Thank you very much choroba. This works !!!

One last thing I need to extend to below match also

foo_bar_foo10.1.1.1.TEST.txt
foo_test_foo10.1.1.1.foo10.1.1.1.TEST_test.txt
foo_test_foo10.1.1.1.foo10.1.1.1.txt 
foo_test_foo10.1.1.1.foo10.1.1.1.TEST-1.txt

[download]

Third string is not a correct match but this is displayed as "Ok" whereas fourth doesn't seems ok but I want to match this also

for "foo_test_foo10.1.1.1.foo10.1.1.1.TEST-1.txt" I modified the expression as (\w\-{1,10}) and that works ... Is this correct way ?

trying to achieve the third format within the same format - as Nok

Output for now 1 ok 2 ok 3 ok 4 ok

Does this approach allows to use variable inside the regex format ?

Can I declare like my $var = foo10.1.1.1 and use this in regex format ?

Yes it does ... found answer for $var declaration I replaced  ((?:\w+\.)+) as ((?:($var)+\.)+) ==> Is this correct too

Last thing I am not able to get

3 is not correct .... I want to filter this out

OR

foo_test_foo10.1.1.1.foo10.1.1.1.txt - How to match only this in a separate regex

In reply to Re^2: Regex lookahead, lookbehind by rahulme81
in thread Regex lookahead, lookbehind by rahulme81

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