You seem totally confident concerning the value of @a, without presenting any reasons or evidence. How about running a little test script:

#!/agl/tools/perl/bin/perl
use strict;               # Notice these two 
use warnings;             # essential modifications!
my @a=qx (rsh -l sonaxisz 'source.login ; findbug -p | sort -u | %s se
+rver');
print '@a contains ' . scalar @a . "elements:\n", @a;\
[download]

Betcha a mug of Trappist Ale you'll be surprised at the output.

--
TTTATCGGTCGTTATATAGATGTTTGCA