Tmux

Overview

tmux is actually a mix of screen and Gnome-Terminator. It is a terminal multiplexer: it enables a number of terminals to be created, accessed, and controlled from a single screen. Terminals can be organised in multiple panes in the same window.

Launch with

tmux                 # Start tmux (assume command 'new')
tmux attach          # Start tmux and reattach to previous session

tmux complains if it is launched as an ssh command (error not a terminal), but this is fixed with option -t:

ssh -t server tmux attach     # Launch tmux directly, require forcing terminal emulation

Useful shortcuts:

key	description
C-b " C-b % C-b o C-b C-o C-b ←|→|↑|↓ C-b Alt-←|→|↑|↓	Split horizontally Split vertically Go to next pane Go to previous active pane Go to ←, →, ↑ or ↓ pane Resize pane
C-b q	Display pane id briefly
C-b d	Detach from tmux. Reattach later with tmux attach

References

• tmux & vim (Example of .tmux.conf or [1])
• Tmux tutorial

Some cool tips on tmux. Mention plugin manager, and tmux resurrect as plugin.

• Plugin - Tmux plugin manager
• Plugin - Tmux resurrect

Tools

• Ethernal Terminal

maintains connections alive even on disconnect. Works better than autossh or mosh [2].

Byobu

Byobu is an easy-to-use wrapper around the tmux (or screen) terminal multiplexer. See Byobu page.

Tmuxinator

Install

tmuxinator is a powerful tmux session manager. It allows for saving / restoring tmux session easily.

gem install tmuxinator

Also:

• Make sure your ~/.tmux.conf DOES NOT SET base-index or pane-base-index.

# THESE MUST BE REMOVED OR COMMENTED!

# set -g base-index 1
# set-window-option -g pane-base-index 1
# set-option -g base-index 1 
# set-option -g pane-base-index 1 
# set -g pane-base-index 1 
# set-window-option -g pane-base-index 1

• Add to your ~/.bashrc. This gives access to TAB completion, and alias mux:

#### tmuxinator
[ -f /var/lib/gems/2.3.0/gems/tmuxinator-0.9.0/completion/tmuxinator.bash ] && source /var/lib/gems/2.3.0/gems/tmuxinator-0.9.0/completion/tmuxinator.bash

Usage

mux new PROJECT                               # Create a new project named PROJECT
mux start PROJECT                             # Start a project
mux PROJECT                                   # ... same
mux PROJECT ARG1 ARG2 "ARG3 with space"       # ... with arguments

Pass command-line arguments

Use Ruby ERB to pass command arguments:

name: voltron
windows:
  - madhax:
      panes:
        - gdb <% @args.each do |val| -%>"<%= val %>" <% end -%>

Capture a layout

tmux list-windows
# 1: madhax* (6 panes) [169x41] [layout 15a8,169x41,0,0{147...

Tips

Attach automatically

One can configure tmux to attach automatically to an existing session, or create one if none exists:

1. Add to ~/.tmux.conf

new-session

2. Add to ~/.bashrc

# tmux - always attach (or pass given command and parameters)
#        This solution requires to have the line "new-session" in ~/.tmux.conf
function tmux() {
    T=/usr/bin/tmux
    if [ $# -eq 0 ]; then $T attach; else $T "$@"; fi
}

Another solution (but not atomic) that does not require editing .tmux.conf is to use tmux attach || tmux new. This solutions also allows to use named sessions (see [3]).

Zoom on a pane

version 1.8 adds the zoom feature like terminator (see flag -Z to command resize-pane). Here a work-around for previous versions that binds the feature to C-b z (from [4]):

1. Edit ~/.tmux.conf

unbind z
bind z run ". ~/.tmux/zoom"

2. Edit ~/.tmux/zoom

#!/bin/bash -f
currentwindow=`tmux list-window | tr '\t' ' ' | sed -n -e '/(active)/s/^[^:]*: *\([^ ]*\) .*/\1/gp'`;
currentpane=`tmux list-panes | sed -n -e '/(active)/s/^\([^:]*\):.*/\1/gp'`;
panecount=`tmux list-panes | wc | sed -e 's/^ *//g' -e 's/ .*$//g'`;
inzoom=`echo $currentwindow | sed -n -e '/^zoom/p'`;
if [ $panecount -ne 1 ]; then
    inzoom="";
fi
if [ $inzoom ]; then
    lastpane=`echo $currentwindow | rev | cut -f 1 -d '@' | rev`;
    lastwindow=`echo $currentwindow | cut -f 2- -d '@' | rev | cut -f 2- -d '@' | rev`;
    tmux select-window -t $lastwindow;
    tmux select-pane -t $lastpane;
    tmux swap-pane -s $currentwindow;
    tmux kill-window -t $currentwindow;
else
    newwindowname=zoom@$currentwindow@$currentpane;
    tmux new-window -d -n $newwindowname;
    tmux swap-pane -s $newwindowname;
    tmux select-window -t $newwindowname;
fi

Scroll with mouse wheel

Add to ~/.tmux.conf:

#set-window-option -g mode-mouse on                  # Does not work when ssh from cygwin
set -g terminal-overrides 'xterm*:smcup@:rmcup@'

Start automatically with several command

Using cron, it is easy to launch tmux with one or several commands. Example of crontab line:

#Run both given script in separate window in the same tmux session. '-d' tells tmux to not attach to current terminal (which will fail in cron).
@reboot      /usr/bin/tmux new-session -d ~pi/bin/autonoekeon.sh \; new-window ~pi/bin/local/netconsole-log.sh

Change background color of split

tmux select-pane -t:.0 -P 'fg=blue,bg=red'

Copy session scrollback in clipboard / file

Use tmux commands

• Enter command mode with ^b :, then capture-pane -S - (since tmux 2.0), or capture-pane -S -3000.
• Save buffer with ^b : and save-buffer filename.txt.

Use custom binding

• Add to ~/.tmux.conf [5]:

bind-key P command-prompt -p 'save history to filename:' -I '~/tmux.history' 'capture-pane -S - ; save-buffer %1 ; delete-buffer'

Using standard tmux binding

• First yank the buffer with ^b [, V, gg, ^j.
• Then in same tmux, open a new windows and paste into it with ^b c, vim, :set paste, i, ^b ].

Vim-like binding for copy-paste

Add to .tmux.conf [6]:

#----------------------------------------------------------
# Vim-like copy-paste
# https://www.rushiagr.com/blog/2016/06/16/everything-you-need-to-know-about-tmux-copy-pasting-ubuntu/
# - 'Ctrl-b [' to start copy mode. 'v' to start selection, then 'y'/'enter' to yank
# - Then 'Ctrl-b P' to paste in another pane.
bind P paste-buffer
bind-key -T copy-mode-vi v send-keys -X begin-selection
bind-key -T copy-mode-vi y send-keys -X copy-selection
bind-key -T copy-mode-vi r send-keys -X rectangle-toggle

# Copy to system buffer (clipboard, but requires X fwding in ssh)
# bind-key -T copy-mode-vi Y send-keys -X copy-pipe-and-cancel "xclip -sel clip -i"

Session jumper through fzf

From here:

# Fullscreen:
bind C-j new-window -n "session-switcher" "tmux list-sessions | sed -E 's/:.*$//' | grep -v \"^$(tmux display-message -p '#S')\$\" | fzf --reverse | xargs tmux switch-client -t"
# With popup window:
bind C-j display-popup -E "tmux list-sessions | sed -E 's/:.*$//' | grep -v \"^$(tmux display-message -p '#S')\$\" | fzf --reverse | xargs tmux switch-client -t"

Troubleshoot

Not a terminal in SSH

This typically occurs when running tmux directly in ssh:

ssh server tmux

Use ssh option -t to force pseudo-TTy allocation:

ssh server -t tmux