任何人都知道这个全局变量是做什么的？
由于特殊字符，谷歌无法找到任何信息。
更新
[root@dev-test v2]$ perldoc -v '%^H'
Ending switch processing. Args are [%^H] with 0 errors.
/usr/bin/perldoc => Pod::Perldoc v3.14
Formatter class Pod::Perldoc::ToMan successfully loaded!
Will format with the class Pod::Perldoc::ToMan
Searching for %^H
Looking for %^H in /usr/bin /usr/lib64/perl5/site_perl/5.8.8/x86_64-linux-thread-multi /usr/lib64/perl5/site_perl/5.8.7/x86_64-linux-thread-multi /usr/lib64/perl5/site_perl/5.8.6/x86_64-linux-thread-multi /usr/lib64/perl5/site_perl/5.8.5/x86_64-linux-thread-multi /usr/lib/perl5/site_perl/5.8.8 /usr/lib/perl5/site_perl/5.8.7 /usr/lib/perl5/site_perl/5.8.6 /usr/lib/perl5/site_perl/5.8.5 /usr/lib/perl5/site_perl /usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi /usr/lib64/perl5/vendor_perl/5.8.7/x86_64-linux-thread-multi /usr/lib64/perl5/vendor_perl/5.8.6/x86_64-linux-thread-multi /usr/lib64/perl5/vendor_perl/5.8.5/x86_64-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.8 /usr/lib/perl5/vendor_perl/5.8.7 /usr/lib/perl5/vendor_perl/5.8.6 /usr/lib/perl5/vendor_perl/5.8.5 /usr/lib/perl5/vendor_perl /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi /usr/lib/perl5/5.8.8 . /usr/kerberos/bin /usr/lib64/ccache /usr/local/bin /bin /usr/bin
No documentation found for "%^H".
答案 0 :(得分：8)
来自http://perldoc.perl.org/perlvar.html：
•
%^H
%^H哈希提供与$^H相同的范围语义。这使得它有助于实现词法范围的pragma。请参阅perlpragma。此变量已添加到Perl 5.6中。