This is an old revision of the document!

SED - Delete - Delete all lines of a file with N characters

sed -s -i -r '/^.{9}$/d' ./*.txt

Use AWK

awk -v n=5 '{ line = $0; gsub("[^[:graph:]]", "") } length >= 23 { print line }'

NOTE: Anything over 23 characters it will delete …you can change 23 to any value.