IO::Seekable(3p) Perl Programmers Reference Guide IO::Seekable(3p) #
IO::Seekable(3p) Perl Programmers Reference Guide IO::Seekable(3p)
NNAAMMEE #
IO::Seekable - supply seek based methods for I/O objects
SSYYNNOOPPSSIISS #
use IO::Seekable;
package IO::Something;
@ISA = qw(IO::Seekable);
DDEESSCCRRIIPPTTIIOONN #
"IO::Seekable" does not have a constructor of its own as it is intended
to be inherited by other "IO::Handle" based objects. It provides methods
which allow seeking of the file descriptors.
$io->getpos
Returns an opaque value that represents the current position of the
IO::File, or "undef" if this is not possible (eg an unseekable stream
such as a terminal, pipe or socket). If the ffggeettppooss(()) function is
available in your C library it is used to implements getpos, else
perl emulates getpos using C's fftteellll(()) function.
$io->setpos
Uses the value of a previous getpos call to return to a previously
visited position. Returns "0 but true" on success, "undef" on
failure.
See perlfunc for complete descriptions of each of the following supported
"IO::Seekable" methods, which are just front ends for the corresponding
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 you
don'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
system call llsseeeekk(2) directly, so will confuse most perl IO operators
except sysread and syswrite (see perlfunc for full details)
Returns the new position, or "undef" on failure. A position of zero
is returned as the string "0 but true"
$io->tell
Returns the IO::File's current position, or -1 on error.
SSEEEE AALLSSOO #
perlfunc, "I/O Operators" in perlop, IO::Handle IO::File
HHIISSTTOORRYY #
Derived from FileHandle.pm by Graham Barr <gbarr@pobox.com>
perl v5.36.3 2023-02-15 IO::Seekable(3p)