perldoc: the key to perl

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=E3=80=88Perl Documentation: The Key to Perl=E3=80=89

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So, i wanted to know what the option perl -C does. So, here's perldoc
perlrun. Excerpt:

        -C [*number/list*]
             The -C flag controls some of the Perl Unicode features.

             As of 5.8.1, the -C can be followed either by a number or
a list of
             option letters. The letters, their numeric values, and
effects are
             as follows; listing the letters is equal to summing the

                 I     1   STDIN is assumed to be in UTF-8
                 O     2   STDOUT will be in UTF-8
                 E     4   STDERR will be in UTF-8
                 S     7   I + O + E
                 i     8   UTF-8 is the default PerlIO layer for input
                 o    16   UTF-8 is the default PerlIO layer for
output streams
                 D    24   i + o
                 A    32   the @ARGV elements are expected to be
strings encoded
                           in UTF-8
                 L    64   normally the "IOEioA" are unconditional,
                           the L makes them conditional on the locale
                           variables (the LC_ALL, LC_TYPE, and LANG,
in the order
                           of decreasing precedence) -- if the
variables indicate
                           UTF-8, then the selected "IOEioA" are in
                 a   256   Set $ to -1, to run the UTF-8
caching code in
                           debugging mode.

             For example, -COE and -C6 will both turn on UTF-8-ness on
             STDOUT and STDERR. Repeating letters is just redundant,
             cumulative nor toggling.

             The "io" options mean that any subsequent open() (or
similar I/O
             operations) in the current file scope will have the
":utf8" PerlIO
             layer implicitly applied to them, in other words, UTF-8
is expected
             from any input stream, and UTF-8 is produced to any
output stream.
             This is just the default, with explicit layers in open()
and with
             binmode() one can manipulate streams as usual.

             -C on its own (not followed by any number or option
list), or the
             empty string "" for the "PERL_UNICODE" environment
variable, has
             the same effect as -CSDL. In other words, the standard I/
O handles
             and the default "open()" layer are UTF-8-fied *but* only
if the
             locale environment variables indicate a UTF-8 locale.
             behaviour follows the *implicit* (and problematic) UTF-8
             of Perl 5.8.0.

             You can use -C0 (or "0" for "PERL_UNICODE") to explicitly
             all the above Unicode features.

             The read-only magic variable "$" reflects the
             value of this setting. This variable is set during Perl
startup and
             is thereafter read-only. If you want runtime effects, use
             three-arg open() (see "open" in perlfunc), the two-arg
             (see "binmode" in perlfunc), and the "open" pragma (see

             (In Perls earlier than 5.8.1 the -C switch was a Win32-
only switch
             that enabled the use of Unicode-aware "wide system call"
             APIs. This feature was practically unused, however, and
the command
             line switch was therefore "recycled".)

             Note: Since perl 5.10.1, if the -C option is used on the
"#!" line,
             it must be specified on the command line as well, since
             standard streams are already set up at this point in the
             of the perl interpreter. You can also use binmode() to
set the
             encoding of an I/O stream.

reading that is like a adventure. It's like this:

    The -C is a key to unlock many secrets. Just get it, and you'll be
    good to go, except in cases you may need the inner key. You'll
find a
    hinge in the key, open it, then there's a subkey. On the subkey,
    there's a number. Take that number to the lock, it will open with
    keyX. When you use keyX, it must be matched with the previous
    key with 8th bit. keyX doesn't have a ID, but you can make one by
    finding the number at the place you found the key C. Key C is
    optional, but when inner key and keyX's number matches, it changes
    nature of the lock. This is when you need to turn on keyMode80=A6


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