Daysleeper

whose song?

“The man who sold the world” is/was basically a David Bowie song…and yes I am aware of that…since i heard it .

Kurt made it popular.

delete a file and save it in Trash

Here is a quick hackish shell script that serves as an replacement of rm command. It works on directories and files as well.

And the good thing is, when you delete your files/directories it saves it in a folder called trash and if there are duplicate stuff..then gives version to them.

#!/bin/bash
trash=$HOME"/trash"
if [ ! -n "$1" ]
    then
    echo "****** Invalid Arguments *******"
    echo "Usage: delete file/folder."
    exit 0
fi
for arg in "$@"
  do
  if [ ! -e $arg ]
      then
      continue
  fi
  file="$trash""/$arg"
  i=0
  i=`expr $i + 1`
  while true
    do
    if [ -e $file ]
    then
    file=$trash"/"$arg
    file=$file$i
    else
    mv $arg $file
      exit 0
    fi
    i=`expr $i + 1`
  done
done

Drawbacks: doesn’t work on delete style of:
del /var/www/most_important_project_evet

Get rid of those .svn directories

Well, sometimes…you need a quick script to get rid of all those .svn files in your project tree. Here is a quick hack for that. Any drawbacks?

for x in `find.|egrep '\.svn'`
do
  rm -rf "$x"
done

Emacs w3m package

w3m doesn’t come with GC library, so you must download and install it as an dependency.

If you don’t have GC, installed w3m will refuse to compile and you will be deprived from all the Emacs goodness of emacs-w3m mode.

You can download it from here:

GC home

Monads in Ruby

Monads in Ruby:

Monads in Ruby

Ruby Conf 2006

Rubyists from around the world are meeting up for RubyConf 2006, I can’t help feeling a little sad, about not being there.

No green threads in Ruby2.0

Nick Sieger has published an interview with Matz, on the eve of Rubyconf 2006.
Ruby2.0 will not have green threads and Continuations.

You can read it all by yourself here.

Where are my Programmer's manual?

Well, Ubuntu doesn’t comes bundled with Programmer’s manual pages unlike Fedora that I have used for my lifetime.

Turned out, it was really easy stuff:

#apt-cache search manpages-dev

There goes all the wise words of giants, on whose shoulders we stand.

Monit configurations files

Here are some monit configurations file that might be useful in creating monit daemons that monitor the processes:

Config file

Another config file

Continuations in Ruby

These days, you hear lots of hue and cry about and how do one go about implementing them.

First question one would ask is, “What are Continuations?”

According to WikiPedia: “In computing, a continuation is a representation of the execution state of a program (for example, the call stack or values of variables) at a certain point. Many languages have constructs that allow a programmer to save the current execution state into an object, and then restore the state from this object at a later point in time (thereby resuming its execution). This technique has been used in functional programming, imperative programming, and message passing programming.”

I hope you get that, if not then fear not continuations are basically a way of returning/saving state of methods.

How?

Let me demonstrate:

def foo; return 666; end;

So, this function returns the value to the calling function, but what if we can pass where to return the call as an argument to the method:

def foo data,cont
  cont rand(data)
end

I guess, that would be the gist of the matter, so in short an continuation never returns. Many people also like to see as gotos.
Whatever the thing:

Shamelessly stolen from ruby-docs here is the code that demonstrates continuations in Ruby:

arr = [ "Freddie", "Herbie", "Ron", "Max", "Ringo" ]
callcc{|$cc|}
puts(message = arr.shift)
$cc.call unless message =~ /Max/

So, what exactly is it doing? Well line #1, creates an array and second line creates a continuation object that can be passed around for calling a method. So, whenever you do call on a continuation object then the execution starts from the end of the block and hence you see loop here, even though none exists.