SSH - Autosuggestions with ZSH

A few weeks ago, I've posted a SSH - Launch a terminal on your session without having to authenticate yourself article about the ssh command in Linux.

I'm pretty sure, like me, you are tired of typing command lines like ssh christophe@1.2.3.4 to start an SSH connection because ... you know, you don't need to connect on a server; no, you need to connect to the server where the application is running; you know the name of the MyAmazingApp application but certainly not the name of the server or its IP.

That's the case for me anyway.

So, I need to connect to my vault, in which I list all the information about applications, server names, credentials to be used, ...

It would be pretty cool to run ssh MyAmazingApp no?

Two neighbours: How to connect to your hosting server using SSH to fill that ~/.ssh/config in the first place, and Master your ssh command and select the host from a list when autocompletion is no longer enough — around fifty hosts, a searchable list beats TAB.

Here's the result: type ssh (with the trailing space) and press TAB to get every alias from your ~/.ssh/config file, autosuggested.

Why It Works​

The plugin reads the Host aliases already declared in your ~/.ssh/config file and wires them into ZSH's completion system — no separate list to maintain, no vault to open, just the config file you already have.

It should be really nice to be able to run ssh MyAmazingApp and hop, I'm connected on the server.

This is where the ~/.ssh/config is so helpful (please refer to this article) but we can go one step further: it would be so great to type ssh and by some magic, Linux will show you the list of aliases defined in the ~/.ssh/config file. Let's install it.

Seeing It in Action with Docker​

No real server is ever contacted by this plugin — it only reads Host aliases from a config file — which makes it a perfectly safe one-command Docker test.

Build and run it:

$ docker build -t ssh-suggest-demo .
[+] Building 20.7s (8/8) FINISHED
✔ exporting to image
$ docker run --rm -it ssh-suggest-demo
🐳 root ~ # ssh

Type ssh (with the trailing space) and press TAB — the same four aliases from the "Use it" section below (MyAmazingApp_PROD, MyAmazingApp_TEST, YourAmazingApp, LegacyApp) show up immediately, read straight from the pre-baked ~/.ssh/config.

Installation of the zsh-ssh-config-suggestions plugin​

This assumes Oh-My-Zsh is already installed (see How to install Oh-My-ZSH if not). Just clone the official repository by running this command: git clone https://github.com/yngc0der/zsh-ssh-config-suggestions.git ${ZSH_CUSTOM:-~/.oh-my-zsh/custom}/plugins/zsh-ssh-config-suggestions. You'll get a local copy of the plugin in your Oh-my-zsh plugin folder.

Then edit the ~/.zshrc file, search for plugins=( and add zsh-ssh-config-suggestions to the list. You'll have f.i. something like:

plugins=(?
  git
  # ... your existing plugins
  zsh-ssh-config-suggestions?
)

Close your console, open a new one (or run source ~/.zshrc to load your change) and it's done.

Use it​

Imagine I've this content in my ~/.ssh/config:

Host MyAmazingApp_PROD?
    Hostname 1.2.3.4?
    User usr_app_prod?

Host MyAmazingApp_TEST?
    Hostname 6.7.8.9
    User usr_app_test

Host YourAmazingApp?
    Hostname 1.2.3.4
    User you

Host LegacyApp?
    Hostname 1.2.3.4
    User legacy

Now, I really don't need to remember anything and I don't even need to know the names of the aliases any more!

I just need to type (it's important): ssh followed by TAB and I get the same suggestions already shown at the top of this article.

As you can see, the system will display the list of hosts defined in my configuration file! I can then edit the file, add a new application and hop, next time, I'll get its name in the list. I don't need to connect to my vault anymore. Nice no?

This is just one plugin among many; if your ~/.zshrc is starting to grow with this kind of customization, have a look at Beyond the Monolith - Organizing Your ZSH Workflow Like a Pro to keep it maintainable.