IO::Seekable(3p) Perl Programmers Reference Guide IO::Seekable(3p)

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)