Case

#!/bin/sh
 
trap cleanup 1 2 3 6 15
 
cleanup()
{
    killall wget
    exit 1
}
 
while test true
do
    vdir=`date "+%Y-%m-%d-%H"`
    if ! [ -e $vdir ]
    then
        mkdir $vdir
    fi
 
    filename=`date "+%Y-%m-%d-%H-%M-%S"`
    wget --tries=0 -o /dev/null -O "$vdir/$filename.mpg" http://172.16.127.4:8080 &
 
    i=1
    while [ $i -lt 60 ]
    do  
        sleep 2
        sfile=`date +%s`
 
        sdir=`date "+%Y-%m-%d-%H"`
        if ! [ -e $sdir ]
        then
            mkdir $sdir
        fi
 
        let sfile = $sfile + 2
        if [ -s "$vdir/$filename.mpg" ]
        then
            ffmpeg -i "$vdir/$filename.mpg" -an -ss 00:00:$i -r 1 -vframes 1 -y -f mjpeg "$sdir/$sfile.jpg" && if [ -s "$sdir/$sfile.jpg" ]; then rm final.jpg; ln "$sdir/$sfile.jpg" final.jpg; fi &
        fi
        let i = $i + 2
 
        if [ -e stop ]
        then
            rm stop
            cleanup
        fi
    done
 
    killall wget
done