Tmux Only For Long-Running Processes

Tmux Only For Long-Running Processes

This post describes a minimal Tmux workflow, used only for long-running processes. It is intended to reduce the cognitive load imposed by administrative debris of open tabs, panes, or windows.

Set up Tmux for a Rails project

From within a full-screen shell (to hide window chrome, status bars, notifications, the system clock, and other distractions), create a Tmux session for a Rails project:

cd project-name
tat

tat (short for “tmux attach”) is a command from thoughtbot/dotfiles that names the Tmux session after the project’s directory name. That naming convention will help us re-attach to the session later using the same tat command.

At this point, tat is the same thing as:

tmux new -s `basename $PWD`

Run the Rails app’s web and background processes with Foreman:

foreman start

The process manager is a long-running process. It is therefore a great candidate for Tmux. Run it inside Tmux, then forget it.

After only running one command inside Tmux, detach immediately:

<tmux-prefix> d

Ctrl+b is the default Tmux prefix. Many people change it to be Ctrl+a to match the API provided by GNU Screen, another popular terminal multiplexer.

Perform ad-hoc tasks

Back in a full-screen shell, we perform ad-hoc tasks such as:

vim .
git status
git add --patch
git commit --verbose

Those commands are targeted, “right now” actions. They are executed in a split second and focus us immediately on the task at hand.

Doing most of the work from inside Vim

A majority of our work is done from within a text editor, such as fast grepping in Vim:

\ string-i-am-searching-for

Or, running specs from Vim:

<Leader> s

In thoughtbot/dotfiles, <Leader> is <Space>.

Suspending the Vim process when necessary

To return control from Vim to the command line, suspend the process:

Ctrl+z

Run this command to see suspended processes for this shell session:

jobs

It will output something like:

[1]  + suspended  vim spec/models/user_spec.rb

This is when we might do some Git work:

git fetch origin
git rebase -i origin/master
git push --force origin <branch-name>
git log origin/master..<branch-name>
git diff --stat origin/master
git checkout master
git merge <branch-name> --ff-only
git push
git push origin --delete <branch-name>
git branch --delete <branch-name>

When we’re ready to edit in Vim again, we foreground the process:

fg

Re-attach to the Tmux session quickly

When we need to restart the process manager or start a new long-running process, we re-attach to the Tmux session:

tat

At this point, tat is the same thing as:

tmux attach -t `basename $PWD`

Compared to other Tmux workflows, this workflow involves more attaching and detaching from Tmux sessions. That is why the tat shortcut is valuable.

Back inside Tmux, we can kill the Foreman process:

Ctrl+c

Or, we might want to open a long-running Rails console in order to maintain a history of queries:

<tmux-prefix> c
rails console

After poking around in the database, we might detach from Tmux again:

<tmux-prefix> d

Get things done

At that point, we might take a break, go home, or move on to another project.

The next time we sit (or stand!) at our desks, we start fresh by creating a branch, opening Vim, or doing whatever ad-hoc task is necessary in a clean slate, distraction-free environment.

Meanwhile, Tmux handles one responsibility for us: quietly managing long-running processes.

Dan Croak Developer

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