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fcntl(3pm) [osx man page]

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

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 fcntl.h file. Unlike the old mechanism of requiring a translated 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 compatibility 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) documentation 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 v5.16.2 2012-10-11 Fcntl(3pm)

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

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 by Graham Barr <> perl v5.18.2 2013-11-04 IO::Seekable(3pm)
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