参考https://github.com/mellow-io/mellow/blob/master/scripts/run_linux.sh

clash-tun-script.sh

#!/bin/sh

# You have to configure "tun", "interface-name" and "dns" for clash to use this script
# ref: https://github.com/Dreamacro/clash/wiki/configuration
#      https://github.com/Dreamacro/clash/wiki/premium-core-features#tun-device

if [ `id -u` -ne 0 ]; then
  echo 'Must run as root!'
  exit 1
fi

if [ ! -f "/etc/clash-tun.conf" ]; then
  if [ $SUDO_USER ]; then
    echo /home/$SUDO_USER > /etc/clash-tun.conf
  else
    SUDO_USER=(`ls /home`)
    echo /home/$SUDO_USER > /etc/clash-tun.conf
  fi
fi

USER_HOME=`cat /etc/clash-tun.conf`
LOCAL_SOCKET=127.0.0.1:7891
TUN_GW=198.18.0.1
TUN_ADDR=198.18.0.1
TUN_MASK=255.255.0.0
ORIG_GW=`ip route get 1 | awk '{print $3;exit}'`
ORIG_ST_SCOPE=`ip route get 1 | awk '{print $5;exit}'`
ORIG_ST=`ip route get 1 | awk '{print $7;exit}'`

echo "Original send through address $ORIG_ST"
echo "Original send through scope $ORIG_ST_SCOPE"
echo "Original gateway $ORIG_GW"

config_route() {
  # Give some time for Mellow to open the TUN device.
  sleep 3
  # tun_ver="v0.17.1\n"`clash -v|awk '{print $2;exit}'|awk -F- '{print $1;exit}'`"\n"
  # ret=`echo $tun_ver|sort -V`
#  if [ "$ret"x = "$tun_ver"x ]; then
#    echo 'Wake up tun...'
#    ip link set clash0 up
#    ip addr add $TUN_GW dev clash0
#  fi
  
  echo 'Setting up routing table...'
  ip route del default table main
  ip route add default via $TUN_GW table main
  ip route add default via $ORIG_GW dev $ORIG_ST_SCOPE table default
  ip rule add from $ORIG_ST table default
  mv /etc/resolv.conf /etc/resolv.conf.bak
  echo "nameserver 127.0.0.1" > /etc/resolv.conf
}

recover_route() {
  echo 'Recovering routing table...'
  ip rule del from $ORIG_ST table default
  ip route del default table default
  ip route del default table main
  ip route add default via $ORIG_GW table main
  mv /etc/resolv.conf.bak /etc/resolv.conf
}

# Configure the routing table in the background.
config_route&

clash-tun -d $USER_HOME/.config/clash

# Recover the routing table after clash exits.
recover_route