This depends on just how you define 'everything except sequence xyz'.

One way (note that a piece of 'xyz', the 'yz', is captured – after all, 'yz' is not 'xyz'!): 

>perl -wMstrict -le
"my $s = 'abcxyzdef';
 my $exclude = qr{ xyz }xms;
 my $all_not_xyz = qr{ (?! $exclude) . }xms;
 my @matches = $s =~ m{ ($all_not_xyz+) }xmsg;
 print qq{@matches};
"
abc yzdef

[download]
Another way (note that the 'xyz' sequence is entirely excluded): 
>perl -wMstrict -le
"my $s = 'abcxyzdef';
 my $exclude = qr{ xyz }xms;
 my @matches = split m{ $exclude }xms, $s;
 print qq{@matches};
"
abc def

[download]
These approaches generalize nicely to multiple exclusion sequences: 
>perl -wMstrict -le
"my $s = 'abcFOOdefBARghi';
 my $exclude = qr{ FOO | BAR }xms;
 my $all_but = qr{ (?! $exclude) . }xms;
 my @matches = $s =~ m{ ($all_but+) }xmsg;
 print qq{@matches};
 @matches = split m{ $exclude }xms, $s;
 print qq{@matches};
"
abc OOdef ARghi
abc def ghi

[download]

In reply to Re: match with exception by AnomalousMonk
in thread match with exception by vit

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.