Hi,
I want to do psiblast in command line. Before, performing psiblast, I tried to make a blast database by using makeblastdb command. But it shows the following error:

    BLAST Database creation error: Error: Duplicate seq_ids are found:
    REF|WP_003261842.1
My fasta file is very large. So, manual deletion of the duplicate sequence is nearly impossible. How can I get rid from the duplication? 

Cheers 

Use [seqkit][1]:

    $ seqkit rmdup input.fa > output.fa


  [1]: https://bioinf.shenwei.me/seqkit/usage/#rmdup