#!/bin/bash
lines=1000
ccount=0

while getopts l: opt 2> /dev/null
do
    case $opt in
        l) lines=$OPTARG ;;
        *) echo "Illegal option -$opt" >&2
           exit 1
        ;;
    esac
done
shift $((OPTIND-1))

if [ $# -le 0 ]
then
    cat >&2 <<EOF
linesplit:  Designed to read from standard input
            and split into multiple streams, running one command per loop
            and writing into its STDIN.  @FNAME@ is available as an
            sequence number if needed.

syntax:  linesplit [-l lines] command arguments @FNAME@ ...
EOF
    exit 1
fi

while [[ ${PIPESTATUS[0]} != 33 ]]
do
    ((ccount++))
    printf -v fname "%08d" $ccount
    for((n=0; n<lines; n++))
    do
        read line && echo "$line" || exit 33
    done | eval ${@//@FNAME@/$fname}
done

printf "Wrote %'d full chunks of %'d lines\n" $((ccount-1)) $lines >&2

$ printf "%s\n" $(seq 1 100) | ./linesplit.pl -l 10 wc -l
10
10
10
10
10
10
10
10
10
10
0
Wrote 10 chunks of 10 lines

$ printf "%s\n" $(seq 1 100) | ./linesplit.pl -l 3000 wc -l
100
Wrote 0 chunks of 3000 lines