linux – Systemd退出bash脚本,执行导致失败的命令,而不是继续

我正在尝试获取一个脚本,将我在CoreOS上的系统日志推送到logentries.为了弥补实例在AWS上运行时没有立即连接互联网的事实,我将命令停留在while循环中.

从命令行运行脚本while循环工作正常.但是当systemd运行它时,当netcat超时时它会立即退出,所以它再也没有机会再试一次.

有没有办法让systemd在退出脚本时不那么积极？

systemd输出,永远不会到“睡觉netcat”

Jul 23 22:26:21 core-01 systemd[1]: Starting Push journal logs to logentries.com...
Jul 23 22:26:21 core-01 systemd[1]: Started Push journal logs to logentries.com.
Jul 23 22:26:21 core-01 bash[880]: trying netcat
Jul 23 22:26:31 core-01 bash[880]: Ncat: Connection timed out.

journal2logentries.sh

#!/usr/bin/env bash
token=logentriestoken
while true
do
  echo 'trying netcat'
  journalctl -o short -f | awk -v token=$token '{ print token,$0; fflush(); }' | ncat --ssl --ssl-verify data.logentries.com 20000
  echo 'sleeping netcat'
  sleep 30s
done

logentries.service

[Unit] 
Description=Push journal logs to logentries.com 
After=systemd-journald.service
After=systemd-networkd.service

[Service]
Restart=always
ExecStart=/bin/bash /home/core/journal2logentries.sh

[Install]
WantedBy=multi-user.target

更新：

似乎真正的问题是,当netcat死掉系统时,/ bin / sh进程仍在运行.注意：url故意不正确测试

logentries.service - Push journal logs to logentries.com
   Loaded: loaded (/etc/systemd/system/logentries.service; disabled)
   Active: active (running) since Mon 2014-07-28 17:12:04 UTC; 1min 48s ago
 Main PID: 16305 (sh)
   CGroup: /system.slice/logentries.service
           ├─16305 /bin/sh -c journalctl -o short -f | awk -v token=token_here '{ print token,$0; fflush(); }' | ncat --ssl --ssl-verify -vv ogentries.com 20000
           ├─16306 journalctl -o short -f
           └─16307 awk -v token=80b4b3b6-1315-4b76-ac69-f530c1dec47f { print token,$0; fflush(); }

Jul 28 17:12:04 ip-172-31-19-155.us-west-2.compute.internal systemd[1]: logentries.service holdoff time over,scheduling restart.
Jul 28 17:12:04 ip-172-31-19-155.us-west-2.compute.internal systemd[1]: Stopping Push journal logs to logentries.com...
Jul 28 17:12:04 ip-172-31-19-155.us-west-2.compute.internal systemd[1]: Starting Push journal logs to logentries.com...
Jul 28 17:12:04 ip-172-31-19-155.us-west-2.compute.internal systemd[1]: Started Push journal logs to logentries.com.
Jul 28 17:12:04 ip-172-31-19-155.us-west-2.compute.internal sh[16305]: Ncat: Version 6.40 ( http://nmap.org/ncat )
Jul 28 17:12:04 ip-172-31-19-155.us-west-2.compute.internal sh[16305]: Ncat: Could not resolve hostname "ogentries.com": Name or service not kNown. QUITTING.

解决方法

从管道切换到处理替换.

http://paraf.in/abs-guide/process-sub.html

https://stackoverflow.com/a/18360260/136408

这是我提出的单元文件：

logentries.service

[Unit]
Description=Push journal logs to logentries.com
After=systemd-journald.service
After=systemd-networkd.service

[Service]
Restart=always
RestartSec=30s
ExecStart=/bin/bash -c "ncat --ssl --ssl-verify data.logentries.com 20000 < <(awk -v token=token_here '{ print token,$0; fflush(); }' < <(journalctl -o short -f))"

[Install]
WantedBy=multi-user.target