Thanks for the tip. I briefly read through the docs and it's not clear what this offers above and beyond what tmux does?

The benefit of tmuxp is pretty clear from its README[1]. It gives this example:

    session_name: 4-pane-split
    windows:
    - window_name: dev window
      layout: tiled
      shell_command_before:
        - cd ~/                    # run as a first command in all panes
      panes:
        - shell_command:           # pane no. 1
            - cd /var/log          # run multiple commands in this pane
            - ls -al | grep \.log
        - echo second pane         # pane no. 2
        - echo third pane          # pane no. 3
        - echo forth pane          # pane no. 4

The example is very simple (I use tmuxp to heavily configure the session initialization), but it shows how you can have a config file to set a session's name, set the number and names of windows in there, set the layout of panes differently if you want in each window, run commands like "cd", set env vars differently if you want, in each pane.

You can find a lot more examples of tmuxp config on its doc site[2].

tmux doesn't allow one to have such quick, easy-to-read config files. You can of course do most of this in your .tmux.conf, but it will be too complicated to allow reuse and quick modifications.

[1]: https://github.com/tmux-python/tmuxp#load-a-tmux-session

[2]: https://tmuxp.git-pull.com/en/latest/examples.html

That looks handy, i can see a, 'setup my testing and development environment' with just a quick cp-and-edit of config file.

I use a shell script for such config. eg tmux split-window -h ; tmux send-keys "ls -la" C-m; ...

As I mentioned earlier, it is possible to do such things within the .tmux.conf, but not practical. Here's one of my real tmuxp configs:

    # How to use this file:
    #   tmuxp load /path/to/this/file/main.yaml
    # - Specifying the .yaml extension is optional
    # - Specifying the path is optional if file is in ~/.tmuxp
    #
    #   tmuxp --help for full help.
    session_name: main
    suppress_history: false
    start_directory: '~'
    shell_command_before:
      - unsetenv SHELL_CONFIG_LOADED
      - source ~/.alias
    windows:
      - window_name: '*scratch*'
        layout: tiled
        focus: true
        panes:
          - cd ~/downloads/git           # Top-left
          - cd ~/downloads/git/emacs     # Top-right
          - focus: true                  # Bottom-left
            shell_command:
              - bob
              - sleep 2
              - tclr                     # Clear tmux status indicators
          - shell_command:               # Bottom-right
              - cd ~/.emacs.d/elisp/org-mode
              - module load gcc/6.1.0    # Needed for ob-fortran tests to pass when doing make test for Org
      - window_name: foo-1
        layout: even-horizontal
        shell_command_before:
          - bob
          - cduh
        panes:
          - null
          - null
          - null
      - window_name: foo-2
        layout: tiled
        shell_command_before:
          - bob
          - cduh
        panes:
          - null
          - null
          - null
          - null
      - window_name: uvm_lib
        layout: tiled
        panes:
          - cd ~/gitlab/bar_uvm_lib
      - window_name: sandbox
        layout: even-horizontal
        panes:
          - null
          - null
          - null
      - window_name: hugo
        layout: tiled
        panes:
          - shell_command:
              - cd '~/downloads/git'
          - shell_command:
              - cd '~/e/elisp/ox-hugo/example-site'
              - ./srv
          - shell_command:
              - cd '~/hugo'
          - focus: true
            shell_command:
              - cd '~/e/elisp/ox-hugo'
      - window_name: nim
        layout: even-horizontal
        panes:
          - cd ~/sandbox/nim
          - cd ~/sandbox/nim
          - focus: true
            shell_command:
              - cd ~/sandbox/nim/chat
      - window_name: tok
        layout: even-horizontal
        shell_command_before:
          - tok
          - cduh
        panes:
          - null
          - null
          - null
      - window_name: zoo
        layout: even-horizontal
        shell_command_before:
          - bob
          - cduh
        panes:
          - null
          - null
          - null

I don't do it within the .tmux.conf - I use separate scripts, one per project.

I understand. But the point I am trying to make applies there too. A script to do what I am doing in the tmuxp config I last pasted would be too unmanageable, and not as readable and reusable.

I think the idea is to be able to use tmux in different layouts, configured by simple plaintext. I'll try it out.