subsample

#!/usr/bin/env bash

version="GY170731"
usage="\
subsample ($version): subsampling of streamed FASTQ data
subsample [-h] <proportion>"

while getopts :h option; do
    case "$option" in
        h)
            echo "$usage"
            exit
            ;;
        \?)
            echo "$usage"
            exit 1
            ;;
    esac
done

if (( $# == 1 )) ; then
    paste - - - - \
    | awk "BEGIN {srand()} rand() < $1" \
    | tr "\t" "\n"
else
    echo "$usage"
    exit 1
fi