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Интерактивная система просмотра системных руководств (man-ов)

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re (3)
  • >> re (3) ( Solaris man: Библиотечные вызовы )
  • re (3) ( Linux man: Библиотечные вызовы )
  • re (4) ( FreeBSD man: Специальные файлы /dev/* )


         re - Perl pragma to alter regular expression behaviour


             use re 'taint';
             ($x) = ($^X =~ /^(.*)$/s);     # $x is tainted here
             $pat = '(?{ $foo = 1 })';
             use re 'eval';
             /foo${pat}bar/;                # won't fail (when not under -T switch)
                 no re 'taint';             # the default
                 ($x) = ($^X =~ /^(.*)$/s); # $x is not tainted here
                 no re 'eval';              # the default
                 /foo${pat}bar/;            # disallowed (with or without -T switch)
             use re 'debug';                # NOT lexically scoped (as others are)
             /^(.*)$/s;                     # output debugging info during
                                            #     compile and run time
             use re 'debugcolor';           # same as 'debug', but with colored output
         (We use $^X in these examples because it's tainted by


         When `use re 'taint'' is in effect, and a tainted string is
         the target of a regex, the regex memories (or values
         returned by the m// operator in list context) are tainted.
         This feature is useful when regex operations on tainted data
         aren't meant to extract safe substrings, but to perform
         other transformations.
         When `use re 'eval'' is in effect, a regex is allowed to
         contain `(?{ ... })' zero-width assertions even if regular
         expression contains variable interpolation.  That is
         normally disallowed, since it is a potential security risk.
         Note that this pragma is ignored when the regular expression
         is obtained from tainted data, i.e.  evaluation is always
         disallowed with tainted regular expresssions.  See the
         section on "(?{ code })" in the perlre manpage.
         For the purpose of this pragma, interpolation of precompiled
         regular expressions (i.e., the result of `qr//') is not
         considered variable interpolation.  Thus:
         is allowed if $pat is a precompiled regular expression, even
         if $pat contains `(?{ ... })' assertions.
         When `use re 'debug'' is in effect, perl emits debugging
         messages when compiling and using regular expressions.  The
         output is the same as that obtained by running a
         `-DDEBUGGING'-enabled perl interpreter with the -Dr switch.
         It may be quite voluminous depending on the complexity of
         the match.  Using `debugcolor' instead of `debug' enables a
         form of output that can be used to get a colorful display on
         terminals that understand termcap color sequences.  Set
         `$ENV{PERL_RE_TC}' to a comma-separated list of `termcap'
         properties to use for highlighting strings on/off, pre-point
         part on/off. See the Debugging regular expressions entry in
         the perldebug manpage for additional info.
         The directive `use re 'debug'' is not lexically scoped, as
         the other directives are.  It has both compile-time and
         run-time effects.
         See the Pragmatic Modules entry in the perlmodlib manpage.

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