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MAN page from CentOS 8 perl-IO-1.40-452.module_el8.4.0+646+45e06e4a.x86_64.rpm

IO::Seekable

Section: Perl Programmers Reference Guide (3pm)
Updated: 2019-10-24
Index 

NAME

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

SYNOPSIS

    use IO::Seekable;    package IO::Something;    @ISA = qw(IO::Seekable);
 

DESCRIPTION

"IO::Seekable" does not have a constructor of its own as it is intended tobe inherited by other "IO::Handle" based objects. It provides methodswhich allow seeking of the file descriptors.
$io->getpos
Returns an opaque value that represents the current position of theIO::File, or "undef" if this is not possible (eg an unseekable stream suchas a terminal, pipe or socket). If the fgetpos() function is available inyour C library it is used to implements getpos, else perl emulates getposusing C's ftell() function.
$io->setpos
Uses the value of a previous getpos call to return to a previously visitedposition. Returns ``0 but true'' on success, "undef" on failure.

See perlfunc for complete descriptions of each of the followingsupported "IO::Seekable" methods, which are just front ends for thecorresponding built-in functions:

$io->seek ( POS, WHENCE )
Seek the IO::File to position POS, relative to WHENCE:
WHENCE=0 (SEEK_SET)
POS is absolute position. (Seek relative to the start of the file)
WHENCE=1 (SEEK_CUR)
POS is an offset from the current position. (Seek relative to current)
WHENCE=2 (SEEK_END)
POS is an offset from the end of the file. (Seek relative to end)

The SEEK_* constants can be imported from the "Fcntl" module if youdon't wish to use the numbers 0 1 or 2 in your code.

Returns 1 upon success, 0 otherwise.

$io->sysseek( POS, WHENCE )
Similar to $io->seek, but sets the IO::File's position using the systemcall lseek(2) directly, so will confuse most perl IO operators exceptsysread and syswrite (see perlfunc for full details)

Returns the new position, or "undef" on failure. A positionof zero is returned as the string "0 but true"

$io->tell
Returns the IO::File's current position, or -1 on error.
 

SEE ALSO

perlfunc, ``I/O Operators'' in perlop,IO::HandleIO::File 

HISTORY

Derived from FileHandle.pm by Graham Barr <gbarrAATTpobox.com>


 

Index

NAME
SYNOPSIS
DESCRIPTION
SEE ALSO
HISTORY

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