KDE 4.3 and Conky

While using Conky (http://korenofer.blogspot.com/2008/11/my-conky-configuration.html) with KDE 4.3 There is a background problem, instead of transparent background the Conky seems to have a black background which hide the actual desktop.
The problem is that KDE draw the wallpaper on the plasma desktop instead of the root window, When Conky try to get the background from the root window, It only get the black color.
To fix this, We can use the "feh" command which can set the background image to a specific file.
What I'm having now is the following script:
#! /bin/bash
feh --bg-scale `grep 'wallpaper=' ~/.kde/share/config/plasma-desktop-appletsrc | tail --bytes=+11`
sleep 15
conky -&

Some explanation:
The `grep 'wallpaper=' ~/.kde/share/config/plasma-desktop-appletsrc | tail --bytes=+11` command will get the current desktop picture file name.
feh --bg-scale Is used to set the background image using a file name.

And then we can call Conky (The sleep 15 is for use this script during the KDE start up,this way we make sure the desktop is up before we are trying to show the Conky output on the screen).

 

Perl inheritance - The basics

We can implement inheritance in Perl using packages (as our "classes").
The following sample will demonstrate package inheritance:

First, Lets create our base package, in this sample, I have created a simple logger package which has a constructor and a "print" method:

# Module Name
package mylogger;
## Constructor
sub new {
  print "mylogger  :new\n";
  my $package = shift;
  return bless({}, $package);
}
## Print Method
sub print
{
    print "mylogger  :print - " . $_[1] . "\n";
}
1;

If my main application will call this module:
use mylogger;
my $myLogger = mylogger->new();
$myLogger->print("Hello world");

The Ouput will be as following:
mylogger  :new
mylogger  :print - Hello world

Lets now create a newer logger which inherit the previous one and print the message time and date:
# Module Name
package newlogger;
use mylogger;
## Inherit from mylogger
our @ISA=qw(mylogger);
sub print
{
    print "newlogger :print - " . $_[1] . " (at ". localtime(time) .  ")\n";
}

Now, If we will call the new loggers following:
my $newlogger = newlogger->new();
$newlogger->print("Hello world");

The following output will appear:
mylogger  :new
newlogger :print - Hello world (at Sun Sep  6 22:00:52 2009)

OK, What happen here?
The first module is straight-forward, Please refer to my previous entry regarding Perl modules,
The second one act as following:
When newlogger->new() is being called, Perl start looking for the "new" method in the newlogger package, Since we don't have one, Perl try to look the requested method in the packages which are listed in the @ISA list.
Since we have a "new" method in our "mylogger" package, Perl call this function and do the following:
First its print the "mylogger  :new\n"  message.
Second its return a reference (by using bless) to the inserted package, which is "newlogger".

And since the "new" function returned a "newlogger" object, When the app call the $newlogger->print method, its actually calling the new method with the time stamp.

Creating and Using Perl modules

A little example to demonstrate how to create and use Perl module in Perl application.

First we will create the module:

The module file extension should be “pm”, and it should contains:
#MODULE_START
# Module Name
package Comm;
#######################################################################
## Module related arguments
use 5.006;
## Constructor
sub new {
    my $package = shift;
    return bless({}, $package);
}

#######################################################################3
## My Code
sub printHello()
{
    print "Hello World";
}

#MODULE_END

Now, Lets use the module in our Perl application
#APP_START
#/usr/bin/perl;
use strict;
use warnings;
# My Module
use Comm;

# Module creation
my $myModule= Comm->new;
$myModule->printHello;

#APP_END

Few Notes about this sample:

1. The application should know the module path.

2. As you can see, I'm calling the module function with the module prefix (Conn->....), To avoid it we can use the “Exporter” inside the module to export its function directly,

keys functions issue with VMware 6.5

Since I installed VMware 6.5 workstation on my Fedora 10 host, None of the following keys worked:

• Arrow keys
• Home
• End
• Page down/UP
• Insert
• Delete

Some keys didn't worked at all while others was mapped to wrong function (e.g. : arrow up opened the "save screenshot" dialog.

I have tried several solution (xorg.conf, evdev driver ) with no use, Till I found the following (simple) solution:

echo "xkeymap.nokeycodeMap = true" >> ~/.vmware/config

And thats it, No more keys issue :-)

Simple UDP port scanner in perl - ICMP unreachable

One way to scan the open UDP ports on a remote machine, Is to send an UDP packets to its ports and listen the ICMP "destination unreachable" responses, If we received that message, its mean that the port we have tried to send to is currently close.


In the following Perl code I will send an UDP packet to each port, and if I won't receive the ICMP destination unreachable packet I will assume the scanned port is open:

#!/usr/bin/perl

use Net::Ping;
use IO::Select;
use IO::Socket::INET;

# IP address to scan
my $ip = '10.0.0.1';

# First we will send a ping to make sure the scanned host is exist
my $p = Net::Ping->new( "icmp", 1, 64 );
if ( $p->ping($ip) ) {
 print "$ip answered ping , Start scanning ....\n";
} else {
 print "$ip did not answer ping\n";
exit 5;
}
# Time  to wait for the "destination unreachable" package.
my $icmp_timeout=2;
# Create the icmp socket for the "destination unreachable" packages  
$icmp_sock = new IO::Socket::INET(Proto=>"icmp");
$read_set = new IO::Select();
$read_set->add($icmp_sock);

# Buffer to send via UDP
my $buf="hello";

# Scan all the ports .....
for ( $i=1 ; $i <= 65535 ; $i++ ) {      # Create UDP socket to the remote  host and port    
    my $sock = new IO::Socket::INET(PeerAddr=>$ip,
    PeerPort=>$i,
    Proto=>"udp");
      # Send the buffer and close the UDP socket.
    $sock->send("$buf");
    close($sock);

      # Wait for incoming packets.
    ($new_readable) = IO::Select->select($read_set, undef, undef, $icmp_timeout);
      # Set the arrival flag.
    $icmp_arrived = 0;
      # For every socket we had received packets (In our case only one - icmp_socket)
    foreach $socket (@$new_readable)
    {
           # If we have captured an icmp packages, Its probably "destination unreachable"
         if ($socket == $icmp_sock)
         {
                # Set the flag and clean the socket buffers
              $icmp_arrived = 1;
              $icmp_sock->recv($buffer,50,0);
         }
    }
    if ( $icmp_arrived == 0 )
    {
         print "Open  UDP port : $i\n";
    }
}
# Close the icmp sock
close($icmp_sock);
print "End !!\n";

Perl - simple log-filter script

Lets say we are having a log file in the following format (/var/log/messages format):
Jan 25 00:08:33 localhost kernel: imklog 3.21.9, log source = /proc/kmsg started.
Jan 25 00:08:33 localhost rsyslogd: [origin software="rsyslogd" swVersion="3.21.9" ] restart

Here how to write a simple perl script which will print the log file using a filter (in this sample I will filter the file by its modules : kernel, rsyslogd).

Script start:

#!/usr/bin/perl

# Log file name
$FILE_NAME="messages.txt";

sub read_from_file()
{
# The first (and only) parameter in the module filter string
$MODULE_FILTER=$_[0];

# Open the file for reading, if cannot - exit
open (FHANDLE, "< ${FILE_NAME} ") || die "couldn't open the ${FILE_NAME} file!";

# Reading the file
while ()
{
# Parse the line into its parts using regular expressions
($date,$hostname,$module,$msg) = /^(.+?\s.+?\s.+?\s)(.+?\s)(.+?:\s)(.*)/;
# If ((the filter is not "ANY") and ( current line do not match the filter, in this sample - ignore case)) skip current line
unless (( ${MODULE_FILTER} eq "ANY" ) || ( ${module} =~ /${MODULE_FILTER}/i ))
{
next;
}
# print current line
print $_;
}
# close file handle
close ${FHANDLE}
}

##########################################################
## Main
#&read_from_file("ANY");
#&read_from_file("KERNEL");
Script End;

If I'm calling the subroutine with the "ALL" filter, I will see all the file.
If I will call with the "KERNEL" filter, I will only see the first line.

Building Fedora 10 kernel

Preaparing the build environment:
In order to create the file system environment we need to run the following command where we want to build the kernel (If missing, install package rpmdevtools):
#/usr/bin/rpmdev-setuptree

Now, We are having the rpmbuild directory which contain the following directories : BUILD, RPMS, SOURCES, SPECS and SRPMS.

Note: the rpmdevtools was changed between fedora 9 and 10, in 9 we had to call fedora-buildrpmtree.
Other note: Some of the operations required root permissions, you can run it
as root or use "su", just remember that the rpmbuild directory is expected in the current user home directory and pay attention to the directory permission.

To set the build in a specific path (e.g. ~/rpmbuild) add the following to the ~/.rpmmacros file:
%_topdir %(echo $HOME)/rpmbuild #path to your custom
build dir

Download and install the kernel source:
Now, we should downoad the kernel source from http://kojipkgs.fedoraproject.org/packages/kernel, since my kernel version is 2.6.27.9-159.fc10.i686 I will download the file kernel-2.6.27.9-159.fc10.src.rpm

After the download completed, extract the rpm by typing (you can ignore the "warning: group mockbuild does not exist - using root" messages):
#rpm -ivh kernel-2.6.27.9-159.fc10.src.rpm

Preparing the build (in my case, for i686):
#cd rpmbuild/SPECS
#rpmbuild -bp --target=i686 kernel.spec

Building the kernel rpm:
Note: For this sample, I will build the kernel without any configuration changes.

Go to the build directory and start the rpm build.
#cd rpmbuild/BUILD/kernel-2.6.27/linux-2.6.27.i686
#make rpm
This is going to take some time .....

Creating the ram disk:
initrd image creation:
Since the mkinitrd function searching the built modules under /lib/modules/, I created a soft link from there to the place we have built the modules
(there must be more elegant way ...)
#cd /lib/modules/
# ln -s <build path>/rpmbuild/BUILDROOT/kernel-2.6.27.9-1.i386/lib/modules/2.6.27.9 2.6.27.9
#cd <build path>/rpmbuild/BUILDROOT/kernel-.6.27.9-1.i386/boot
#mkinitrd /boot/initrd-2.6.27.9.img 2.6.27.9

Installing the new kernel:
Now, We need to copy the generated files from the <build path>rpmbuild/BUILDROOT/kernel-2.6.27.9-1.i386/boot
directory to the /boot directory in the target machine:
initrd-2.6.27.9.img,System.map-2.6.27.9,vmlinuz-2.6.27.9,config-2.6.27.9

In the /etc/grub.conf file we need to add an entry for the new kernel:
title myBuild (2.6.27.9)
root (hd0,0)
kernel /boot/ofer/vmlinuz-2.6.27.9 ro root=UUID=<your uuid> rhgb quiet
initrd /boot/ofer/initrd-2.6.27.9.img

Reboot the machine, choose the new kernel in the grub screen, and that it :-)

vmware tools for fedora 10

The vmware tools (VmwareTools-6.5.0-118166) installation went surprisingly fast (including the kernel modules compilation using vmware-config-tools.pl script) on the fedora 10 kernel version 2.6.27.9-159.fc10.i686 except two issues:


During the X server configuration, I received an error which indicate that the vmware tools cannot locate the monitor, its seems like vmware looking for Xorg instead of Xfree86.
In order to bypass this issue we should create the following /etc/X11/xorg.conf (as root):
Section "Monitor"
Identifier "vmware"
EndSection
And re-run the config tool.

The second problem was the “drug-and-drop”, IT DIDN'T WORK !!!, to fix it call /usr/bin/vmware-user as written in “http://www.virtuatopia.com/index.php/Understanding_and_Installing_VMware_Tools:
"You will need to either manually start /usr/bin/vmware-user or log out and log
back in to this desktop session to obtain the following features: guest
resolution fit, drag and drop, and file and text copy/paste. vmware-user is
configured to automatically start at a graphical login, but that won't take
effect until the next login."


If needed, Call the vmware-user every login using the application start-up list.

Activate conky upon startup

While using conky we can make it start with our system, The easiest way is to add it to the session.

Go to : System > Preferences > Personal -> Sessions -> “Startup Programs” , and add the conky to the additional startup progam list.

After the X server start, You will see something weird, the conky appear on the screen and then disappear under the background image, The problem is that the conky is starting to fast before the rest of the desktop component.

In order to fix it we will “tell” the conky to wait a while before starting ,create the following bash script conky_start:
#!/bin/bash
sleep 10
conky &
exit 0

Change it permission to execute:
#chmod 755 /usr/bin/conky_start

Try to launch it manually to make sure you don't have any typo and change the session startup-programs to launch this script instead of conky.