Hm-m, while the above solution works, but by way of nitpicking and because of TIMTOWTDI:

$1 is reset on each attempted match

$1 is reset on each successful match, and restored on each scope end. Scope end happens twice (rather, n + 1) in OP: 1st on every loop iteration (-n), second at program finishing but before executing END block(s).

>perl -wE "'a'=~/(a)/; 'a'=~/b/; say $1"
a

>perl -wE "'a'=~/(a)/; 'a'=~/a/; say $1"
Use of uninitialized value $1 in say at -e line 1.


>perl -wE "'a'=~/(a)/; END { say $1 }"
Use of uninitialized value $1 in say at -e line 1.

[download]

But we can abuse the fact that, unlike other global variables related to regular expressions, the $^R is not dynamically scoped. Further, let's match only once, and also have a little fun and save us a few keystrokes by using a secret (END will also do, of course):

>perl -ne "/^(.*) INFO.+Successfully sent(?{$1})/ }{ print $^R" file

[download]

In reply to Re^2: one liner string extraction by vr
in thread one liner string extraction by natxo

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