perl -lne 'print if s/^(.{188})[1-9]\d{7}(.{16})$/${1}20020101$2/' original.txt > new.txt 

##</code><code>##

while(<>) {
 next unless /^(.{188})(\d{8})(.{16})$/;
 print $1,"20020101$3\n" unless $2 eq '00000000';
}