Managing Multiple Terminals with Tmux

I've started using tmux, which is a "terminal multiplexer", similar to screen. It allows you to manage a number of terminals from a single screen. So, for example, instead of having 5 PuTTY windows cluttering up your desktop, you now have only one window, containing 5 terminals. If you close this window, you can simply open a new one and "attach" to your running tmux session, to get all your terminals back at the same state you left them in.

There are lots of cool things you can do with tmux. For example, you can split a terminal window horizontally or vertically into "panes". This allows you to look at files side by side, or simply watch a process in one pane while you do something else in another.

I took the following screenshot of tmux in action:

The status bar along the bottom shows that I have 5 terminal windows open. I am currently in the one labelled "1-demo" and within this window I have 4 panes, each running a different command.

There are quite a few key bindings to learn, but once you have mastered them you will be able to jump back and forth between windows, move them around and kill them without lifting your hands off the keyboard. You can also set your own key bindings for things you do frequently. For example, my Ctrl-b / binding splits my window vertically and opens up a specified man page on the right. My Ctrl+b S binding allows me to SSH to a server in a new window.

Here is my tmux configuration taken from ~/.tmux.conf which shows my key bindings and colour setup. You can download this file from my GitHub dotfiles repository.

bind | split-window -h
bind - split-window -v
bind _ split-window -v
bind R source-file ~/.tmux.conf \; display-message "tmux.conf reloaded!"

bind / command-prompt -p "man" "split-window -h 'man %%'"
bind S command-prompt -p "ssh" "new-window -n %1 'exec ssh %1'"
bind h split-window -h  "man tmux"

set -g terminal-overrides 'xterm*:smcup@:rmcup@'

set -g history-limit 9999

# Terminal emulator window title
set -g set-titles on
set -g set-titles-string '#S:#I.#P #W'

# notifications
setw -g monitor-activity on
setw -g visual-activity on

# auto rename
setw -g automatic-rename on

# Clock
setw -g clock-mode-colour green
setw -g clock-mode-style 24

# Window status colors
setw -g window-status-bg colour235
setw -g window-status-fg colour248
setw -g window-status-alert-attr underscore
setw -g window-status-alert-bg colour235
setw -g window-status-alert-fg colour248
setw -g window-status-current-attr bright
setw -g window-status-current-bg colour235
setw -g window-status-current-fg colour248

# Message/command input colors
set -g message-bg colour240
set -g message-fg yellow
set -g message-attr bright

# Status Bar
set -g status-bg colour235
set -g status-fg colour248
set -g status-interval 1
set -g status-left '[#H]'
set -g status-right ''

set -g pane-border-fg white
set -g pane-border-bg default
set -g pane-active-border-fg white
set -g pane-active-border-bg default

Speeding up Bash Profile Load Time

I started noticing a considerable delay whenever opening a new terminal or connecting to another server. After profiling my Bash profile with a few time commands, I discovered that the slowest part was the loading of the completion file:

$ time  ~/.bash/.bash_completion

real    0m0.457s
user    0m0.183s
sys     0m0.276s

The Bash completion script I use is from http://bash-completion.alioth.debian.org. I found that there is an existing bug for this issue #467231: bash_completion is big and loads slowly; load-by-need proposed and someone has submitted a script to speed up Bash completion load time called dyncomp.sh.

This is a one-time script, which only needs to be run when you install your Bash completions or modify them. It loads your completions and moves the completion functions out of the script and into a separate directory. They are only loaded when needed. This speeds up the load time considerably and new terminal windows open up instantly!

$ time  ~/.bash/.bash_dyncompletion

real    0m0.020s
user    0m0.018s
sys     0m0.002s

You can visit my GitHub dotfiles repository for the latest version of my Bash profile.

Faster SSH with Multiplexing

OpenSSH allows you to speed up multiple SSH connections to the same server using "multiplexing". The first connection acts as the "master" and any other connections reuse the master instance's network connection rather than initiating new ones.

In order to set this up add the following to your ~/.ssh/config file:

Host *
ControlMaster auto
ControlPath /tmp/%r@%h:%p

ControlMaster auto will use a master if one exists, or start a master otherwise. ControlPath is the path to the control socket used for connection sharing. %r, %h and %p are replaced with your username, host to which you are connecting and the port respectively.

In addition, you may want to add Ciphers arcfour in order to use the arcfour cipher which is faster than the default (aes128-cbc). The transfer rate of arcfour is about 90 MB/s, aes128-cbc is about 75 MB/s and the slowest is 3des-cbc, at 19 MB/s.

Profiling Perl Code

I've started using NYTProf to profile and optimise my perl code. It produces a very useful report showing how much time is spent in each subroutine and statement.

Usage:

perl -d:NYTProf script.pl

or

perl -d:NYTProf -I/path/to/Devel-NYTProf/4.06/lib/perl5 script.pl

The output of the profiler is written to ./nytprof.out.

Use the following command to create HTML reports from the profiler's results:

/path/Devel-NYTProf/4.06/bin/nytprofhtml --file nytprof.out -out ./htmlReports --delete

Play My Code: Chain Reaction

I've just published a new game called Chain Reaction on Play My Code.

Play My Code is a place where you can create your own online games easily using the site's Quby language. The games are compiled into native JavaScript, compatible with all modern HTML5-compliant browsers. Once you've written a game, you can embed it on your website or blog, like I have done below. It's like YouTube, but for games!

Here's Chain Reaction! The aim of the game, is to start a chain reaction (by clicking on the screen) and explode as many atoms as possible. See how many levels you can complete!

Click here to see all my games.