I was writing a batch file the other day and needed to change the argumets to a command based on if the user had specified his password on the command line.

SET PASS=somepassword
: or
:SET PASS=
if x%PASS%= X (
  SET PASSARG=--password somepassword
) else
(
  SET PASSARG=
)

commandtorun %PASSARG%

Now if the user comments out his password, the script will make the PASSARG environment variable be empty or if they set a password the passarg variable will be filled in.

Tags: DOS, scripting

In each language that I have learned I have found it useful to know how to process command line arguments and here is a simple framework that I use for Java. I usually wrap the java command line in a bat or shell file to make it easier to run so that the user does not have to worry about classpath or path issues.

The following is the basic code to handle the command line arguments.

class CmdArgs
{

  public static void main(String[] args)
  {
      int argsize = args.length;
      String curarg;

      if (argsize > 0 )
      {

      }

      for(int i = 0; i < argsize; i++)
      {
          if (args[i].equals("--host")
          {
             args++;
             host = args[i];
           }
          else if (args[i].equals("--debug")
          {
               debug = 1;
          }
          else
          {
              System.out.println("Unknown option: " + args[i]);
              System.exit(1);
          }
       }

   }
}

The bat file for Dos/Windows might look like this:

@echo off

java -cp c:\javabin;somejar.jar  com.etechtips.CmdArgs %*

The shell based file might look like:

java -cp /home/ecdown/javabin:somejar.jar com.etechtips.CmdArgs $*

Tags: Java, Scripts

I use find and grep quite a bit. I found that I was regularly searching for strings in file and was typing commands like:

find . -exec grep "somestring" {} \; --print

This find command will search from the current directory and for each file will run grep on it and if it finds a matching string, it will print the string and then the filename. So I took this and moved it into a script.

#!/bin/sh

if [ $# -lt 1 ]; then
  echo 1>&2 Usage: $0 ""
  exit 127
fi
icase=
search=

while [ $# -ge 1 ]; do
  case $1 in
     -i) icase=$1;;
      *) search=$1 ;;
  esac
  shift
done

find . -type f -print0 | xargs -0 grep $icase $search

This allows me to run a command such as

efind -i Super

This command will search all files starting from the current directory and recurse directories and the “-i” will tell it to ignore case.

Tags: scripting

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

This is the correct order to place the styles in your Cascading Style Sheet(CSS) markup to style links.
The order does matter as out of order markup can lead to lost properties.

a:link {}
a:visited {}
a:focus {}
a:hover {}
a:active {}

Tags: CSS

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 use perl arrays in some of my programs, and just started to look at the regular things that I do with these arrays and thought it would be useful to keep a list of frequently used items.

Create a variable specified as an array.

my @vararray

Add an item to the beginning of an array

unshift (@vararray, "File2");

Add an item to the end of an array

push (@vararray, "File1");

Remove an item from the beginning of an array

my $var = shift(@array);

Remove an item from the end of an array

pop(@array)

Clear an array

@vararray = ();

Address an item in an array

print $vararray[0] ;

Get the size of an array

my $arraysize = @array;

Remove an item based on the index

delete @vararray[1];

Iterate over an array

foreach my $var (@vararay)
{
  print "$var \n";
}

# or
my $size = @vararray;
my $i;
for ($i = 0 ; $i < @size; $i++)
{
  print "$vararray[$i]\n";
}

Tags: array, perl, scripting

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

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