How To Run Multiple SSH Command On Remote Machine And Exit Safely nixCraft Updated Tutorials/Posts

I have a backup sync program on local server. I have an ssh password less login set up, and I can run commands on an external server in bash script doing:
ssh root@server2 "sync; sync; /sbin/shutdown -h now"
How do I run multiple commands in bash on a remote Unix or Linux server? What is the best way to SSH in and run various unix commands in a bash shell?

[donotprint][/donotprint]There are various ways to run multiple commands on a remote Unix server. This page show the easiest way to ssh and run multiple commands in using bash shell. The syntax is as follows.

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"
How To Run Multiple SSH Command On Remote Linux or Unix Machine

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.

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.

Posted by Web Monkey

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