#Attempt to capture 2 patterns by combining above regex's $newvar =~ /(?:#augment:A)(.*)(?:\n)(?:#augment:B)(.*)(?:\n)/ ; say $1; say $2; #Does not work - nothing is captured and I get uninitialized value $1 and $2 warnings...

You've been shown why this is not matching as you want, but please also consider that $1 and $2 are only uninitialized because you haven't previously successfully captured a match in your program. If you had, those variables would still contain the matches they captured earlier.

From perlre:

NOTE: Failed matches in Perl do not reset the match variables, which m
+akes it easier to write code that tests for a series of more specific
+ cases and remembers the best match.
[download]

Thus it's important to check whether the match succeeded before using $1:

#!/usr/bin/perl
use strict;
use warnings;

my $status = "it's a beautiful day but I am feeling crapy"; # note typ
+o

$status =~ /(beautiful|average|tough)/;
print "Day: $1\n";

$status =~ /(happy|alright|crappy)/;
print "Feeling: $1\n";

__END__
[download]

The above code does not give the expected results:

[22:08][nick:~/monks]$ perl 1139246.pl
Day: beautiful
Feeling: beautiful
[22:08][nick:~/monks]$
[download]

Add a test and we avoid the bug:

#!/usr/bin/perl
use strict;
use warnings;

my $status = "it's a beautiful day but I am feeling crapy"; # note typ
+o

if ( $status =~ /(beautiful|average|tough)/ ) {
  print "Day: $1\n";
} else {
  print "No match for day\n";
}

if ( $status =~ /(happy|alright|crappy)/ ) {
  print "Feeling: $1\n";
} else {
  print "No match for feeling\n";
}

__END__
[download]

Output:

[22:13][nick:~/monks]$ perl 1139246.pl
Day: beautiful
No match for feeling
[22:13][nick:~/monks]$
[download]