Using seek to return to the beginning of the file for the <DATA> filehandle will do something that you may consider unexpected. It will seek to the beginning of the literal file in which the __DATA__ block exists. What I mean by that is that after seeking to the beginning of the file, the first line you read in is going to be your shebang line, the next line will be your use strict; line, and so on. You've successfully seeked to the start of your entire Perl script.

If you want to seek to the beginning of the data segment instead of the start of the script, you must first use tell to find where the data segment begins. Save the info from tell into a scalar. Then go ahead and walk through the <DATA> filehandle as desired. When you decide it's time to reset to the beginning of the __DATA__ segment, seek to the beginning of the segment by feeding seek the scalar variable that is holding onto where the segment begins, provided by that first call to tell.

Here's a snippet:

my $bof_DATA = tell DATA; # Save the location of DATA BOF.
my @slurp = <DATA>;       # Read in the DATA segment.
seek DATA,$bof_DATA,0;    # Return to the beginning of the
                          # DATA segment.
local $, = ", ";
print <DATA>, "\n";       # Run through DATA a second time.
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