How to change source on schedule in ffmpeg?

Question

fmpeg

there is a script:

#!/bin/sh

ffmpeg -i http://nashe.streamr.ru/nashe-128.mp3 -i "rtsp://поток1" -tune zerolatency -vcodec libx264 -pix_fmt + -c:v copy -c:a aac -strict experimental  -f flv "rtmp://ютуб"

start from rc.local is
it necessary that after a certain time the source "stream1" changes to the next one, for example "stream2", then "stream3"
kill the previous process and start a new script according to the schedule? but I wasn't able to manually kill the ffmpeg process? it is not killed by kill pid, and the PID still needs to be determined, there are several ffmpeg processes.