編輯：
我編寫了一個 python 腳本，該腳本在啟用 TLS 選項的情況下啟動 mosquitto 用戶端。當我從命令列運行它時一切正常（沒有 sudo）。現在重新安裝一些軟體包後它就壞了。
但是，我需要該腳本在系統啟動時啟動，因此我建立了一個 SYSTEMD 服務作為守護程式運行。根據服務狀態報告，我推斷cert或key文件不可用，因此守護程序有錯誤。這些檔案與 .py 腳本位於同一目錄中。有什麼想法可能是什麼問題嗎？
pi@raspberrypi:~/FONA_PROJECT $ sudo systemctl status fonagps.service
● fonagps.service - Vechicle Tracking System
Loaded: loaded (/lib/systemd/system/fonagps.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Mon 2018-03-19 22:17:59 UTC; 3s ago
Process: 1526 ExecStart=/usr/bin/python /home/pi/FONA_PROJECT/iot_sub.py (code=exited, status=1/FAILURE)
Main PID: 1526 (code=exited, status=1/FAILURE)
Mar 19 22:17:59 raspberrypi systemd[1]: Started Vechicle Tracking System.
Mar 19 22:17:59 raspberrypi python[1526]: Traceback (most recent call last):
Mar 19 22:17:59 raspberrypi python[1526]: File "/home/pi/FONA_PROJECT/iot_sub.py", line 129, in <module>
Mar 19 22:17:59 raspberrypi python[1526]: client.tls_set(ca_certs=ca_certs, certfile=certfile, keyfile=keyfile, cert_reqs=ssl.CERT_REQUIRED, tls_version=ssl.PROTOCOL_TLSv1_2, ciphers=None)
Mar 19 22:17:59 raspberrypi python[1526]: File "/usr/local/lib/python2.7/dist-packages/paho/mqtt/client.py", line 694, in tls_set
Mar 19 22:17:59 raspberrypi python[1526]: context.load_cert_chain(certfile, keyfile)
Mar 19 22:17:59 raspberrypi python[1526]: IOError: [Errno 2] No such file or directory
Mar 19 22:17:59 raspberrypi systemd[1]: fonagps.service: Main process exited, code=exited, status=1/FAILURE
Mar 19 22:17:59 raspberrypi systemd[1]: fonagps.service: Unit entered failed state.
Mar 19 22:17:59 raspberrypi systemd[1]: fonagps.service: Failed with result 'exit-code'.