Saturday, November 24, 2012

A Tmux Crash Course

SkyHi @ Saturday, November 24, 2012

I’ve been using Tmux for about six months now and it has become just as essential to my workflow as vim. Pane and window management, copy-mode for navigating output, and session management make it a no-brainer for those who live in the terminal (and especially vim). I’ve compiled a list of tmux commands I use daily to help me work more efficiently.
Tmux Panes
If a tmux command I mention is bound to a keyboard shortcut by default, I’ll note that in parenthesis.


Sessions are useful for completely separating work environments. I have a ‘Work’ session and a ‘Play’ session; in ‘Work’, I keep everything open that I need during my day-to-day development, while in ‘Play’, I keep open current open-source gems or other work I hack on at home.
tmux new -s session_name
creates a new tmux session named session_name
tmux attach -t session_name
attaches to an existing tmux session named session_name
tmux switch -t session_name
switches to an existing session named session_name
tmux list-sessions
lists existing tmux sessions
tmux detach (prefix + d)
detach the currently attached session


Tmux has a tabbed interface, but it calls its tabs “Windows”. To stay organized, I rename all the windows I use; if I’m hacking on a gem, I’ll name the window that gem’s name. The same thing goes for client applications. That way, I can recognize windows by context and not what application it’s running.
tmux new-window (prefix + c)
create a new window
tmux select-window -t :0-9 (prefix + 0-9)
move to the window based on index
tmux rename-window (prefix + ,)
rename the current window


Panes take my development time from bland to awesome. They’re the reason I was able to uninstall MacVim and develop solely in iTerm2. I don’t have to switch applications to switch contexts (editing, reading logs, IRB, etc.) - everything I do, I do in a terminal now. People argue that OS X’s Cmd+Tab is just as fast, but I don’t think so.
tmux split-window (prefix + ")
splits the window into two vertical panes
tmux split-window -h (prefix + %)
splits the window into two horizontal panes
tmux swap-pane -[UDLR] (prefix + { or })
swaps pane with another in the specified direction
tmux select-pane -[UDLR]
selects the next pane in the specified direction
tmux select-pane -t :.+
selects the next pane in numerical order


tmux list-keys
lists out every bound key and the tmux command it runs
tmux list-commands
lists out every tmux command and its arguments
tmux info
lists out every session, window, pane, its pid, etc.
tmux source-file ~/.tmux.conf
reloads the current tmux configuration (based on a default tmux config)


These are some of my must-haves in my tmux config:
# remap prefix to Control + a
set -g prefix C-a
unbind C-b
bind C-a send-prefix

# force a reload of the config file
unbind r
bind r source-file ~/.tmux.conf

# quick pane cycling
unbind ^A
bind ^A select-pane -t :.+


During the day, I’ll work on one or two Rails apps, work on my dotfiles, run irssi, and maybe run vim in another window to take notes for myself. As I mentioned, I run all of this inside one tmux session (named work) and switch between the different windows throughout the day.
When I’m working on any Ruby work specifically, I’ll have a 75%/25% vertical split for vim and a terminal so I can run tests, interact with git, and code. If I run tests or ‘git diff’ and want to see more output than the 25% allots me, I’ll use tmux to swap the panes and then move into copy mode to see whatever I need to see.
Finally, I run iTerm2 in full-screen mode. Switching between OS X apps for an editor and a terminal is for chumps!