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Weekly Link Dump #2

Dmytro Shteflyuk — Tue, 22 Sep 2009 13:51:04 +0000

Time to post some interesting stuff I’ve found in Internet last week. Today we going to talk about CSS font stacks, Ruby structs, extract_options! method came from Active Support, bash scripting, software version control visualization.

Guide to CSS Font Stacks: Techniques and Resources

by Cameron Chapman

CSS Font stacks are one of those things that elude a lot of designers. Many stick to the basic stacks Dreamweaver auto-recommends or go even more basic by just specifying a single web-safe font.

But doing either of those things means you’re missing out on some great typography options. Font stacks can make it possible to show at least some of your visitors your site’s typography exactly the way you intend without showing everyone else a default font. Read on for more information on using and creating effective font stacks with CSS.

When I started posting links, I decided not to mention articles posted by Smashing Magazine, thoughtbot and other sites which everyone reads. But this is totally awesome: a complete guide on font faces, list of font tools and articles about typography. I promise, I will not publish links from Smashing Magazine ever again.

Structs inside out

by Robert Klemme

Today we’re back to normal blog mode, where each article stands for itself. Muppet Labs are closed and we will be continuing our journey across the Ruby universe starting with an indepth look at Ruby’s Struct class — Ruby’s Swiss army knife for structured data.

Struct can be used without any additional require statement — it’s just there. This means it comes with zero additional overhead during initial interpreter startup — one of the many advantage of using Struct. But first let’s look at the basics.

Great Ruby Struct class usage examples.

Inside Ruby on Rails: extract_options! from Arrays

by Simone Carletti

How many times did you see a method call like the following one in your Rails application: my_method :arg1, :foo => true?

What makes my_method quite special is the ability to pass an arbitrary number of parameters (:arg1, :arg2…) followed by a list of keyword/value options.

This is made possible by a really helpful method provided by ActiveSupport called extract_options!. What this core extension does is to extract the options from the given set of arguments. When no options are available, the method returns a blank Hash.

Nice Ruby on Rails method I didn’t know.

Advanced Bash-Scripting Guide

by Mendel Cooper

The shell is a command interpreter. More than just the insulating layer between the operating system kernel and the user, it’s also a fairly powerful programming language. A shell program, called a script, is an easy-to-use tool for building applications by “gluing together” system calls, tools, utilities, and compiled binaries. Virtually the entire repertoire of UNIX commands, utilities, and tools is available for invocation by a shell script. If that were not enough, internal shell commands, such as testing and loop constructs, lend additional power and flexibility to scripts. Shell scripts are especially well suited for administrative system tasks and other routine repetitive tasks not requiring the bells and whistles of a full-blown tightly structured programming language.

Old good guide for the bash scripting. Must read for any developer.

gource — software version control visualization

by Andrew Caudwell

Gource is a software version control visualization tool for Git and CVS.

Software projects are displayed by Gource as an animated tree with the root directory of the project at its centre. Directories appear as branches with files as leaves. Developers can be seen working on the tree at the times they contributed to the project.

This freaking awesome tool produces animated visualization of source code history based on Git or CVS reporsitory. Also take a look at the code_swarm project, which does very similar things.

PS. Did you notice a new threaded comments structure in this blog? Also I have rewritten theme layout a little, so there is HTML5 here now.

[lang_ru]
ЗЗЫ. Журналисты WebStream.com.ua взяли у меня интервью. Читаем здесь.
[/lang_ru]

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How to show SSH host name on the iTerm’s background

Dmytro Shteflyuk — Fri, 01 May 2009 09:30:50 +0000

How many ssh session do you open usually? In Scribd we have about 50 machines, and most of the time I have to connect to several of them to do my work. But there is a big problem — it’s hard to distinguish among different tabs in iTerm. Of course, you can see the host where you connected to in the tab title, but the title is really small, low contrast, etc. So I had a dream since I’ve started using Mac — to get current host written with large letters on the background.

iTerm has a great support of AppleScript. Looking through the commands list I’ve found a really useful one: background image path. The last thing to figure out is how to create an image with the current host name, and I decided to use ImageMagick. So, let’s do it!

First, you need to install ImageMagick. You can use binary distribution, but I’d prefer the MacPorts version:

1	port install ImageMagick

Let’s create a test image:

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convert -size "570x342" xc:black -gravity "NorthEast" -fill "#662020" \
-family "Georgia" -style "Normal" -pointsize "60" -antialias \
-draw "text 20,10 'kpumuk.info'" "/tmp/iTermBG.png"

Here is the result and it looks pretty good!

Ok, now the most interesting part. I’ve created a bash script in ~/bin/ssh, which sets the background before calling ssh and clears it on exit. I suppose you have this folder specified before /usr/bin in your .bash_profile:

1	export PATH=$HOME/bin:/opt/local/bin:$PATH

Here is the script (the latest version could be found in a GitHub repository here):

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#!/bin/bash

# SSH with host name and IP address in background (only in iTerm.app)

# First, check to see if we have the correct terminal!
if [ "$(tty)" == 'not a tty' ] || [ "$TERM_PROGRAM" != "iTerm.app" ] ; then
/usr/bin/ssh "$@"
exit $?
fi

function __calculate_iterm_window_dimensions {
local size=( $(osascript -e "tell application "iTerm"
get bounds of window 1
end tell" | tr ',' ' ') )

local x1=${size[0]} y1=${size[1]} x2=${size[2]} y2=${size[3]}
# 15px - scrollbar width
local w=$(( $x2 - $x1 - 15 ))
# 44px - titlebar + tabs height
local h=$(( $y2 - $y1 - 44))
echo "${w}x${h}"
}

# Console dimensions
DIMENSIONS=$(__calculate_iterm_window_dimensions)

BG_COLOR="#000000" # Background color
FG_COLOR="#662020" # Foreground color
GRAVITY="NorthEast" # Text gravity (NorthWest, North, NorthEast,
# West, Center, East, SouthWest, South, SouthEast)
OFFSET1="20,10" # Text offset (host name)
OFFSET2="20,80" # Text offset (ip address)
FONT_SIZE="60" # Font size in points
FONT_STYLE="Normal" # Font style (Any, Italic, Normal, Oblique)
# Font path
FONT="$HOME/.bash/resources/SimpleLife.ttf"

HOSTNAME=`echo $@ | sed -e "s/.*@//" -e "s/ .*//"`

output=`dscacheutil -q host -a name $HOSTNAME`
RESOLVED_HOSTNAME=`echo -e "$output"|grep '^name:'|awk '{print $2}'`
RESOLVED_IP=`echo -e "$output"|grep '^ip_address:'|awk '{print $2}'`

function set_bg {
local tty=$(tty)
osascript -e "
tell application "iTerm"
repeat with theTerminal in terminals
tell theTerminal
try
tell session id "$tty"
set background image path to "$1"
end tell
on error errmesg number errn
end try
end tell
end repeat
end tell"
}

on_exit () {
if [ ! -f /tmp/iTermBG.empty.png ]; then
convert -size "$DIMENSIONS" xc:"$BG_COLOR" "/tmp/iTermBG.empty.png"
fi
set_bg "/tmp/iTermBG.empty.png"
rm "/tmp/iTermBG.$$.png"
}
trap on_exit EXIT

convert \
-size "$DIMENSIONS" xc:"$BG_COLOR" -gravity "$GRAVITY" -fill "$FG_COLOR" \
-font "$FONT" -style "$FONT_STYLE" -pointsize "$FONT_SIZE" -antialias \
-draw "text $OFFSET1 '${RESOLVED_HOSTNAME:-$HOSTNAME}'" \
-pointsize 30 -draw "text $OFFSET2 '${RESOLVED_IP:-}'" \
"/tmp/iTermBG.$$.png"
set_bg "/tmp/iTermBG.$$.png"

/usr/bin/ssh "$@"

The script is big, but very simple. In lines 6-9 script detects the current terminal application, and if it is not iTerm — skips the background generation. Also it checks if the SSH connection was requested from an interactive command line or from an another script (e.g., from git). If you want to see what host git tries to connect to — remove the tty check. Function on lines 11-22 calculates the iTerm window size, so generated background will not be stretched. If you have disabled scrollbars — remove - 15 on line 18. Configuration options determining how host name will be printed on your background are on lines 27-36. Lines 38-42 normalize host name and resolve IP address. Function on lines 44-59 changes background of the iTerm tab where ssh command was invoked from using AppleScript. It’s tricky a little, but still easy to understand. Lines 61-68 trap script exit. They handle special case when you kill ssh session, and get background image for non-ssh console. Lines 70-76 generate background image using ImageMagick.

Let’s see it in action:

So now I can stop shaking with fear when doing some destructive things in console — I know which host exactly I’m trying to kill. I hope you will find this post useful.

Changelog

05/01/2009: Updated on_exit function to fix bug with scrolling after ssh session being closed.

05/03/2009: Added some variables to customize how host name will look.

06/23/2010: Better console size detection, added normalization of host name, and IP address below the hostname, iTerm detection (to prevent errors in Terminal.app).

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