多进程并发执行的shell

#!/bin/sh
cd /root
thread=17
count=1000
start_line=1
input_file="goluk_2019009.list"
for ((i=1;i<=$thread;i++))
do
begins=`expr $start_line + $i \* $count`
echo $begins >>/root/thread.log
{
for j in `head -$begins $input_file |tail -$count`

do
wcscmd del wcs://goluk/$j >> /root/output.log 2>&1
done
}&
done