Run a Command That Requires sudo through SSH

Safe Shell consists of a number of tips, a lot of which may make your admin’s life exponentially simpler. One such trick is the power to run instructions on distant servers, with out logging in.

Certain, you’ll be able to take the time to log into the server, run the command, and sign off, however why not simply do it multi functional fell swoop? Not solely is that this useful, it’s fairly straightforward.

SEE: High Instructions Linux Admins Must Know (TechRepublic Premium)

What you want

The one factor you want for that is two extra Linux machines, together with the openssh-server up and operating (and accepting connections). You are able to do this from the usual repositories if you happen to don’t have the SSH daemon put in. As an illustration, on the Ubuntu Server platform, the command to put in the SSH daemon is:

sudo apt-get set up openssh-server -y

As soon as put in, you’ll need to allow the server with the instructions:

sudo systemctl begin sshd
sudo systemctl allow sshd

Word that on Ubuntu techniques, the service for the OpenSSH server is called ssh, not sshd. Subsequently, the instructions to start out and allow the SSH server could be:

sudo systemctl begin ssh
sudo systemctl allow ssh

Now that you’ve the SSH daemon operating in your distant servers, you’ll be able to ship instructions to them. Let’s learn the way.

SEE: View Your SSH Keys in Linux, macOS, and Home windows (TechRepublic)

Working a primary command

Let’s get a list of recordsdata on a distant /and many others listing. To do that, the command is:

ssh USER@SERVER_IP "ls /etc"

The place USER is a distant username, and SERVER_IP is the IP handle of the distant server. When you efficiently enter the distant person’s password, you’ll get a list of the /and many others/ listing on the distant server.

Straightforward-peasy.

SEE: Shortly Give Customers sudo Privileges in Linux (TechRepublic)

Working a command that requires sudo

However what if you should run a command that requires sudo privileges on a distant server? In the event you try this, you’ll see a tty error.

How do you get round that? Thankfully, there’s a bit of change you’ll be able to add to the command. Stated change is -t. What does -t do? It forces pseudo-terminal allocation, so ssh has no concept it doesn’t have an area terminal to make use of.

So, to run a distant command, through ssh, that requires sudo privileges, the ssh command seems to be like:

ssh -t USER@SERVER_IP "sudo COMMAND"

Say, for example, you need the person jack to improve a distant server at 192.168.1.201. This command is:

ssh -t jack@192.168.1.201 "sudo apt-get upgrade -y"

You’ll first be requested for the person’s password for the SSH connection, adopted by a second request for the person’s password for sudo privileges.

The command will run as if it was executed on the native machine (solely it’s operating on the distant machine). When the command completes, you’ll return to the native immediate, able to hold working.

And that’s all there’s to operating instructions that require sudo privileges on a distant machine, through SSH.

This text was initially revealed in July 2019. It was up to date by Antony Peyton in January 2025.