#!/bin/bash

_cam=00
_source="rtsp://lan.merx.pl:2554/live/ch${_cam}/0"
_webspace="/var/www/vhosts/webspace.ltd/htdocs"
_cmd="ffmpeg -i $_source -f image2 -vf fps=fps=3 $_webspace/cache${_cam}/%04d.jpg"

# sample: ffmpeg -i rtsp://lan.merx.pl:1554/live/ch${_cam}_00_01 -f image2 -vf fps=fps=3 cache${_cam}/%04d.jpg

cd "$_webspace"
$_cmd