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Steve Bennett
Asked: 2013-04-02 21:46:57 +0800 CST

Convert ssh command line arguments to .ssh/config properties

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I understand that (almost?) all SSH command line arguments can be replaced with a property in ~/.ssh/config. But it's not at all obvious how to do this systematically: the man page for ssh only refers loosely to the config page (eg, "Port forwardings can also be specified in the configuration file."). The man page for ssh_config never refers to command line options.

So, is there a definitive list of the corresponding config parameters and command line options? For example, what does -R correspond to?

ssh

2 Answers

  1. Best Answer

    Any ssh option that can be used in the form -o Option=Value can be set in the config file as an Option Value line. Many of the CLI flags are merely shorthand for long-format options, eg ssh -2 is equivalent to ssh -o Protocol=2, and can thus be set in .ssh_config as Protocol 2.

    I believe that -R x:rhost:y corresponds to RemoteForward x rhost:y.

    But I don't think there's any way to specify a flag that doesn't have a corresponding long-format form. And on my system the definitive list appears both in the ssh and ssh_config man pages, in the former under the -o flag, and in the latter in the main body of the page, starting very near the top.

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  2. -G option will display config options. This script helps to generate a clean entry from ssh command options:

    ssh2config() {
  host="$(ssh -G "$@" | sed -n 's/^hostname //p')"
  echo "$host"
  comm -23 <(ssh -G "$@" | sort) <(ssh -G abcddd | sort) | sed 's/^/    /'
  echo ''
}

    Example use:

    $ ssh2config -p 2222 me@there
there
    hostname there
    port 2222
    user me

    I have a gist that will convert your entire ssh shell history.

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