加到systemd ExecStartPre 后无法运行

[outsinre]

[Unit]
Description=Shadowsocks-libev Default Server Service
Documentation=man:shadowsocks-libev(8)
After=network.target

[Service]
Type=simple
EnvironmentFile=/etc/sysconfig/shadowsocks-libev
User=nobody
Group=nobody
LimitNOFILE=32768
ExecStart=/usr/bin/ss-server -c $CONFFILE $DAEMON_ARGS

[Install]
WantedBy=multi-user.target


# /etc/systemd/system/shadowsocks-libev.service.d/override.conf
[Service]
ExecStartPre=/usr/bin/python3.4 /opt/ptproxy/ptproxy.py -s /opt/ptproxy/server.json >/dev/null &

这里我吧ptproxy加到ss-libev的unit file ExecStartPre处，可是运行不了，journalctl 里面全是：

Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 PT died.
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 Starting PT...
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 PT died.
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 Starting PT...
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 PT died.
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 Starting PT...
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 PT died.
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 Starting PT...
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 PT died.
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 Starting PT...
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 PT died.
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 Starting PT...
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 PT died.
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 Starting PT...
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 PT died.
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 Starting PT...
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 PT died.
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 Starting PT...
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 PT died.
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 Starting PT...
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 PT died.
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 Starting PT...
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 PT died.
Nov 14 04:57:32 localhost python3.4[15994]: 2017-11-14 04:57:32 Starting PT...

同样的命令在terminal直接运行没有问题：

~ # /usr/bin/python3.4 /opt/ptproxy/ptproxy.py -s /opt/ptproxy/server.json >/dev/null &
~ # su nobody -s /bin/bash -c "/usr/bin/python3.4 /opt/ptproxy/ptproxy.py -s /opt/ptproxy/server.json >/dev/null &"

pt_state 所有者 nobody:nobody。

[gumblex]

怀疑是权限问题。去掉 >/dev/null 看日志？