Mosh and tmux - Remote Nivrana

Bri Hatch	Personal	Work
	bri@ifokr.org	Dropzone AI daethnir@dropzone.ai

Copyright 2024, Bri Hatch, Creative Commons BY-NC-SA License

Problem Statement

I work from many devices

• Linux desktop (standing desk)
• Mac Laptop (couch, with dogs)
• Android phone (oncall, bed)

Problem Statement

I work from many devices

• Linux desktop (standing desk)
• Mac Laptop (couch, with dogs)
• Android phone (oncall, bed)

Problem Statement (cont)

I work from many places:

• Co-work at other Droppers' houses
• Coffee shops
• Hotel on trips
• Conference Wi-fi
• Airplane Wi-fi

Problem Statement (cont)

What this means

• I'm constantly switching devices
• My connection is of varying quality
• Context switching kills productivity

My Solution

How I stay sane

• mosh - https://mosh.org/
• keep persistent connections across IP address changes and hostile wifi!
• support laggy/brittle connections
• tmux - https://github.com/tmux/tmux/wiki
• keep my tty state
• allow multiple "windows" per tty
• allow multiple "panes" per window

Mosh

Mosh is

• Fully encrypted (always)
• SSH (initially)
• UDP (thereafter)
• Framebuffer instead of stream
• <ctrl-c> more responsive
• predictive text without ACK

Mosh (cont)

Drawbacks

• requires installing mosh server and client
• no ssh port/agent/x11 forwarding
• some emojis not available 💩
• dangling mosh-server processes

Welcome to MyOS (GNU/Linux 6.8.0-45-generic x86_64)

*** System restart required ***

  You have a detached Mosh session on this server ([1228285]).

tmux

TMUX - Terminal Multiplexer

• Multiple windows in a single terminal
• Ability to disconnect / reconnect from another session
• Split window into panes
• Mouse and/or keyboard friendly usage
• Control via <ctrl-b> command or run tmux command
• Keyboard-accessible scrollback

VIM users necessity

Default prefix is <ctrl-b> which is frequently used in vim, less etc.

To use <ctrl-a> instead (screen compatible, sensible alternative)

$ cat ~/.tmux.conf

# Change the prefix key to C-a
set -g prefix C-a
unbind C-b
bind C-a send-prefix

Status bar

$ grep ^[a-z] /usr/share/dict/words | shuf | tail -5
pistachios
esthetic
loiter
tomfoolery
conjecture
$

[0] 0:DNS- 1:pulumi*                     "pulumi" 04:43 19-Apr-22

Status bar (cont)

esthetic
loiter
tomfoolery
conjecture
$ tmux set -g status-left ""
$ tmux set -g status-right "%Y-%m-%d %H:%M|#(TZ=UTC date +%%H:%%M)"
$ 

0:DNS- 1:pulumi*                            2022-04-19 04:43|11:43

• You can run commands via tmux ...
• Or via <ctrl-a>: ...
• Or put in ~/.tmux.conf

Easy to make aliases/programs that interact with tmux!

Example: Parallel Tasks

$ for host in $host_list ; do
    for container in $container_list ; do
      tmux new-window -n "$host $container" \
           ssh -ttt "$host" docker pull $container
    done
  done

0:deploy                                    2022-04-19 04:43|11:43

Example: Parallel Tasks (cont)

(0) - 0: 183 windows (attached)
(1) ├─> 0: deploy
(2) ├─> 1: prodweb-00 foo-nginx
(3) ├─> 1: prodweb-00 foo-web                            
(4) ├─> 1: prodweb-00 foo-db
(5) ├─> 1: prodweb-01 foo-nginx
(6) ├─> 1: prodweb-01 foo-web

┌────────────────────────────────────────────────────────┐
│83d624c4be2d: Already exists                            │
│1f62b39dc401: Pull complete                             │
│6c29a458e7d5: Pull complete                             │
│805908969407: Pull complete                             │
│2c1384c86539: Pull complete                             │
│b9a670e7a7f3: Pull complete                             │
│51635e63ab0c: Pull complete                             │
│57e3c615dedb: Extracting [==============>                                    ]  4.408MB/11.56MB                   │

0:deploy 1:prodweb-00 foo-nginx 2:prodweb-  2022-04-19 04:43|11:43

Starting / Connecting

• tmux list-sessions
• tmux new-session [ -t name ]
• tmux attach [-d] [-t name]
• tmux detach or
• <ctrl-a>d

Navagiting Windows

• <ctrl-a>c - new window
• <ctrl-a>0 - select window #0
• <ctrl-a>9 - select window #9
• <ctrl-a>n - next window
• <ctrl-a>' # - select window #
• <ctrl-a>w - select window from list with preview
• <ctrl-a>[ - enable keyboard scroll copy/paste mode
• <ctrl-a>, "SeaGL rocks" - rename window
• exit - close window (or pane)

Panes

• <ctrl-a>% - split horizontally
• <ctrl-a>" - split vertically
• <ctrl-a>: resize-pane -[RLDU] ### - increase pane right/left/down/up by ### chars
• <ctrl-a>: set -g mouse on] ### - enable mouse mode
• <ctrl-a>o - rotate between panes
• <ctrl-a>right/left/down/up - rotate to pane right/left/down/up

Live Demo!

Thanks!

Presentation: https://www.ifokr.org/bri/presentations/seagl-2024-mosh-and-tmux/

Personal	Work
Bri Hatch bri@ifokr.org	Bri Hatch Dropzone AI daethnir@dropzone.ai

Copyright 2024, Bri Hatch, Creative Commons BY-NC-SA License