I have a directory of many fasq files. I am using this command to count the read legnth and output into a new file.

sed -n '2~4p' FAX08345_abafd786_a8df7914_1131.fastq | awk '{ print length }' > len.text

I would like to apply this command to all of the fastq files that I have in my directory, and I need to output to create a unique file name, len.x, where x = the file name of the fastq, for example. I am working in Bash.

I would appreciate any help!

Please explain the syntax of a for loop for bash.