Can anyone give an example of a command I'd want to run on every .ssh login, but not put into my .zshrc/.bashrc on that machine?

As an example: I'd love to run `set -o vi` on every ec2-user login, but the machines tend to be ephemeral and this command might not be wanted by other users, so I don't add it to /etc/profile or /etc/bashrc.

Why wouldn't you put that in ~/.bashrc ?

The ec2-user is shared by all users who might login; our EC2 hosts usually only last a few minutes/hours and are only accessed during debugging or extraordinary circumstances.

The .ssh/rc file goes on the server though, so you’d still have that problem.

What if you don't have a home directory on an ephemeral server?

Then you won’t have anywhere to store ~/.ssh/rc, and the version you’d put in /etc would still unfortunately apply to all users.

Your ssh rc is stored locally, to be executed on remote servers, right? Locally you have a home dir, but you don't on the remote.

No, it lives on the server.

allows you to use vi on the command line for anyone else who was wondering.

okay? If i'm wrong, what's it for?

It could be worded better. It allows you to use vi style keybindings when editing a line in bash. By default bash uses emacs style keybindings. It doesn't actually use vi.

thanks.

If you run a terminal multiplexer like byobu you may want to run it only for the ssh connection, not for every sub-shell (otherwise you may get a warning about running a multiplexer inside another multiplexer session).

`w` on multi-user machines that you're logging into to debug, so you can see who's on it and when they were last active.

You can automatically (re)start tmux so your sessions survive losing a connection.

You might want to curl the weather on your login with https://github.com/chubin/wttr.in I do this on my RPi

Starting a multiplexer

Notifications from sysadmin to user, reminders, and that sort of thing.

That's what /etc/motd was intended for

motd is not a per-user dynamic output though unless you put together some interesting hacks.

Do you add that on your system, and it executes the commands on all the servers you connect to?

Or do you add it to the server and they only run when you login to that server?

Looks like it executes the commands only on the server where ~/.ssh/rc or /etc/ssh/sshrc exists.

> ~/.ssh/rc

> Commands in this file are executed by ssh when the user logs in, just before the user's shell (or command) is started. See the sshd(8) manual page for more information.

You add it to the remote system.

I use it for updating a symlink in a known location to point to SSH_AUTH_SOCK. I then get tmux sessions set up to look in that location. Effectively, each time I ssh in, I fix all the ssh forwarding in active sessions (this is on local dev vagrant machines).

Whoa! Thanks for that tip, that’s an incredibly useful tip.