I'm revisiting my working environment setup and configuration, which comprises, at its core, Bash, (Neo)vim and Tmux. This is essentially my IDE, or, to use a term I learned from TJ DeVries, my Personalised Development Environment (PDE).

Anyway, while I've used Tmux for a long time, I've never really used a plugin manager, so this week I took a look at Tmux Plugin Manager (TPM). It worked really nicely out of the box, but there were a couple of things I wanted to sort out for my particular setup.

The short video Tmux has forever changed the way I write code has a nice overview of Tmux configuration, including the use of plugins with TPM, which I'll use here as an example. The relevant configuration in tmux.conf looks like this, defining three plugins (well, two plus TPM itself):

set -g @plugin 'tmux-plugins/tpm'
set -g @plugin 'tmux-plugins/tmux-sensible'
set -g @plugin 'christoomey/vim-tmux-navigator'

run '~/.config/tmux/plugins/tpm/tpm'

The TPM command to install the plugins defined in your configuration is <prefix> I, where <prefix> is of course the Tmux prefix key, which in my case is Ctrl-space. Invoking this causes the plugins listed in the configuration to be installed, followed by status output that looks like this:

Already installed "tpm"
Installing "tmux-sensible"
  "tmux-sensible" download success
Installing "vim-tmux-navigator"
  "vim-tmux-navigator" download success

TMUX environment reloaded.

Done, press ESCAPE to continue.

Pre-installing the plugins

I don't do much at the native OS level of my laptop (which runs macOS); instead, I work in a Linux-based dev container. My PDE is essentially a Docker image, from which I create my working environment, usually just a single container, which, when it starts up, runs tmux.

So when I build my image, I'd like to have the Tmux plugins pre-installed, rather than have to go through a manual setup i.e. have to use <prefix> I when I jump into the container for the first time.

After a bit of digging, I found that I can do this by running the bin/install_plugins script which is part of TPM.

So here's a simplified extract of my dev container's Dockerfile definition (ignore the use of the root user here, this is from a testing image setup):

ARG SETUPDIR=/tmp/setup
ARG CONFDIR=/root/.config

# Basic setup
RUN mkdir $CONFDIR 
RUN mkdir $SETUPDIR

# Tmux
ARG TMUXVER=3.3a
RUN cd $SETUPDIR \
    && curl -fsSL "https://github.com/tmux/tmux/releases/download/$TMUXVER/tmux-$TMUXVER.tar.gz" \
    | tar -xzf - \
    && cd "tmux-$TMUXVER" && ./configure && make && make install

# Tmux config, including plugins
RUN mkdir $CONFDIR/tmux \
    && git clone https://github.com/tmux-plugins/tpm ~/.config/tmux/plugins/tpm
COPY tmux.conf $CONFDIR/tmux/
RUN $CONFDIR/tmux/plugins/tpm/bin/install_plugins

# Off we go
CMD ["tmux"]

My basic Tmux config is copied to the configuration directory (COPY tmux.conf $CONFDIR/tmux/) and then the TPM bin/install_plugins script is executed.

When I enter the container, and find myself in a new Tmux session (thanks to CMD ["tmux"]), all the plugins are already installed. Nice!

Invoking plugin management functions

TPM has a small number of key bindings for plugin management. The default key binding for uninstalling plugins that you've removed from the list in your configuration is <prefix> + alt + u.

My daily driver is an Apple MacBook Air. One of the (many) "interesting" features of MacBook keyboards, at least with some sort of English layout, is that you can't easily type a # character. Which is especially frustrating as a developer. To get a # character you have to use Option-3 which is frankly ridiculous, but I've got used to it over the years.

Anyway, the Option key is the Alt (or Meta) key which means that in order to use <prefix> + alt + u on this keyboard, I would have to change the terminal settings for the Option key, for it to act as a proper Alt key. But then I wouldn't be able to type # characters.

Instead, again after a bit of digging, I found that you can change these default key bindings. They're actually defined in a variables.sh file:

install_key_option="@tpm-install"
default_install_key="I"

update_key_option="@tpm-update"
default_update_key="U"

clean_key_option="@tpm-clean"
default_clean_key="M-u"

SUPPORTED_TMUX_VERSION="1.9"

DEFAULT_TPM_ENV_VAR_NAME="TMUX_PLUGIN_MANAGER_PATH"
DEFAULT_TPM_PATH="$HOME/.tmux/plugins/"

This allows me to add a line to my tmux.conf file to change the binding for the "clean" option (to uninstall plugins) to something different. I chose K for "(K)lean" (as hitting "C" after the Tmux prefix key is a common action to create a new window):

set -g @tpm-clean 'K'

Now I can uninstall plugins that I've removed from my configuration with <prefix> K. Here's an example of the uninstall status output, after I removed the line specifying the christoomey/vim-tmux-navigator plugin from my tmux.conf file and then hit <prefix> K:

Removing "vim-tmux-navigator"
  "vim-tmux-navigator" clean success

TMUX environment reloaded.

Done, press ESCAPE to continue.

The removal of this plugin was just to illustrate the mechanism; I've just been looking into this plugin and I'll be using it as it's great - especially the extremely comprehensive README!

That's neat. I'll be embracing TPM from now on.