fcntl(3pm) [redhat man page]

Fcntl(3pm)						 Perl Programmers Reference Guide						Fcntl(3pm)

NAME

       Fcntl - load the C Fcntl.h defines

SYNOPSIS

	   use Fcntl;
	   use Fcntl qw(:DEFAULT :flock);

DESCRIPTION

       This module is just a translation of the C fnctl.h file.  Unlike the old mechanism of requiring a translated fnctl.ph file, this uses the
       h2xs program (see the Perl source distribution) and your native C compiler.  This means that it has a far more likely chance of getting the
       numbers right.

NOTE

       Only "#define" symbols get translated; you must still correctly pack up your own arguments to pass as args for locking functions, etc.

EXPORTED SYMBOLS

       By default your system's F_* and O_* constants (eg, F_DUPFD and O_CREAT) and the FD_CLOEXEC constant are exported into your namespace.

       You can request that the flock() constants (LOCK_SH, LOCK_EX, LOCK_NB and LOCK_UN) be provided by using the tag ":flock".  See Exporter.

       You can request that the old constants (FAPPEND, FASYNC, FCREAT, FDEFER, FEXCL, FNDELAY, FNONBLOCK, FSYNC, FTRUNC) be provided for compati-
       bility reasons by using the tag ":Fcompat".  For new applications the newer versions of these constants are suggested (O_APPEND, O_ASYNC,
       O_CREAT, O_DEFER, O_EXCL, O_NDELAY, O_NONBLOCK, O_SYNC, O_TRUNC).

       For ease of use also the SEEK_* constants (for seek() and sysseek(), e.g. SEEK_END) and the S_I* constants (for chmod() and stat()) are
       available for import.  They can be imported either separately or using the tags ":seek" and ":mode".

       Please refer to your native fcntl(2), open(2), fseek(3), lseek(2) (equal to Perl's seek() and sysseek(), respectively), and chmod(2) docu-
       mentation to see what constants are implemented in your system.

       See perlopentut to learn about the uses of the O_* constants with sysopen().

       See "seek" in perlfunc and "sysseek" in perlfunc about the SEEK_* constants.

       See "stat" in perlfunc about the S_I* constants.

perl v5.8.0							    2002-06-01								Fcntl(3pm)

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

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 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 fgetpos() function is available in your C library it is used to implements getpos,
	   else perl emulates getpos using C's ftell() 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 lseek(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.

SEE ALSO

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

HISTORY

       Derived from FileHandle.pm by Graham Barr <gbarr@pobox.com>

perl v5.12.1							    2010-04-26							 IO::Seekable(3pm)