bash 在脚本中检查 SSH 失败
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Checking SSH failure in a script
提问by theuniverseisflat
Hi what is the best way to check to see if SSH fails for whatever reason? Can I use a IF statement ( if it fails then do something) I'm using the ssh command in a loop and passing my hosts names form a flat file.
嗨，检查 SSH 是否因任何原因失败的最佳方法是什么？我可以使用 IF 语句吗（如果它失败然后做一些事情）我在循环中使用 ssh 命令并传递我的主机名形成一个平面文件。
so I do something like:
所以我做这样的事情：
for i in `cat /tmp/hosts` ; do ssh $i 'hostname;sudo ethtool eth1'; done
I get sometime this error or I just cannot connect
我有时会收到此错误，或者我无法连接
ssh: host1 Temporary failure in name resolution
I want to skip the hosts that I cannot connect to is SSH fails. What is the best way to do this? Is there a runtime error I can trap to bypass the hosts that I cannot ssh into for whatever reason, perhaps ssh is not allowed or I do not have the right password ?
我想跳过我无法连接的主机是 SSH 失败。做这个的最好方式是什么？是否存在运行时错误，我可以捕获以绕过出于任何原因无法 ssh 进入的主机，也许 ssh 不被允许或我没有正确的密码？
Thanking you in advance Cheers
提前致谢
采纳答案by wbt11a
You can check the return value that ssh gives you as originally shown here: How to create a bash script to check the SSH connection?
您可以检查 ssh 为您提供的返回值，如下所示： How to create a bash script to check the SSH connection?
$ ssh -q user@downhost exit
$ echo $?
255
$ ssh -q user@uphost exit
$ echo $?
0
EDIT - I cheated and used nc
编辑 - 我作弊并使用了 nc
Something like this:
像这样的东西：
#!/bin/bash
ssh_port_is_open() { nc -z ${1:?hostname} 22 > /dev/null; }
for host in `cat /tmp/hosts` ; do
if ssh_port_is_open $host; then
ssh -o "BatchMode=yes" $i 'hostname; sudo ethtool eth1';
else
echo " $i Down"
fi
done
回答by that other guy
To check if there was a problem connecting and/or running the remote command:
要检查连接和/或运行远程命令是否有问题：
if ! ssh host command
then
echo "SSH connection or remote command failed"
fi
To check if there was a problem connecting, regardless of success of the remote command (unless it happens to return status 255, which is rare):
要检查是否存在连接问题，无论远程命令是否成功（除非它碰巧返回状态 255，这种情况很少见）：
if ssh host command; [ $? -eq 255 ]
then
echo "SSH connection failed"
fi
Applied to your example, this would be:
应用于您的示例，这将是：
for i in `cat /tmp/hosts` ;
do
if ! ssh $i 'hostname;sudo ethtool eth1';
then
echo "Connection or remote command on $i failed";
fi
done
