I'm not sure you can in pure bash, but you can with awk (I think).
If you make the record separator n>
rather than n
, and the field separator n
, I think you should be able to do:
awk -v RS="n>" -v FS="n" '$1=="NODE_19_length_5758_cluster_19_candidate_1" {print ">"$0}' my_fasta.fasta