Another issue is that single quote prevent interpolation. ... You want to use double quotes instead.

I don't understand the point you're making here. Using double-quote interpolation produces the string "\ts", which doesn't seem to be what the OPer wants to split on at all and which earns you an "Unrecognized escape ..." warning into the bargain. Indeed, in your example code, you use the  '\t\s' (a single tab character followed by any single whitespace character) as the split pattern. (Personally, I prefer to use  qr// or  m// instead. Potayto, potahto.)

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my $line = qq{foo\t bar\t\tbaz\t\nboff};
 print qq{>>$line<<};
 dd $line;
 ;;
 my @fields = split '\t\s', $line;
 dd \@fields;
"
>>foo    bar            baz
boff<<
"foo\t bar\t\tbaz\t\nboff"

["foo", "bar", "baz", "boff"]

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my $line = qq{foo\t bar\t\tbaz\t\nboff};
 print qq{>>$line<<};
 dd $line;
 ;;
 my @fields = split qq{\t\s}, $line;
 dd \@fields;
"
Unrecognized escape \s passed through at -e line 1.
>>foo    bar            baz
boff<<
"foo\t bar\t\tbaz\t\nboff"

["foo\t bar\t\tbaz\t\nboff"]
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