!=(не равно) в регульрном вырожении на perl

if ($str != m/\|\d{3}\|\w{3}\|\d{5}-\d{3}\|\w{3}\|/)
{
 то то нать ....
}
  наверное так ...

http://perldoc.narod.ru/regexp2-ref.pdf

perldoc perlop :

Binary "!~" is just like "=~" except the return value is negated in
the logical sense.

Это имелось ввиду?

unless (/^...$/) {}

Ну почти так, хотелось бы в нутри regexpa
к примеру ведь можно написать /d3{3} или /d{5}
(/d{3})|(/d{5})

perldoc perlre:

"(?!pattern)"
A zero-width negative look-ahead assertion. For example
"/foo(?!bar)/" matches any occurrence of "foo" that isn't
followed by "bar". Note however that look-ahead and
look-behind are NOT the same thing. You cannot use this for
look-behind.

If you are looking for a "bar" that isn't preceded by a "foo",
"/(?!foo)bar/" will not do what you want. That's because the
"(?!foo)" is just saying that the next thing cannot be
"foo"--and it's not, it's a "bar", so "foobar" will match. You
would have to do something like "/(?!foo)...bar/" for that. We
say "like" because there's the case of your "bar" not having
three characters before it. You could cover that this way:
"/(?:(?!foo)...|^.{0,2})bar/". Sometimes it's still easier
just to say:

if (/bar/ && $` !~ /foo$/)

For look-behind see below.

Тоже не оно?