Filter (by max length) only lines not matching regex

Shell Programming and Scripting
1

I have a large file of many pairs of sequences and their headers, which always begin with '>'

I'm looking for help on how to retain only sequences (and their headers) below a certain length. So if min length was 10, output would be

I can filter by length, but I'm not sure how to exclude the header lines.

awk '{lines[NR] = $0} length($0) < 10 {print lines [NR-1]; print lines [NR]} ' file.name
2

Do your data always come in pairs? If yes, your code is fine. Try also

$ while read HEAD; do read DATA; [ ${#DATA} -lt 10 ] && printf "%s\n%s\n" "$HEAD" "$DATA"; done < file
>gi|bcd| Species two
ATTTGATC
>gi|cdf| Species three
ATTTGATCT
1 Like
3

Like this?

awk '/^[^>]/ && length($0)<10{print hdr"\n"$0}{hdr=$0}' input
1 Like
4

Both of these work, thank you.

The problem with my original code was obscured by my choice of an example file with unrealistically short sequences. In reality my sequences are longer, and the problem with my code is that it captures headers along with short sequences.