You need to put the filehandle read into a scalar context to get a single line at a time, as by default print() is evaluated in a list context

print scalar <DATA>;
__DATA__
the first line
the second line
[download]

This will output "the first line". Or if you decide you need to put the file into an array I'd recommend using Dominus' Tie::File module.
HTH

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broquaint