bootstrap CentOS from Gentoo (or any linux distribution)

To bootstrap CentOS in Gentoo, I did the following. It basically installs the essential CentOS components into the specified directory, and from there on, chroot into that directory and perform tests, etc. First off, you’ll need to unmask a few packages(replace ~amd64 with ~x86 if your on the x86 architecture), and enable the flag sqlite for rpm. Execute the following commands as root:

# echo sys-apps/yum ~amd64 >> /etc/portage/package.keywords
# echo dev-python/sqlitecachec ~amd64 >> /etc/portage/package.keywords
# echo app-arch/rpm sqlite >> /etc/portage/package.use

 
Now we’re ready to install the primary packages required to bootstrap CentOS. Merge the following atoms: sys-apps/yum app-arch/rpm dev-python/m2crypto as

# emerge -avuDN sys-apps/yum app-arch/rpm dev-python/m2crypto

 
In this example, we’ll bootstrap CentOS 5(x86_64). Download the stage2(sounds like gentoo now, huh?) from any CentOS mirror. The minimal stage2 does not work with this process.

# wget http://mirrors.seas.harvard.edu/centos/5.6/os/x86_64/images/stage2.img

 
You need to extract the contents of this squashfs image file, so make sure you have =sys-fs/squashfs-tools-3.1 installed. The latest one in portage is broken. Execute the following:

$ unsquashfs-3.1 -d /devel/centos5 stage2.img

 
Now we have a working CentOS 5.6 installation. Install bash and yum into it before you can finally chroot.

# yum --installroot /devel/centos5/ --nogpgcheck install bash
# yum --installroot /devel/centos5/ --nogpgcheck install yum

 
The –nogpgcheck is so that yum doesn’t check the gpg keys which are currently missing on your host gentoo system, or any other non-rpm distribution. chroot into /devel/centos5 and perform some cleaning:

# chroot /devel/centos5
# mkdir /old
# mv /var/lib/rpm /old
# yum install yum

 
What did you just do? Well the RPM DB generated by your host distribution’s RPM, will certainly not match CentOS’s yum, hence we remove the stale RPM database. Everything in the stage2 comprises only of the dependencies of yum and yum itself. Doing a yum install yum will fix everything.
 
Congratulations, you now have the base CentOS installation in /devel/centos5 These instructions are not limited to Gentoo alone, but to any distribution. Any questions may be posted as comments, and I’ll be glad to help you out.

/usr/local/bin/waitpid

A quick script to wait for a certain pid, then once that quits, execute a command.
You may ask, why not just do command1 && command2 ? Well, if command1 exits with a non-zero exit status value, command2 will not get executed. Hence, I’ve brewed a quick script for this purpose.

File: /usr/local/bin/waitpid

#!/bin/sh
# Find the pid of the required process either by using psaux | grep -i command
# or by pidof command
#set -x
if [ $# -ne 3 ]; then
	echo "Usage: waitpid [pid to wait for] [app name] [command]"
	echo "       [command] should be command to execute after pid is dead"
	exit 1
fi
pidr=$1
app=$2
while true; do
	pid=`pidof $app | grep -o $pidr`
	if [ "$pid" = "$pidr" ]; then
		# do nothing
		echo "pid does exist,"
		echo "waiting for 5 seconds before next check"
		sleep 5
		continue
	fi
	break
done
# if we've reached here it means that the PID is dead
echo "specified pid does NOT exist,"
echo "running command provided in 10 seconds"
echo ""
echo "Press Ctrl + c to stop"
sleep 10
$3

Coloured /var/log/messages at tty12

Reading logs could never become any more easier, at just a keystroke, you have your logs displayed where you want, in some fancy colour. They look great too.

CCZE colourized logs

TTY’s can be accessed by pressing Alt + Ctrl + F[1 – 12] simultaneously. In the following, you’ll get a decent, colourized log display of /var/log/messages when you press Alt + Ctrl + F12

First install ccze, most distributions have it in their repositories. CCZE is a robust and modular log colorizer with plugins for apm, exim, fetchmail, httpd, postfix, procmail, squid, syslog, ulogd, vsftpd, xferlog, and more. It brightens up the log view.

To quickly test it, try tail -f var/log/messages | ccze -A

The -A switch prevents ccze from starting itself in a curses window.

Create a file cclm in /usr/local/bin(you have to be root to be able to do so), with the following contents:

#!/bin/sh
file="/var/log/messages"
where="/dev/tty12"
tail -f $file | ccze -A >> $where

Add the following line to /etc/inittab
c12:123456:respawn:/sbin/agetty -n -l /usr/local/bin/cclm 38400 tty12 linux
That’s all that there is to be done, either reboot to get it working, or execute the following in a terminal with privileges:

/sbin/agetty -n -l /usr/local/bin/cclm 38400 tty12 linux

This can be used on any ttys’. The most obvious ones to use would be tty8 to tty12.

QEMU | Quick Networking for TCP/UDP

Networking with a guest in QEMU is often a headache, TUN/TAP, seriously? Too hectic, let’s stick to the basics, TCP/UDP based. Instead of setting up a really complex set of configuration files, wouldn’t it be easy to just emulate the network card, DHCP the guest, and let it work right out of the box?

Well certainly yes. QEMU can do all this very easily.

Cut the chase, hit the code:

#!/bin/sh
qemu="qemu-system-x86_64"
cpu_args="-cpu qemu64 -smp 2"
mem_args="-m 128M"
drive="-hda /media/fowlmanordisk1/devel/virtual/red.tvway"
net_args="-net user -net nic,model=rtl8139"
redirs="-redir tcp:8022::22"
${qemu} ${cpu_args} ${mem_args} ${drive} ${net_args} ${redirs} -nographic &

is one of my virtual servers’ running on Ubuntu server. Take a look at the network arguments:
-net user -net nic,model=rtl8139
Pretty simple? The QEMU emulator runs an inbuilt DHCP server, if the guest recognises the network card, and requests the configuration from the DHCP server, it acquires the required IP address, and viola! Instant access to the outside world. The file /etc/resolv.conf still needs to be configured to your preferable DNS servers. OpenDNS is usually a good solution.

Notice the -redir argument, it specifies that an issue to port 8022 on the outside be mapped to port 22 on the inside(guest). So basically you could ssh localhost -p 8022 and get access to your guest machine.

The -redir is as follows(from the QEMU manual pages):

-redir [tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport
         Redirect incoming TCP or UDP connections to the host port
         hostport to the guest IP address guestaddr on guest port
         guestport. If guestaddr is not specified, its value is x.x.x.15
         (default first address given by the built-in DHCP server). By
         specifying hostaddr, the rule can be bound to a specific host
         interface. If no connection type is set, TCP is used. This
         option can be given multiple times.

Enjoy virtual machines with QEMU.

visual basic 6 revisited – linux – wine

Earlier this year, I had written an article on running Visual Basic 6 on linux under wine, this is an update for it, the prior one is deprecated

Getting Visual Basic 6 to work on linux is pretty easy, not much trouble, all the basic things work, as of what I’ve tested.

Here’s how you get that damn thing to work:

Copy over the contents of OS/SYSTEM/ from the CD root to your wine system32 directory

$ cp -r /media/cdrom/OS/SYSTEM/* ~/.wine/drive_c/windows/system32/

Since we are only concerned about Visual Basic 6, copy over the folder VB98 from the CD root to your Program Files

$ cp -r /media/cdrom/VB98/ ~/.wine/drive_c/Program\ Files/
# for the sake of convenience, let's rename this folder as Visual Basic 6
$ mv ~/.wine/drive_c/Program\ Files/VB98/ ~/.wine/drive_c/Program\ Files/Visual\ Basic\ 6/

Register the two dynamically linked libraries essential to run Visual Basic 6 smoothly

$ cd ~/.wine/drive_c/windows/system32/
$ wine regsvr32 comcat.dll
$ wine regsvr32 MSSTDFMT.DLL

Easy, eh? Your all done, now, let’s create an optional launch command with the following contents
File: vbasic

#!/bin/bash
cd ~/.wine/drive_c/Program\ Files/Visual\ Basic\ 6/
wine VB6.EXE

Make our launcher executable and place it in the right place

$ chmod +x vbasic
# following command must be issued as root
$ mv vbasic /usr/local/bin/

Now you can just issue the command vbasic, and all should work well, using this launcher, you can create entries for your panel, etc.

Deployed with a fresh install of wine version 1.2-rc2

CPU scaling governors and you

What is your CPU being governed by? Should it be governed by it? Why? How?
Here’s an outlook on the various CPU frequency governors, namely conservative, ondemand, powersave, userspace, and performance, that steps up and steps down the CPU:
conservative
Pros:

  • very much alike the ondemand governor
  • gracefully increases the stepping, unlike ondemand which sets it to maximum when there is any load
  • more suitable for battery powered environments

ondemand
Pros:

  • the best of all
  • sets the speed to what is required
  • saves power
  • doesn’t hinder CPU power, as it scales to what is required

powersave
Pros:

  • sets the CPU statically to use the lowest possible frequency supported
  • you save power

Cons:

  • if you use resource hungry software, your machine may start to lag

userspace
Pros:

  • another application can be used to specify the frequency
  • lets you manually specify the frequency your CPU should run on

Cons:

  • mostly useless!
  • external application may set it low, you save power, but less performance
  • external application may set it high, you consume more power

performance
Pros:

  • statically sticks to the highest possible CPU scaling available, regardless of the available ones
  • your system will run as fast as possible

Cons:

  • takes the most power that you CPU is able to consume
  • not very suitable for battery powered environments, or even to save more power your machine consumes

embedded gentoo [uclibc] | nothing beats this

A few uclibc embedded gentoo facts:

  • the compilation of the box takes around 15 minutes
  • at boot up, takes less than 3 megabytes of RAM
  • disk space: 17 megabytes
  • boots in under 8 seconds on a pentium3

link to stage3 tarballs archive
HTOP - Displaying System Statistics
# this is my make.conf, it should be the same in the stage3, if installing anything in the stage3, and even before updating, comment the line INSTALL_MASK=”*.h HACKING.gz TODO.gz”

CFLAGS="-Os -mtune=i386 -pipe"
CXXFLAGS="-Os -mtune=i386 -pipe"
CHOST="i386-gentoo-linux-uclibc"

FEATURES="strip"
MAKEOPTS="-j3"
GENTOO_MIRRORS="http://mirror.bytemark.co.uk/gentoo/ http://www.ibiblio.org/pub/Linux/distributions/gentoo"

USE="-ipv6 -python3 -cracklib -minimal"

LINGUAS="en"
VIDEO_CARDS=""
ACCEPT_KEYWORDS="~x86"
INSTALL_MASK="*.h HACKING.gz TODO.gz"

# download my stage3, from the previous post links, and then prepare to chroot

mount -o bind /dev stage3-*/dev
mount -o bind /proc stage3-*/proc
chroot stage3-*

# update the system, and create the necessary path, if you come across any errors, post them here, and expect a reply soon

emerge -avuDN world
mkdir /mounted

# begin the installation
# install necessary packages

ROOT=/mounted/ emerge -auvND baselayout uclibc bash dropbear pam udev iptables coreutils nano util-linux shadow kbd net-tools grep procps gzip sed findutils mawk htop
mkdir /mounted/proc
mkdir /mounted/dev

Continue reading “embedded gentoo [uclibc] | nothing beats this”

Restore Broken Package DB on Sabayon

System database not found or corrupted, running in safe mode using temporary, empty repository

phoenix jude # equo rescue resurrect
>> ####### ATTENTION: The installed package database will be resurrected, this will take a LOT of time.
>> ####### ATTENTION: Please use this function ONLY if you are using an Entropy-aware distribution.
     Can I continue ? [Yes/No] yes
     Are you REALLY sure ? [Yes/No] yes
     Do you even know what you're doing ? [Yes/No] yes
>>  @@ Creating backup of the previous database, if exists.
>>  @@ Previous database copied to file /var/lib/entropy/client/database/amd64/equo.db.backup.15103
>>   Initializing the new database at /var/lib/entropy/client/database/amd64/equo.db
>>   Database reinitialized correctly at /var/lib/entropy/client/database/amd64/equo.db
>>   Found 420663 files on the system. Assigning packages...
>>   Matching in repository: Sabayon Linux Official Repository
>>   Found 0 packages. Filling database...
>>   Database resurrected successfully.
>>   Now generating reverse dependencies metadata...
>>   Now indexing tables...
>>   Database reinitialized successfully.
>>   Keep in mind that virtual packages couldn't be matched. They don't own any files.
phoenix jude # 

fascinating and too simple!
For one thing, I have no clue why did it say “Found 0 packages.”, because just after this I was successful in doing an equo upgrade and it worked beautifully.
equo has become a teenager…

Defining Two Different System Gateways

Situation above ground forces:
You have two modems, or two ethernet connections, and want part of your connections to go through ppp0, and the rest through ppp1

Quick Fix:
Quite easy, get both your connections live, and ppp0 will by default be the default gateway. Now, use a proxy for all other connections, so if this proxy is 10.10.1.100 on some random port, and the gateway to ppp1 is 10.6.6.6, issue the following:

route add 10.10.1.100 gw 10.6.6.6

Fedora Constantine, SYSRQ and needless swapping

By default, fedora disables the SYSRQ functionality of the kernel, for some reason. To enable it, either add sysrq_always_enabled at the end of your kernel line in /boot/grub/menu.conf, or edit /etc/sysctl.conf, changing

kernel.sysrq = 0

to

kernel.sysrq = 1

Some kernel updates on fedora also have the tendency to write to swap needlessly, even though you have loads of RAM available, to stop this, edit /etc/sysctl.conf again, and add the following two lines

# Controls the swapiness of the machine
vm/swappiness = 0

To just temporarily disable it, do

echo -n 0 > /proc/sys/vm/swappiness

as root

***These tips are applicable to almost any GNU/Linux distribution, not necessarily for Fedora alone

Visual Basic drinking Wine

This tutorial is depreciated, please follow my new tutorial: visual basic 6 revisited – linux – wine
Visual Basic running on Fedora

Get past with your life on Windows, install Microsoft Visual Basic 6 on GNU/Linux with some good old wine…

  1. Install the required libs, etc.
    $ winetricks ddr=gdi vb6run gecko gdiplus fontfix d3dx9 corefonts mdac_typ dcom98
  2. From a working Windows XP installation, copy over riched20.dll, riched32.dll, urlmon.dll, oleaut32.dll, and hhctrl.ocx, from the system32 folder to your wine system32 folder
  3. In your Wine configuration dialog, under the Libraries tab,
    set the following files to native:
    hhctrl.ocx
    oleaut32
    riched20
    riched32
    urlmon
    And set these to builtin:
    ole32
    rpcrt4
  4. Do a fresh install of IE6 with ies4linux, click on Advanced and edit the downloads and the install prefix to make it totally compatible with your existing .wine directory.
  5. Then run the Visual Basic 6 installer, and if everything goes well, cd to .wine/drive_c/windows/system32 and execute “wine regsvr32 comcat.dll” and “wine regsvr32 MSSTDFMT.DLL”

And your done! Have fun with Visual Basic on Linux!

Tested with wine 1.1.38 and Fedora Constantine(F12)

[HOWTO] Create a hidden loopback device in a .jpg file

Well, I’m sure that you are definitely curious about how do you do this. Let me tell you this, it’s really simple.
Pre-requisites:

  • Image File(any format will do or even any file will do)
  • Linux(I’ve only tested it on this platform but I guess Mac would also do)

Let’s get started, shall we?
First create a standard loopback device.

dd if=/dev/zero of=hiddenimage bs=1M count=10

Let’s see what does this do:
It creates a file called “hiddenimage”, with it’s size as 10MB.
Then, create a filesystem on it.

mkfs.ext4 hiddenimage

mke2fs 1.41.8 (11-July-2009) hiddenimage is not a block special device. Proceed anyway? (y,n) y Filesystem label= OS type: Linux Block size=1024 (log=0) Fragment size=1024 (log=0) 2560 inodes, 10240 blocks 512 blocks (5.00%) reserved for the super user First data block=1 Maximum filesystem blocks=10485760 2 block groups 8192 blocks per group, 8192 fragments per group 1280 inodes per group Superblock backups stored on blocks: 8193 Writing inode tables: done Creating journal (1024 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 39 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.

Continue reading “[HOWTO] Create a hidden loopback device in a .jpg file”

EyeCandy for your VIA Unichrome

Not until recently, did I find out about the EXA acceleration method of xorg. It’s the new acceleration architecture. Well, I tried it out, read that it had chances of decreasing the responsiveness of my computer, but hey, there’ no harm in trying it. So, got to their documentation, followed through the steps, and wow!!! The 3D graphics work very well. It didn’t even slow down my computer one bit. Let’s take it to a higher cliff this time. Installed avant-window-navigator, and that too works great. Now, even a bit higher… the compiz-fusion test. I’m not sure if compiz would work on my VIA card, with its high 3D quality, but I’m eager to try it out this evening. So, all the users still using VIA Unichrome cards, don’t give up hope! 3D does work on with the EXA acceleration. Testing will begin this evening with compiz-fusion…
Avant Navigator on my Machine
UPDATE: Running compiz results in a “White Screen”, where the cursor is available, but the rest is white. I think I’m happy with shadows, transparency, fade in/out and avant navigator.

Sabayon fOuR oH

Sabayon
Based on Gentoo,
Sabayon 4.1, tells me:

  • Great performance with less RAM(though you need like 1GB RAM for it to work well enough).
  • Package Management System is absolutely fantastic, with it’s new “Entropy”.
  • Totally the perfect distribution.
  • A fine distribution for the newbie or the expert.

This is what a critic would say:

  • Definitely better than the leading Ubuntu, like a total drift between Ubuntu and Gentoo.
  • It has many other applications that do the same thing as the main one does.

It’s an absolutely fabulous Linux Experience ever. I would rate it 9/10. Highlighting one of its features, is that all small applications can be just installed from it’s binary form, while high-end application, like openoffice, can be compiled using portage, to provide maximum efficiency. What’s more? It’s speedy and a completely out of the box experience.