),
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.BR write (2),
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.BR fclose (3),
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.BR ferror (3),
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.BR fopen (3),
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.BR fread (3),
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.BR fseek (3),
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.BR getc (3),
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.BR gets (3),
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.BR printf (3),
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.BR putc (3),
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.BR puts (3),
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.BR scanf (3),
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.BR setbuf (3),
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.BR ungetc (3).
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.SH DIAGNOSTICS
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The value
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.SM
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.B EOF
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is returned uniformly to indicate that a
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.SM
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.B FILE
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pointer has not been initialized with
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.BR fopen ,
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input (output) has been attempted on an output (input) stream, or a
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.SM
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.B FILE
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pointer designates corrupt or otherwise unintelligible
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.SM
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.B FILE
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data.
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.PP
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For purposes of efficiency, this implementation of the standard library
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has been changed to line buffer output to a terminal by default and attempts
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to do this transparently by flushing the output whenever a
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.BR read (2)
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from the standard input is necessary. This is almost always transparent,
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but may cause confusion or malfunctioning of programs which use
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standard i/o routines but use
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.BR read (2)
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themselves to read from the standard input.
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.PP
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In cases where a large amount of computation is done after printing
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part of a line on an output terminal, it is necessary to
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.BR fflush (3)
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the standard output before going off and computing so that the output
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will appear.
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.SH BUGS
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The standard buffered functions do not interact well with certain other
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library and system functions, especially \fBfork\fP and \fBabort\fP.
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.SH "LIST OF FUNCTIONS"
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.sp 2
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.nf
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.ta \w'setlinebuf'u+2n +\w'setbuf(3)'u+10n
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\fBName\fP \fBAppears on Page\fP \fBDescription\fP
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.ta \w'setlinebuf'u+4n +\w'setbuf(3)'u+4n
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.sp 5p
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clearerr ferror(3) stream status inquiries
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fclose fclose(3) close or flush a stream
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fdopen fopen(3) open a stream
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feof ferror(3) stream status inquiries
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ferror ferror(3) stream status inquiries
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fflush fclose(3) close or flush a stream
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fgetc getc(3) get character or word from stream
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fgets gets(3) get a string from a stream
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fileno ferror(3) stream status inquiries
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fopen fopen(3) open a stream
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fprintf printf(3) formatted output conversion
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fputc putc(3) put character or word on a stream
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fputs puts(3) put a string on a stream
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fread fread(3) buffered binary input/output
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freopen fopen(3) open a stream
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fscanf scanf(3) formatted input conversion
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fseek fseek(3) reposition a stream
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ftell fseek(3) reposition a stream
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fwrite fread(3) buffered binary input/output
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getc getc(3) get character or word from stream
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getchar getc(3) get character or word from stream
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gets gets(3) get a string from a stream
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getw getc(3) get character or word from stream
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printf printf(3) formatted output conversion
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putc putc(3) put character or word on a stream
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putchar putc(3) put character or word on a stream
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puts puts(3) put a string on a stream
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putw putc(3) put character or word on a stream
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rewind fseek(3) reposition a stream
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scanf scanf(3) formatted input conversion
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setbuf setbuf(3) assign buffering to a stream
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setvbuf setbuf(3) assign buffering to a stream
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snprintf printf(3) formatted output conversion
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sprintf printf(3) formatted output conversion
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sscanf scanf(3) formatted input conversion
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ungetc ungetc(3) push character back into input stream
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vfprintf printf(3) formatted output conversion
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vfscanf scanf(3) formatted input conversion
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vprintf printf(3) formatted output conversion
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vscanf scanf(3) formatted input conversion
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vsnprintf printf(3) formatted output conversion
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vsprintf printf(3) formatted output conversion
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vsscanf scanf(3) formatted input conversion
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.fi
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