#! perl -slw use strict; sub rndStr{ join'', @_[ map{ rand $#_ } 1 .. shift ] } our $N //= 10e3; my $halfN = $N >> 1; my @data; $#data = $N; $data[ $_ ] = rndStr( 200 +int( rand 200 ), 'A', 'C', 'G', 'T', 'N' ) for 0 .. $halfN; $data[ $_ + $halfN ] = substr( $data[ $_ ], 10, 10 + int( rand( length( $data[ $_ ] ) - 20 ) ) ) for 0 .. $halfN; print for @data; __END__ C:\test> 906020-gen -N=10e3 > 906020.10e3