Can someone please explain why this is matching at all? 

$ echo 'CME.b/ESM8' | grep -P '^CME\.b?[^/.]'
CME.b/ESM8

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In the string, 'CME.' is a literal match (ok), followed by an optional 'b' (ok, it is present), but then the forward slash '/' should not match the negated character set as this is clearly saying "anything except / or ." The above was also tested using an actual Perl script: 
#!/usr/bin/perl

use strict;
use warnings;

my $string = 'CME.b/ESM8';

if ( $string =~ /^CME\.b?[^\/.]/ )
{
    print "yes\n";
}
else {
    print "no\n";
}

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but that also indicates a match: <code> $ ./foo.pl yes {/code} I've been writing Perl regexes for years but this is really puzzling me. Tanks! Miguel

In reply to Strange negated character class behavior by miguelnyc703

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