Simple bash syntax to run multiple commands on remote machine

Simply run command2 if command1 successful on a remote host called foo:
$ ssh bar@foo "command1 && command2"
For example, run uptime and date commands on a box named ‘centos7’ as ‘vivek’ user::
ssh vivek@centos7 "uptime && date"
Sample outputs:

 18:36:17 up 1 day,  8:14,  0 users,  load average: 1.02, 1.06, 1.05
Fri Jun  7 18:36:17 IST 2019

How To Run Multiple SSH Command

Run date and hostname commands:
$ ssh user@host "date && hostname"
You can run sudo command as follows on a remote box called server1.cyberciti.biz:
$ ssh -t vivek@server1.cyberciti.biz "sudo /sbin/shutdown -h now"
And, finally:
$ ssh root@server1.cyberciti.biz "sync && sync && /sbin/shutdown -h now"

Bash here document syntax to run multiple SSH command

The here document syntax tells the shell to read input from the current source (HERE) until a line containing only word (HERE) is seen:

ssh server1 << HERE
 command1
 command2
HERE

Here is another example to run a multiple commands on a remote system:

ssh vivek@server1.cyberciti.biz << EOF
 date
 hostname
 cat /etc/resolv.conf
EOF

With sudo command type:

ssh -t vivek@server1.cyberciti.biz << EOF
 sync
 sync
 sudo /sbin/shutdown -h 0
EOF

Pipe script to a remote server

Finally, create a script called “remote-box-commands.bash” as follows on your local server:

date
hostname
cat /etc/resolv.conf

Run it as follows on a remote server called nas02nixcrafthomeserver:
$ cat remote-box-commands.bash | ssh user@nas02nixcrafthomeserver
OR
cat remote-box-commands.bash | ssh -t vivek@nas02nixcrafthomeserver

How to ssh to multiple servers and run commands

One can use simple bash for loop as follows. In this example, run uptime command on three Linux server named box1, box2, and box3:

for s in box1 box2 box3
do
   ssh vivek@${s} uptime
done

Running local bash script on remote system

Create a shell script as follows:

#!/bin/bash
# Name: test.sh 
# Purpose: Run multiple commands on a remote box 
# ----------------------------------------------------
uptime
date
whoami

Now run it as follows on host named server1.cyberciti.biz:
ssh vivek@server1.cyberciti.biz 'bash -s' < /path/to/test.sh
OR run it on four servers:

for s in server{1..4}.cyberciti.biz
do
   ssh vivek@${s} 'bash -s' < /home/vivek/bin/test.sh
done

Please note that the -t option will get rid of "Sorry, you must have a tty to run sudo/insert your-command-here" error message. You can also use pssh (parallel ssh) for executing ssh in parallel on a number of Linux/Unix/BSD servers. For more info see your ssh and bash command man page:
$ man ssh
$ man bash
$ man sudo
And there you have it, multiple bash shell command run using nothing but ssh client/sever model. A better option is to use the ansible tool.