查找使用 systemctl 启动服务时使用的命令行

Question

我刚刚将系统从 14.04 升级到 16.04，除其他问题外，opendkim 不再正确启动。我有以下内容/var/log/syslog：

Sep 19 18:27:58 aurora systemd[1]: Starting DomainKeys Identified Mail (DKIM) Milter...
Sep 19 18:27:59 aurora opendkim[28496]: opendkim: usage: opendkim -p socketfile [options]
Sep 19 18:27:59 aurora opendkim[28496]: #011-A          #011auto-restart
Sep 19 18:27:59 aurora opendkim[28496]: #011-b modes    #011select operating modes
Sep 19 18:27:59 aurora opendkim[28496]: #011-c canon    #011canonicalization to use when signing
Sep 19 18:27:59 aurora opendkim[28496]: #011-d domlist  #011domains to sign
Sep 19 18:27:59 aurora opendkim[28496]: #011-D          #011also sign subdomains
Sep 19 18:27:59 aurora opendkim[28496]: #011-e name     #011extract configuration value and exit
Sep 19 18:27:59 aurora opendkim[28496]: #011-f          #011don't fork-and-exit
Sep 19 18:27:59 aurora opendkim[28496]: #011-F time     #011fixed timestamp to use when signing (test mode only)
Sep 19 18:27:59 aurora opendkim[28496]: #011-k keyfile  #011location of secret key file
Sep 19 18:27:59 aurora opendkim[28496]: #011-l          #011log activity to system log
Sep 19 18:27:59 aurora opendkim[28496]: #011-L limit    #011signature limit requirements
Sep 19 18:27:59 aurora opendkim[28496]: #011-n          #011check configuration and exit
Sep 19 18:27:59 aurora opendkim[28496]: #011-o hdrlist  #011list of headers to omit from signing
Sep 19 18:27:59 aurora opendkim[28496]: #011-P pidfile  #011file into which to write process ID
Sep 19 18:27:59 aurora opendkim[28496]: #011-q          #011quarantine messages that fail to verify
Sep 19 18:27:59 aurora opendkim[28496]: #011-Q          #011query test mode
Sep 19 18:27:59 aurora opendkim[28496]: #011-r          #011require basic RFC5322 header compliance
Sep 19 18:27:59 aurora opendkim[28496]: #011-s selector #011selector to use when signing
Sep 19 18:27:59 aurora opendkim[28496]: #011-S signalg  #011signature algorithm to use when signing
Sep 19 18:27:59 aurora opendkim[28496]: #011-t testfile #011evaluate RFC5322 message in "testfile"
Sep 19 18:27:59 aurora opendkim[28496]: #011-T timeout  #011DNS timeout (seconds)
Sep 19 18:27:59 aurora opendkim[28496]: #011-u userid   #011change to specified userid
Sep 19 18:27:59 aurora opendkim[28496]: #011-v          #011increase verbosity during testing
Sep 19 18:27:59 aurora opendkim[28496]: #011-V          #011print version number and terminate
Sep 19 18:27:59 aurora opendkim[28496]: #011-W          #011"why?!" mode (log sign/verify decision logic)
Sep 19 18:27:59 aurora opendkim[28496]: #011-x conffile #011read configuration from conffile
Sep 19 18:27:59 aurora systemd[1]: opendkim.service: Control process exited, code=exited status=64
Sep 19 18:27:59 aurora systemd[1]: Failed to start DomainKeys Identified Mail (DKIM) Milter.
Sep 19 18:27:59 aurora systemd[1]: opendkim.service: Unit entered failed state.
Sep 19 18:27:59 aurora systemd[1]: opendkim.service: Failed with result 'exit-code'.

似乎opendkim正在获取无效的命令行参数。如何找出正在使用的命令行，以及它是如何构建的？

跟踪/etc/init.d/opendkim start没有帮助，因为这只是调用 /bin/systemctl --no-pager start opendkim.service. 环顾四周，我发现/lib/systemd/system/opendkim.service其中包含该行

ExecStart=/usr/sbin/opendkim -x /etc/opendkim.conf -u opendkim -P /var/run/opendkim/opendkim.pid -p $SOCKET $DAEMON_OPTS

在 中/etc/default/opendkim，我们有SOCKET="inet:8891@localhost"并DAEMON_OPTS没有设置。但是，如果我手动运行

/usr/sbin/opendkim -x /etc/opendkim.conf -u opendkim -P /var/run/opendkim/opendkim.pid -p inet:8891@localhost

它成功了。显然，这不是正在使用的命令行。

按照 muru 的评论，这里是systemctl -l status opendkim.service.

? opendkim.service - DomainKeys Identified Mail (DKIM) Milter
   Loaded: loaded (/lib/systemd/system/opendkim.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Mon 2016-09-19 18:27:59 UTC; 23min ago
     Docs: man:opendkim(8)
           man:opendkim.conf(5)
           man:opendkim-genkey(8)
           man:opendkim-genzone(8)
           man:opendkim-testadsp(8)
           man:opendkim-testkey
           http://www.opendkim.org/docs.html
  Process: 28496 ExecStart=/usr/sbin/opendkim -x /etc/opendkim.conf -u opendkim -P /var/run/opendkim/opendkim.pid -p $SOCKET $DAEMON_OPTS (code=exited, status=64)
  Process: 28488 ExecStartPre=/bin/chown opendkim.opendkim /var/run/opendkim (code=exited, status=0/SUCCESS)
  Process: 28485 ExecStartPre=/bin/mkdir -p /var/run/opendkim (code=exited, status=0/SUCCESS)

Sep 19 18:27:59 aurora opendkim[28496]:         -T timeout          DNS timeout (seconds)
Sep 19 18:27:59 aurora opendkim[28496]:         -u userid           change to specified userid
Sep 19 18:27:59 aurora opendkim[28496]:         -v                  increase verbosity during testing
Sep 19 18:27:59 aurora opendkim[28496]:         -V                  print version number and terminate
Sep 19 18:27:59 aurora opendkim[28496]:         -W                  "why?!" mode (log sign/verify decision logic)
Sep 19 18:27:59 aurora opendkim[28496]:         -x conffile         read configuration from conffile
Sep 19 18:27:59 aurora systemd[1]: opendkim.service: Control process exited, code=exited status=64
Sep 19 18:27:59 aurora systemd[1]: Failed to start DomainKeys Identified Mail (DKIM) Milter.
Sep 19 18:27:59 aurora systemd[1]: opendkim.service: Unit entered failed state.
Sep 19 18:27:59 aurora systemd[1]: opendkim.service: Failed with result 'exit-code'.

该ExecStart行与文件中的一样。是否有可能从字面上传递字符串$SOCKET而不是该变量的内容？

Answer 1

我想到了。我尝试用/usr/sbin/opendkim记录其命令行的脚本替换，并看到它正在获取

-x /etc/opendkim.conf -u opendkim -P /var/run/opendkim/opendkim.pid -p inet:8891@localhost# listen on loopback on port 12345

行尾有一条评论/etc/default/opendkim，显然没有正确解析。

我将该评论移到了它自己的行中，现在它可以工作了。