clash auto start and update subcribe configuration

clash.service

# edit and save this file to /usr/lib/systemd/system/clash.service
[Unit]
Description=clash
After=network.target

[Service]
WorkingDirectory="your home directory"/.config/clash
ExecStart="your home directory"/.config/clash/start-clash.sh
ExecStop="your home directory"/.config/clash/stop-clash.sh
Environment="HOME=your home directory"
Environment="CLASH_URL=your subscribe address"

[Install]
WantedBy=multi-user.target

start-clash.sh

#!/bin/bash
# save this file to ${HOME}/.config/clash/start-clash.sh

# save pid file
echo $$ > ${HOME}/.config/clash/clash.pid

diff ${HOME}/.config/clash/config.yaml <(curl -s ${CLASH_URL})
if [ "$?" == 0 ]
then
    /usr/bin/clash
else
    TIME=`date '+%Y-%m-%d %H:%M:%S'`
    cp ${HOME}/.config/clash/config.yaml "${HOME}/.config/clash/config.yaml.bak${TIME}"
    curl -L -o ${HOME}/.config/clash/config.yaml ${CLASH_URL}
    /usr/bin/clash
fi

stop-clash.sh

#!/bin/bash
# save this file to ${HOME}/.config/clash/stop-clash.sh

# read pid file
PID=`cat ${HOME}/.config/clash/clash.pid`
kill -9 ${PID}
rm ${HOME}/.config/clash/clash.pid