However, I want to sort these files with respect to their first digit.

First digit or first number? if digit, the 201.200.force.0.5.1LGY.pdb comes before 9.10.force.0.5.1LGY.pdb, since 2 (from 201) is lower than 9. If you want to sort by the first number, do a Schwartzian transform: 

no warnings "numeric";
@sorted = map $_->[0],
            sort { $a->[1] <=> $b->[1] }
              map { [ $_, int $_ ] } @unsorted;

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In reply to Re: sorting an array of file names by shmem
in thread sorting an array of file names by hotel

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