Remote ssh server in shell, execute script on server

Remote ssh server in shell, execute script on server

Background : Execute pssh in shell script A, execute the script A, the process of the script A will always be stuck

Reason : pssh is a tool for executing commands on a Linux terminal in batches. After it is executed, it needs to occupy the input and output of the terminal to print the execution results. Script A itself is a process, and it also needs to occupy the input and output of the terminal to print the execution of pssh. As a result, a deadlock problem occurs, causing the process of script A to be stuck

Solution 1: Use of nohup

Use nohup将pssh挂到后台执行, that is, form a subprocess, so that script A and pssh will not seize input and output at the same time. (allip is a file whose content is the server ip that requires remote access)

#脚本作用：去到每台服务器上打印“你的大爸爸”
#!/bin/bash
echo "我来了哦"
nohup  pssh -h allip -i "echo '你的大爸爸'" > pssh.txt
cat pssh.txt

#执行结果将重定向到pssh.txt文件中，但为了能够即时显示出来，所以添加了cat pssh.txt
#"echo '你的大爸爸'"也可以替换为其他命令，只是执行后的返回信息还是会打印到pssh.txt中

#执行结果：
[root@24-78 ~]# ./pssh_shell.sh 
我来了哦
nohup: ignoring input and redirecting stderr to stdout
[1] 14:22:24 [SUCCESS] 10.10.24.81
你的大爸爸
[2] 14:22:24 [SUCCESS] 10.10.24.80
你的大爸爸
[3] 14:22:24 [SUCCESS] 10.10.24.84
你的大爸爸
[4] 14:22:24 [SUCCESS] 10.10.24.82
你的大爸爸
[5] 14:22:24 [SUCCESS] 10.10.24.83
你的大爸爸
[6] 14:22:25 [SUCCESS] 10.10.24.78
你的大爸爸
[7] 14:22:25 [SUCCESS] 10.10.24.79
你的大爸爸
[root@24-78 ~]# 

Workaround 2 : Output Redirection

The content of remote execution is between "<< EOF " and "EOF", and the operation on the remote machine is located in it. Points to note:

1. << EOF, after ssh until the end of the content such as EOF, EOF can be modified to other characters at will.
2. The purpose of redirection is not to display remote output, so that it does not preempt input and output
3. Before the end, add exit to exit the remote node

#脚本作用：去到每台服务器，执行服务器上家目录下的test.sh脚本
#!/bin/bash
IPW=$1
for i in $(cat $IPW)
do
  echo "${i}开始冲啊";
  ssh root@${i} > /dev/null 2>&1 << EOF
  ./test.sh
  exit
EOF
echo done! 
done

#执行结果
[root@24-78 ~]# ./open_test.sh allip 
10.10.24.78开始冲啊
done!
10.10.24.79开始冲啊
done!
10.10.24.80开始冲啊
done!
10.10.24.81开始冲啊
done!
10.10.24.82开始冲啊
done!
10.10.24.83开始冲啊
done!
10.10.24.84开始冲啊
done!
[root@24-78 ~]# 

#检验是否执行
#去到24.79的服务器上查看，24.79服务器上的test.sh脚本的作用是生成以当前时间命名的文件夹；
#结果如下
[root@24-79 ~]# ls
2021-09-16_1309  2021-09-16_1409  anaconda-ks.cfg  change_hostname.sh  test.sh

References:
https://blog.csdn.net/w_y_x_y/article/details/109774463
https://blog.csdn.net/xiaoxiaoonvwu/article/details/70742115