1IO::Seekable(3pm)      Perl Programmers Reference Guide      IO::Seekable(3pm)
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NAME

6       IO::Seekable - supply seek based methods for I/O objects
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SYNOPSIS

9           use IO::Seekable;
10           package IO::Something;
11           @ISA = qw(IO::Seekable);
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DESCRIPTION

14       "IO::Seekable" does not have a constructor of its own as it is intended
15       to be inherited by other "IO::Handle" based objects. It provides
16       methods which allow seeking of the file descriptors.
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18       $io->getpos
19           Returns an opaque value that represents the current position of the
20           IO::File, or "undef" if this is not possible (eg an unseekable
21           stream such as a terminal, pipe or socket). If the fgetpos()
22           function is available in your C library it is used to implements
23           getpos, else perl emulates getpos using C's ftell() function.
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25       $io->setpos
26           Uses the value of a previous getpos call to return to a previously
27           visited position. Returns "0 but true" on success, "undef" on
28           failure.
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30       See perlfunc for complete descriptions of each of the following
31       supported "IO::Seekable" methods, which are just front ends for the
32       corresponding built-in functions:
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34       $io->seek ( POS, WHENCE )
35           Seek the IO::File to position POS, relative to WHENCE:
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37           WHENCE=0 (SEEK_SET)
38                   POS is absolute position. (Seek relative to the start of
39                   the file)
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41           WHENCE=1 (SEEK_CUR)
42                   POS is an offset from the current position. (Seek relative
43                   to current)
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45           WHENCE=2 (SEEK_END)
46                   POS is an offset from the end of the file. (Seek relative
47                   to end)
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49           The SEEK_* constants can be imported from the "Fcntl" module if you
50           don't wish to use the numbers 0 1 or 2 in your code.
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52           Returns 1 upon success, 0 otherwise.
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54       $io->sysseek( POS, WHENCE )
55           Similar to $io->seek, but sets the IO::File's position using the
56           system call lseek(2) directly, so will confuse most perl IO
57           operators except sysread and syswrite (see perlfunc for full
58           details)
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60           Returns the new position, or "undef" on failure.  A position of
61           zero is returned as the string "0 but true"
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63       $io->tell
64           Returns the IO::File's current position, or -1 on error.
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SEE ALSO

67       perlfunc, "I/O Operators" in perlop, IO::Handle IO::File
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HISTORY

70       Derived from FileHandle.pm by Graham Barr <gbarr@pobox.com>
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74perl v5.30.1                      2019-11-29                 IO::Seekable(3pm)
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