Win8 Strawberry 5.8.9.5 (32)  Tue 03/16/2021 21:10:53
C:\@Work\Perl\monks
>perl -Mstrict -Mwarnings

my $abc = 'dgrs';
$_ = 1;

# print $temp_out "$abc . _$_;\n";  # not this, with extra dot and spaces
print 'A: ', $abc . "_$_", "\n";    # but this ...
print 'B: ', "${abc}_$_", "\n";     # or this.
print "C: ${abc}_$_;\n";            # update: or even this.

^Z
A: dgrs_1
B: dgrs_1
C: dgrs_1;