Off topic:Extracting sequence less than N length from FASTA file

Question

[atitparajuli2018]

How do I extract sequences less than 800 bp from a fasta file, I used the following command to extract but I was not successful in doing so. I still have some sequences more than 800 bp in length.

command: $ awk 'BEGIN {RS = ">" ; ORS = ""} length ($2) <= 800 {print ">"$0}' input.fasta > output.fasta