Just for completeness: 
next unless ($Var=~/^_[A-Z][A-Z_128]+$/);

[download]
catches the following: 
_SC_2_C_BIN             _POSIX2_C_BIND     
_SC_2_C_DEV             _POSIX2_C_DEV      
_SC_2_C_VERSION         _POSIX2_C_VERSION  
_SC_2_CHAR_TERM         _POSIX2_CHAR_TERM  
_SC_2_FORT_DEV          _POSIX2_FORT_DEV   
_SC_2_FORT_RUN          _POSIX2_FORT_RUN   
_SC_2_LOCALEDEF         _POSIX2_LOCALEDEF  
_SC_2_SW_DEV            _POSIX2_SW_DEV     
_SC_2_UPE               _POSIX2_UPE        
_SC_2_VERSION           _POSIX2_VERSION    
_SC_XOPEN_ENH_I18N      _XOPEN_ENH_I18N

[download]


p

In reply to Re: Get your system configuration from a man page. by petral
in thread Get your system configuration from a man page. by ChOas

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.