You could just do this: 
my $substit = quotemeta (".1.3.5.7.9.1")
for my $key (keys %hash) {
     my $value = $hash{$key);
     $key =~ s/^$substit/SOME_DATA/;
     print "$key = $value\n"
}

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In reply to Re^3: compare text file and print occurrence of key and value by Laurent_R
in thread compare text file and print occurrence of key and value by waytoperl

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