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.

`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.

Starting a multiplexer

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).

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

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

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

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).