Mediawiki System Requirements

I am going to be installing Meidawiki for our internal use and I had a little trouble finding the System Requirements for the software. Just posting it here so I can find it easily again in the future.

http://www.mediawiki.org/wiki/Manual:Installation_requirements

Ghostscript Convert PDF to TIFF

Again this is mainly for my reference, but someone may have trouble finding the solution like I did earlier today.

On Windows be sure to add "C:\Program Files\gs\gs8.64\bin" to your PATH, then run the following command.

gswin32c -dNOPAUSE -q -r300 -sDEVICE=tiffg4 -dBATCH -sOutputFile=[YOUR_OUTPUT_FILENAME.TIFF] [YOUR_INPUT_FILENAME.PDF]

Similarly on Linux you can run the command below.

gs -dNOPAUSE -q -r300 -sDEVICE=tiffg4 -dBATCH -sOutputFile=[YOUR_OUTPUT_FILENAME.TIFF] [YOUR_INPUT_FILENAME.PDF]

There are also possibilities to script this, and when you can do that you should. I haven't found the need to bring it to that point yet as I just had to do four files today, but should this come up again I will be scripting it in some fashion and posting the results here.

Thank you to StackOverflow for the solution to my problem. Also one of the other solutions to this is to use a recursive search of a directory with PowerShell to convert files.

Creating a RAID 5 Array in software on CentOS 5.3

In order to create a RAID 5 array entirely in software on Linux you need to do a few things.

First I used three Identical drives, same speed, size, make, and model. This may not be a requirement, but

it will defiantly help the process. For RAID 5 you will need at least three partitions of the same size.

I picked up a four disk internal hot-swap enclosure from Addonics (http://www.addonics.com/products/raid_system/ae4rcs35nsa.asp) and

a hot-swap capable raid card. Once I got everything physically installed in the server case I booted into CentOS 5.3

and got on the command line. The first thing you need to do is create partitions on the blank drives and set them to be

Linux raid autodetect (Hex value of fd). To do this run fdisk /dev/sdX where X is the drive(s) that you want to partition for the RAID array.

For me this was SDC, SDD, SDE but you results will vary.

fdisk /dev/sdc

n [ENTER]

e [ENTER]

4 [ENTER]

[ENTER]

[ENTER]

n [ENTER]

l [ENTER]

t [ENTER]

5 [ENTER]

fd [ENTER]

w [ENTER]

You will want to create an Extended partition so choose n for New partition. If you get stuck you can hit m to get the help menu.

After you hit n type e for Extended. Then you will have to enter a partition number, I choose 4 for all of my drives.

After that you n again and then choose l for logical partition type. Again it will ask for a partition number 1-4 are for primary and thus not an option,

so I choose 5 for all of my drives.

Once the logical partitions are created hit t to change the partition type. If you are unsure what to use hit l, but in this case we already know that we want to

use type fd for the Linux RAID auto.

Once the type has been changed you can type w to write this info to the drive and start on the next one.

fdisk /dev/sdd

n [ENTER]

e [ENTER]

4 [ENTER]

[ENTER]

[ENTER]

n [ENTER]

l [ENTER]

t [ENTER]

5 [ENTER]

fd [ENTER]

w [ENTER]

fdisk /dev/sde

n [ENTER]

e [ENTER]

4 [ENTER]

[ENTER]

[ENTER]

n [ENTER]

l [ENTER]

t [ENTER]

5 [ENTER]

fd [ENTER]

w [ENTER]

Now that we have three (the minimum) partitions for our RAID device we have to create it in CentOS. Here we will use a tool called mdadm to create the

actual RAID device in Linux.

/sbin/mdadm --create --verbose /dev/md0 --level=5 --raid-devices=3 /dev/sdc5 /dev/sdd5 /dev/sde5 [ENTER]

Once this returns back, and it should be pretty quick, you will have a RAID 5 device. To check the status of it run:

/sbin/mdadm --detail /dev/md0

/dev/md0:

Version : 00.90.03

Creation Time : Wed Jul 8 09:14:19 2009

Raid Level : raid5

Array Size : 2930271744 (2794.52 GiB 3000.60 GB)

Used Dev Size : 1465135872 (1397.26 GiB 1500.30 GB)

Raid Devices : 3

Total Devices : 3

Preferred Minor : 0

Persistence : Superblock is persistent

Update Time : Fri Jul 10 11:20:02 2009

State : clean

Active Devices : 3

Working Devices : 3

Failed Devices : 0

Spare Devices : 0

Layout : left-symmetric

Chunk Size : 64K

UUID : 53f6f95a:9e33f5ba:7ac8ef3e:0a40921a

Events : 0.2

Number Major Minor RaidDevice State

0 8 21 0 active sync /dev/sdc5

1 8 37 1 active sync /dev/sdd5

2 8 53 2 active sync /dev/sde5

Now for me after I first created the RAID device the state was listed as clean, degraded, rebuilding. There was a place for the percentage rebuilt and

/dev/sde5 was listed as spare. It took the better part of a day for the rebuild to finish, given that it was a three terabyte device I am not surprised by that.

Once the rebuild was done I had to create a Physical volume for LVM to be able to manage the RAID device.

pvcreate /dev/md0

After that I was able to use system-config-lvm to create the storage volume and format the drive.

Copy Directory Structure Only

This is a simple one liner for copying a Directory structure, and not the contents.

find * -type d -exec mkdir /new_directory/\{\} \;

Now there are a few caveots to this of course, but they are simple.

First the /new_directory/ has to exist.

Second, you have to run the command from within the directory that you want to copy the structure from.

For example, if I need to copy the structure of /Storage to /newStorage I would:

mkdir /newStorage

cd /Storage

find * -type d -exec mkdir /newStorage/\{\} \;

Installing VirtualBox machine Additions on CentOS 5.1 - 5.3

For a few weeks now I have been creating a VirtualBox VM for a demo server. The purpose is to give our sales staff a way to bring our technology to the client and show them, in a live environment how our systems works, even if they don't have an Internet connection available.

I have been working on this system in a ridicously small screen for a little while now and finally got sick of it. I had tried installing the Virtual Machine additions before, but it failed for one reason or another. This time around I was determined to get everything up and running properly, so A) I wouldn't have to work on such a small screen and B) I could just move my mouse between the VM and my Desktop with out hitting a button.

Anyways, on to the meat of this, how to install the pre-requsite libraries and the Virtual Machine additons on CentOS. Now I just did this on a CentOS 5.3 install, but it has reportidly worked as far back as 5.1.

First you need to install the kernel sources and gcc, if you don't already have them.

yum isntall -y gcc
yum install -y kernel sources kernel-devel

Then you need to create a symbolic link to the kernel source:
ln -s /usr/src/kernels/2.6.18-92.1.18.el5-i686 /usr/src/linux

After this it is best to reboot the machine:
shutdown -r now

Once the machine has come back online you can mount the Guest additions ISO and install them via one of two commands depending on your architecture:

sh VBoxLinuxAdditions-x86.run

or
sh VBoxLinuxAddtions-amd64.run


After either of these commands are run you will have to once again reboot the Virtual Machine:
shutdown -r now

After the reboot you should be able to move the mouse between the VM and you Host OS without unlocking it and any of the other nifty features the Guest additions add.

Failed to modify password entry for user while adding user with smbpasswd

I was trying to create a user today in samba and was getting the error "Failed to modify password entry for user [USER]".

I read over the man pages for smbpasswd and saw that I needed to add the -n switch because this user will not have a password. So again I tried to add the user with "smbpasswd -a -n [USER]" and got the same error.

A quick Google search lead me to a newb mistake on my part... I didn't have the user I was trying to add in my UNIX password file. A quick "useradd [USER]" followed by the same "smbpasswd -a -n [USER]" and I was all set.

Granted there are other reasons why this process might fail, but for me this was the reason.

A simple file shredder for Windows

Working with sensitive data all day long you come to realize that what I download needs to be deleted securely, just as the paper copies need to destroyed securely.

I happened upon this script on Lifehacker a while ago, but I have been using it more and more lately.

First you will need to download sdelete from Microsoft. I copy this exe to the Windows directory on each machine as part of my install process.

The script if very simple:
@echo off
FOR %%F IN (%1 %2 %3 %4 %5 %6 %7 %8 %9 %10) DO sdelete -p 7 -s %%F

I save this as shred.cmd and place it in my C:\Scripts folder. It will take up to 10 files at a time and run sdelete with 7 passes on each file. Sdelete will also rename the file 26 times to obfuscate the file name.

About once a month I will run sdelete -p 3 -z to clean the free space on my PC and to make sure that any temp files I didn't shred are cleaned up. Now this won't obfuscate the file names at all, but the contents of the files are gone for good.

You can also place a short cut to the shred.cmd file into your Send To menu options and have an easy way to clean files from any folder.