Force SSH to use a specific shell

Solution 1:

Use a heredoc:

ssh /bin/bash << EOF
big ugly commands
lots of them

Solution 2:

I don't believe this is possible, at least with openssh-based systems. If you have the ability, a better solution might be to sftp up a shell-script file, and then execute it with the method you posted. It would have the advantage of minimizing the amount of escaping needed, but would leave a file behind that would have to be removed (perhaps as the last step of the script).

Solution 3:

Use key-based logins, not password-based. Then you can add a (list of) "forced command(s)" to your public ssh key (in the "options" field in case of SSH1) which is installed on the server (in ~/.ssh/authorized_keys file for SSH1, ~/.ssh2/authorization for SSH2).

Make your forced command so that your desired shell is called...

More: You can associate at most one forced command to a given key. If you require multiple forced commands for different purposes, you have to setup different keys. (Of course you can put multiple things into one script, which you call via forced command. But be aware that forced commands are always run for a given account/key if the user logs in, regardless if he asked for something different to run. If you want to still honor the original command asked for, have a look into how to exploit the $SSH_ORIGINAL_COMMAND variable...)

Read up about "forced commands" via Google.

Solution 4:

You can use the -t option to force allocation of a pseudo-tty for the program you want to start, as if you were executing the standard shell. Then pass the shell you want as a plain old argument.

With this technique you're able to not only use any shell that's installed but you can also open vim and other programs which require a TTY, from a single command. Which is cool if you're writing a shell script that logs you in somewhere and opens a file on vim, or htop or something.

Here's bash

me@my-machine $ ssh root@myhost -t bash

sh works too. As does anything else really.

me@my-machine $ ssh root@myhost -t sh

Not sure whether this is a login shell but there's options to make bash act like a login shell, so your shell might have that too.