通过ssh从bash脚本内执行远程主机上的命令 [英] Execute a command on remote hosts via ssh from inside a bash script

问题描述

我写这应该从文件中读取用户名和IP地址，并通过ssh对它们执行的命令的bash脚本。

I wrote a bash script which is supposed to read usernames and IP addresses from a file and execute a command on them via ssh.

这是HOSTS.TXT：

This is hosts.txt :

user1 192.168.56.232
user2 192.168.56.233

这是myScript.sh：

This is myScript.sh :

cmd="ls -l"

while read line
do
   set $line
   echo "HOST:" $1@$2
   ssh $1@$2 $cmd
   exitStatus=$?
   echo "Exit Status: " $exitStatus
done < hosts.txt

的问题是，执行似乎停止第一主机完成后。这是输出：

The problem is that execution seems to stop after the first host is done. This is the output:

$ ./myScript.sh
HOST: user1@192.168.56.232
total 2748
drwxr-xr-x 2 user1 user1    4096 2011-11-15 20:01 Desktop
drwxr-xr-x 2 user1 user1    4096 2011-11-10 20:37 Documents
...
drwxr-xr-x 2 user1 user1    4096 2011-11-10 20:37 Videos
Exit Status:  0
$

为什么是这样的表现，我怎么能解决这个问题？

Why does is behave like this, and how can i fix it?

推荐答案

在你的脚本中， SSH 工作得到相同的标准输入的阅读行，并在你的情况发生了，吃起来在第一次调用的所有行。因此，读行仅能看到
在第一行输入的。

In your script, the ssh job gets the same stdin as the read line, and in your case happens to eat up all the lines on the first invocation. So read line only gets to see the very first line of the input.

解决方案： SSH 关闭标准输入，或者更好地的/ dev / null的重定向。 （某些程序
不喜欢标准输入闭）

Solution: Close stdin for ssh, or better redirect from /dev/null. (Some programs don't like having stdin closed)

while read line
do
    ssh server somecommand </dev/null    # Redirect stdin from /dev/null
                                         # for ssh command
                                         # (Does not affect the other commands)
    printf '%s\n' "$line"
done < hosts.txt

如果您不希望从/ dev / null的重定向循环内的每一个工作，你也可以尝试下列操作之一：

If you don't want to redirect from /dev/null for every single job inside the loop, you can also try one of these:

while read line
do
  {
    commands...
  } </dev/null                           # Redirect stdin from /dev/null for all
                                         # commands inside the braces
done < hosts.txt


# In the following, let's not override the original stdin. Open hosts.txt on fd3
# instead

while read line <&3   # execute read command with fd0 (stdin) backed up from fd3
do
    commands...       # inside, you still have the original stdin
                      # (maybe the terminal) from outside, which can be practical.

done 3< hosts.txt     # make hosts.txt available as fd3 for all commands in the
                      # loop (so fd0 (stdin) will be unaffected)


# totally safe way: close fd3 for all inner commands at once

while read line <&3
do
  {
    commands...
  } 3<&-
done 3< hosts.txt

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