Category Archives: Linux

Splitting and catting a tar file into 2 Gb chunks

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If you for some weird reason (which I have) would like to back large files up to a FAT32 volume and need maximum 2 Gb files, or for some other reason would like to chop up your backup file into chunks, use the following command:

tar -cvaf - *|split -b 2000m - volume.tar

To unpack use:

cat volume.tar* | tar xv

And wait a long time…

Shell scripting 101 for Linux

Post migrated from my old site:

Call me a stupid, but I always forget in what order to put the # and ! on the first line of a shell script.

So, to prevent this in the future, I will remember it here. The first line should be:


Adding a disk to your logical volumes

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I found this information quite useful:

Firefox fix for Fedora 12

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If your Firefox automatically starts offline after updating NetworkManager, you can solve this by entering


in the Firefox url bar and modify


to true.

Fedora – Installing VirtualBox with Yum

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Instructions to install VirtualBox ( with Yum on Fedora can be found here:

Debian 5 – Using the internal editor of Midnight Commander (mc)

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By default in Debian 5 mc is configuration to use nano which somehow I cannot get used to.
To fix this, go into the menu by pressing F9, Options > Configuration, Use internal edit.

Adding a Samba user

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Samba can be used to share folders with Windows systems.

To add a user to Samba, use

smbpasswd -a <username>

Setting up an encrypted RAID 5 on Ubuntu 10.10

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Recently I started on configuring an encrypted RAID 5 on Ubuntu 10.10 Server. These were the steps I took:

First, install the required packages:

sudo apt-get install mdadm gddrescue cryptsetup lvm2

I used fdisk to partition each disk as a “Linux raid autodetect” partition.

sudo fdisk /dev/sdb

for each device (in my case /dev/sdb /dev/sdc /dev/sdd and /dev/sde). First use option “n” to add a partition, option “t”to change it to type “fd” and “w” to write the changes to disk.

Next step is to create the RAID5 device:

sudo mdadm /dev/md0 --create -n 4 -l 5 -z 244198584 -c 256 /dev/sd{b..e}1

244198584 is the number of kilobyte of a single disk obtained with:

sudo hdparm -I /dev/sdb

Once it has been created, check its status by

sudo cat /proc/mdstat


sudo mdadm --detail /dev/md0

Wait until the status reports that the RAID has been fully build.

Next step is to create a physical volume by:

sudo pvcreate /dev/md0

To create a volume group, use:

sudo vgcreate rawlargevg /dev/md0

To create a logical volume, use:

sudo lvcreate -n rawsharelv -L 732585984k rawlargevg

Obtain the size by using:

sudo vgs --units k

To randomize the disk content use:

sudo ddrescue /dev/urandom /dev/rawlargevg/rawsharelv urandomminglog

This might take a long time, after it is done, start setting up the encrypted volume:

sudo cryptsetup -c aes-cbc-essiv:sha256 -y -s 256 luksFormat /dev/rawlargevg/rawsharelv

Next step is to open it:

sudo cryptsetup luksOpen /dev/rawlargevg/rawsharelv encsharedev

And format it:

sudo mkfs.ext4 -m 0 /dev/mapper/encsharedev

After it is done formatting, create a mounting directory:

sudo mkdir /srv/raid

Now edit the /etc/crypttab file to include:

encsharedev /dev/rawlargevg/rawsharelv none luks

And edit /etc/fstab to include:

/dev/mapper/encsharedev /srv/raid ext4 rw 0 0

Reboot and done you are with setting up your encrypted RAID.

References to pages I used:

User and group Apache is running under Ubuntu 10.10

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To find out the user and group Apache is running under Ubuntu 10.10, look at:


Look at the lines:


by default it is www-data.

Installing SugarCRM 6.0.3 on Ubuntu 10.10 Server

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I have been trying to set up SugarCRM 6.0.3 on a Ubuntu 10.10 VM.

This link has been very helpful:

Another useful link is: