How To Run Multiple SSH Command On Remote Machine And Exit Safely

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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?

There are various ways to run multiple commands on a remote Unix server. 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"

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

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.

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Historical Comment Archive

10 comment

  1. SUDO will not work inside EOF unless it is set up with the NOPASSWD option in sudoers, because your STDIN is not a standard terminal.

    The correct format would be.

    ssh server sudo -S shutdown <<EOF
    SUDOPASSWORD
    EOF
    
    -S will instruct sudo to get the password from STDIN (in this case the EOF) instead of a terminal. One disadvantage to this is your password will be captured in your session logs if it is set up. You can avoid that by running it inside a script.
  2. For SSH connections where a password is needed, use sshpass.
    For example:

    SSHPASS="password"
    SSHCOMMAND="ssh -p 22 -T -o StrictHostKeyChecking=no -o BatchMode=no"
    SSHACCOUNT="xyz@abc.com"
    
    sshpass -p "$SSHPASS" $SSHCOMMAND $SSHACCOUNT << EOF_run_commands
    uptime
    EOF_run_commands
    
  3. For more complicated tasks use Ansible.

    In fact even for non complicated tasks use Ansible; It is essentially Bash & SSH on steroids.

  4. Can I connect to multi remote host using SSH command in linux ? If not then how i connect to multi remote system using linux.?

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