Thanks. That works fine. There's some issue with writing the results to a zipped file. I used a code ------ my $gz=gzopen("test.vcf.gz","wb"); $gz -> gzwrite(@dose); $gz ->gzclose; ------------------ What my intention was to get a file with contents of @dose in a compressed .gz file - test.vcf.gz What's wrong in this? I am getting a file test.vcf.gz which has just one line ! Thank you. P.