is a terminal multiplexer

it lets you switch easily between several programs in one terminal, detach them (they keep running in the background) and reattach them to a different terminal.

the benefits of using a multiplexer in the "cloud" and indeed on normal computers are pretty much self evident, so i won't repeat them here..

screen is probably still the more popular multiplexer, but its development has slowed to a crawl and its configuration is an absolute nightmare...

motivating a move from screen tmux is a bit of a tough one, the workflow is somewhat different, the default bindings are different and the initial benefits aren't immediately apparent.. however, if you've attempted to do any configuring of your screen environment or to change some of the core settings then you'll immediately appreciate the clearness and simplicity of a ~/.tmux.conf

tmux setup

current full setup is available here, but i'll run through a few of the highlights.. and some of the features which make switching from screen or in fact using tmux in general worthwhile


set -g default-shell /usr/bin/zsh
set default-path "$PWD"
set -sg escape-time 0

unbind C-b
set -g prefix C-a
bind C-a send-prefix
set -g default-terminal "screen-256color"

set-window-option -g mode-keys vi
set-window-option -g mode-mouse off

set -g history-limit 100000
set -g bell-action any
set -g display-panes-time 500
set -g set-titles on
set -g aggressive-resize on
set -g set-titles-string "tmux.#I.#W"
set -g display-time 2000

the first thing to note here is that we immediately rebind the prefix key to ^a, the tmux default is ^b as it was initially developed within a screen session.. of course, nesting tmux sessions is eminently doable, you just send two ^a 's... which is super handy if you ssh to a machine from within a session and need to pick up from where you left off on that machine..

of course, if you go down a further tmux you'll need to send four ^a 's, that is, two ^a 's to the second one down... it doesn't make much sense unless you try it in fairness, but once you get the hang of it it's super useful.. if i get around to it i'll post a gif or something..

anyway, here we've changed the prefix key and set the default-path, which ensures any new panes/windows we open are opened in our current working directory, rather than the directory the session is initially started in


set -g pane-active-border-fg blue

setw -g utf8 on

set -g status-utf8 on
set -g status-interval 10

set -g status-fg white
set -g status-bg default
set -g status-left "#[fg=colour14]#(whoami)@#h #[fg=colour11]#S#[default]"
set -g status-right "#[fg=white] #(date "+%-d/%-m/%y") #[fg=colour14]%H:%M:%S #[default]"

set -g status-left-length 100
set -g status-right-length 50
set -g message-fg white
set -g message-bg black
set -g message-attr bright

# default window title colors
set-window-option -g window-status-fg white
set-window-option -g window-status-bg default
set-window-option -g window-status-attr dim

# active window title colors
set-window-option -g window-status-current-fg colour10
set-window-option -g window-status-current-bg default
set-window-option -g window-status-current-attr dim

of course this part of the settings file isn't exactly crucial, but for me, the default look of tmux is a bit ugly.. maybe i'm being fussy, but the luminous green does nothing for me

tmux looks

a nicer statusbar and less green in general makes things a bit easier on the eye.. also, note here that the bottom right pane here contains another tmux session on another machine..


bind-key S split-window
bind-key | split-window -h

bind -r C-h select-pane -L
bind -r C-j select-pane -D
bind -r C-k select-pane -U
bind -r C-l select-pane -R

#bind C-c run "tmux save-buffer - | xclip -i -selection clipboard"

#copy tmux paste buffer to clipboard
bind C-c run "tmux show-buffer | xclip -i -selection clipboard"
#copy clipboard to tmux paste buffer and paste tmux paste buffer
bind C-v run "tmux set-buffer --- \"$(xclip -o -selection clipboard)\"; tmux paste-buffer"

bind-key 'a' last-window

bind 'h' swap-window -t -
bind 'l' swap-window -t +

bind 'j' command-prompt -p "join pane from:"  "join-pane -s '%%'"
bind 'k' command-prompt -p "send pane to:"  "join-pane -t '%%'"
bind '@' command-prompt -p "send pane to:"  "join-pane -t ':%%'"

bind 'n' next-layout

bind -r J swap-pane -D
bind -r K swap-pane -U

bind Escape copy-mode
bind -t vi-copy 'y' copy-selection

bind-key 'Space' next-window

# meta left/right cycles windows
bind-key -n M-right next
bind-key -n M-left prev

bind-key M-1 select-layout even-horizontal
bind-key M-2 select-layout even-vertical
bind-key M-3 select-layout main-horizontal
bind-key M-4 select-layout main-vertical
bind-key M-5 select-layout tiled
bind-key M-6 select-layout 3a34,279x79,0,0[279x59,0,0,279x19,0,60]

bind r source-file ~/.tmux.conf

a few bindings to make tmux more "screen"-like.. the bind -r in particular is useful, for repeatable commands, like moving around between panes.. or, as the man page says

the -r flag indicates this key may repeat

an unassorted list of nice things about tmux

anyone familiar with screen will know the basic model is something like

session -> window

so, you have a bunch of sessions, and within each session you can move around windows pretty much however you want.. this separation means that an individual screen session can crash without taking down everything, but has several notable disadvantages.. individual sessions know nothing about each other, switching between them is somewhat awkward.. for example copying/pasting stuff between sessions requires you to use an external clipboard

the tmux model however is pretty much

server -> session -> window -> pane

which initially seems a bit complicated, and it certainly takes a bit of getting used to, but it overcomes many of the annoying things about screen.. with tmux you run your sessions under a single server, this means you can easily switch sessions and send stuff around between them without having to detach and reattach

:choose-tree (only in newer versions)

^a s brings up a prompt showing your list of sessions and what's going on in them tmux here you can choose wherever you need to go


as a consequence of all the tmux sessions running under a single server your paste buffer is available everywhere, its functionality is very similar to vim buffers, which is nice..

send anything anywhere...

another consequence of the single server thing is that you can send any individual pane pretty much wherever you want, with

:join-pane -t session_name:window_number.pane_number


if you have lots of panes open, but want to do the same thing in all of them.. you can toggle this functionality on/off by doing

:set synchronize-panes

which looks a bit unwieldy, but fortunately tab-completion saves the day