Run a remote command using ssh config file

Question

I'd like to be able to setup a command to run on ssh login to a server, without needing to type it. Basically I'm looking for the ssh config file equivalent of:

ssh host command

so that all I need to type is:

ssh host

and the command gets run.

Answer 1

It is also possible to insert a command in your authorized keys file. (~/.ssh/authorized_keys). This allows you to execute a custom command for each key in the file. I use this to forward shell connections through my firewall. The result is that I can ssh to one host and it automatically connects the session to a host inside the network. The authorized_keys entry looks like this:

command="ssh -Tq <hostname> \"$SSH_ORIGINAL_COMMAND\"",no-port-forwarding,no-agent-forwarding,no-X11-forwarding,no-pty ssh-rsa AAAA... the rest of the key ...

More specifically the redirect is for my gitolite instance. This allows simple outside access without directly exposing the gitolite host to any external access. Check the man page for more info. ( http://linux.die.net/man/8/sshd )

Answer 2

If you are running OpenSSH, it looks like ~/.ssh/rc is executed upon login.

Answer 3

You could set up a bash alias.

In your .bashrc file, put:

alias ssl='ssh some_host run_command'

Then you wouldn't even have to type the hostname.

Or, if you wanted to do this with multiple hosts(and multiple aliases wouldn't work), then use a small script:

kevin@box:~$ cat ssl.sh
#!/bin/sh
ssh $1 some_command
kevin@box:~$

Answer 4

You cold solve this in your .ssh/config file, for the host where you want to execute a command, add

  RequestTTY yes
  RemoteCommand <some command>

where <some command> is your command. This also works with screen or tmux.