Thank you very much for your efforts. I am obviously not able to explain very well what I am trying to do. This seems to put all the sequences in one single element of the @seq array, and the length includes the header ( not just the seq data).

I just want to extract all the sequences with a minimal length. But the sequences need to still be in fasta format. How can I use the regex for > to extract the sequence in between the headers and check the length? Since each line of sequence has a newline in between.

Thanks again and sorry for not being able to explain. /Sofie