These are the individual background properties in CSS.

background-color
background-image
background-repeat
background-attachement
background-position

The background-color property specifies the color of the element. This can be useful to specify if someone has turned images off and you want a non-default view of your content. You can use a hex value (#RRGGBB), a shortcut hex value (#RGB) or a named color (red, green,blue).

background-color: #fffffff;

The background-image specifies an image to place in the background of an element. Remember that the image should be supported by as many browsers as possible. This means using jpeg, pngs or gifs, not tifs or proprietary image formats.

background-image: url(images/someimage.gif)

The background-repeat property specifies how an image should display within an element. You can have it repeat across (repeat-x), repeat downwards (repeat-y) or not repeat (no-repeat).

background-repeat: repeat-x;

The background-attachmemnt attribute is used to specify if an image should scroll (scroll) with the page, be fixed (fixed) to the page or inherit position from a parent element (inherit).

background-attachment: fixed;

The background-position attribute is used to specify the starting position of an image. This can be useful if you are using a sprite to speed up loading times. The background-position attribute can take a Xpx Ypx argument, an X% Y% argument, named arguments(left top, right bottom,…) or inherit from the parent.

background-position: 50% 50%;

Here is an example of the use of these:

 body {
   background-color: #ffffff;
   background-image: url(images/someimage.gif);
   background-repeat: no-repeat;
   background-attachment: fixed ;
   background-position: left top ;
}

You can also use a short cut method to the background property.

 .imagebox {
  background: #ffffff url(images/someimage.gif) no-repeat fixed right top;
}

Tags: CSS, html, properties

I was tracking a log file the other day and had to reload the file from disk regularly so I wanted to find out how to make a shortcut key to the Reload from disk menu entry on the File menu. Using the Settings->Shortcut Mapper to update the shortcuts for a given menu entry, I chose the Ctrl-R sequence but you are welcome to find an unmapped key sequence that works for you.

So I lost my hard drive and went to play some of the videos that I have saved on the system and could no longer play them in Windows Media Player. I needed to download a set of video codecs to play my .vob files. I am using the K-Lite Codec Pack.

Featured Software

VIDEO CODECS
FFDShow MPEG-4
DivX 8
Koepi’s XviD Codec
DScaler MPEG Filters
Ogg Codecs
Xvid Video Codec
Nic’s XviD Codec
Ligos Indeo Codec
AUDIO CODECS
MPEG Layer-3 Codec
AC3 Filter
AC-3 ACM Codec
CoreVorbis Decoder
LAME DirectShow Filter
LAME MP3 Encoder
Monkey’s Audio
Vorbis Ogg ACM Codec

This allows me to view the files in other video apps as well.

Tags: Video, Windows

I regularly have to process Comma Seperated Value or CSV files, usually for user lists. So the following perl code is a framework for processing a file line by line.

#!/usr/bin/perl
use strict;
my $line;

open(FILEIN, "filename.txt");

while(<FILEIN>)
{
  chomp();
  $line = $_;
  # Process $line for data
  # Example seperating line by commas: 
  my ($username,$firstname,$lastname,$email) = split(/,/,$line);
}

close(FILEIN);

Tags: perl, scripting

Here are some basics about Perl hashes that can be helpful to be used when an you need to associate a label with some value such as for names and telephone numbers or account numbers with amounts owed.

Create a hash variable.

my %hashvar;

Create a hash reference

my $refhash = {};

Add a value to a hash variable.

$hashvar{'somekey'} = 'someval';

Add a value to a hash reference.

$hashref->{'somekey'} = 'someotherval';

Access a value in a hash.

print $hashvar{'somekey'};

Access a value in a hash reference.

print $hashref->{'somekey}';

Access all Keys in a hash variable.
foreach my $k (keys(%hashvar))
{
print $hashvar{$k};
}

Access all Keys in a hash reference.

foreach my $k (keys(%$hashref))
{
  print $k . "n";
}

Access all Keys and values in a hash.

while (my ($key,$value) = each %hashvar)
{
  print "Key: " . $key . " has value:" . $value . "n";
}

Access all Keys and values in a hash.

while (my ($key,$value) = each %$refhash)
{
  print "Key: " . $key . " has value:" . $value . "n";
}

Assigning multiple values to a hash

%hasvar = (
  'test2' => 'myval',
  'test3' => 'myval3'
);

Note: This will clear the existing hash.

Delete a value from a hash

delete $hashvar{'key1'};

Delete a value from a hash reference.

delete $hashref->{'key1'};

Tags: hash, perl, scripting, Utilities

I was asked about system utilization on Linux systems. I found thesystatset of tools which consist of: sar, sadf, mpstat, iostat, nfsiostat, cifsiostat, pidstat and sa tools.

I will talk about the iostat tool in this article and follow up about some of the other tools.

On Ubuntu or debian systems you can install this toolset with:

sudo apt-get install sysstat

Then you will have access to the iostat command. The command output from executing with no options is below:

# iostat
Linux 2.6.32-33-generic (sumo)  09/01/2011      _i686_  (2 CPU)

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.11    0.00    0.47    0.01    0.00   99.41

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sda               0.54         1.85         8.91    1611385    7740024

This displays the avg-cpu utilization and a device usage list with basic utilization.
Some options you can use are

One more way to use the iostat tool is to specify an interval and count to the command

iostat -d -x 10 5

This will display the output 5 more times with 10 seconds between each run.

Tags: Linux, system tools, utilization

I happened to be creating a script and found myself trying to copy and past some functions between them. Well my functions
had some comments and this caused the paste operation into vi to add comments to every line after the first comment.

So this:

sub somefunc {
  # input args
  my $var1 = shift;
  my $var2 = shift;

  if ($var1 < $var2)
  {
    return $var1;
  }
  else
  {
    return $var2;
  }
}

Became this:

sub somefunc {
  # input args
  #my $var1 = shift;
  #my $var2 = shift;
  #
  #if ($var1 < $var2)
  #{
  #  return $var1;
  #}
  #else
  #{
  #  return $var2;
  #}
  #}

This made all my formatting go awry as well, and there were about 4 different functions I was about to cut and past. So I looked into how to make vi accept the text as is without adding formatting. The answer is the paste and nopaste mode.

To enter the mode to allow pasting without formatting:

:set paste

To return to regular mode:

:set nopaste

There are also ways to bind a key to more quickly enter and exit this mode if you are pasting on a regular basis.
That will be in another article.

Tags: editor, vi

If you ever need to schedule a job regularly on a Unix system, they have a great utility called cron. This will run a job at a regularly scheduled time.

Here is the format:

* * * * *  command to be executed
_ _ _ _ _ 
| | | | |
| | | | +--- day of week (0 = Sunday - 6 = Saturday)
| | | +----- month (1 - 12)
| | +------- day of month (1-31)
| +--------- hour(0-23)
+----------- minute (0-59)

example of a script that runs every day at 7:

* 7 * * * sendmeupdate

When I was trying to terminate a python script after a failure, I tried to find the nicest way to exit. The sys.exit() command provided by importing the sys library was what I found.

The function can take an optional numeric argument, usually in the range of 0-127, and with no argument it returns 0. The return code is passed back to the Operating System.

import sys
sys.exit(1)

When exit returns a non-zero value, it is considered an error.

Tags: Python

When you need to do some processing in bash and display if a file exists, the following is a simple script that takes the filename in the $testfile variable and reports if it exists or not.

if [ -f $testfile ]
then
  echo $testfile exists!
else
  echo $testfile does not exist
fi