rb@test:~/community$ perl -le 'my $var = "a   b  c  "; print join "::", split /[ \t]+/, $var'
a::b::c
rb@test:~/community$ perl -le 'my $var = "  a   b  c  "; print join "::", split /[ \t]+/, $var'
::a::b::c
rb@test:~/community$ perl -le 'my $var = "  a   b  c  "; print join "::", split " ", $var'
a::b::c