How To SSH Run Multiple 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 [email protected] "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 [email protected] "command1 && command2"
Run date and hostname commands:
$ ssh [email protected] "date && hostname"
You can run sudo command as follows on a remote box called
$ ssh -t [email protected] "sudo /sbin/shutdown -h now"
And, finally:
$ ssh [email protected] "sync && sync && /sbin/shutdown -h now"

Bash here document syntax

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

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

ssh << EOF
 cat /etc/resolv.conf

With sudo command type:

ssh -t << EOF
 sudo /sbin/shutdown -h 0

Pipe script to a remote server

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

cat /etc/resolv.conf

Run it as follows on a remote server called nas02nixcrafthomeserver:
$ cat remote-box-commands.bash | ssh [email protected]
cat remote-box-commands.bash | ssh -t [email protected]

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. For more info see your ssh and bash command man page.

9 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
    -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:

    SSHCOMMAND="ssh -p 22 -T -o StrictHostKeyChecking=no -o BatchMode=no"
    SSHACCOUNT="[email protected]"
    sshpass -p "$SSHPASS" $SSHCOMMAND $SSHACCOUNT << 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.?

    1. Yes:
      ssh [email protected] ssh [email protected]

      See sshproxy for more info.

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