Category Archives: Linux
Splitting and catting a tar file into 2 Gb chunks
Post migrated from my old site:
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:
#!/bin/bash
Adding a disk to your logical volumes
Post migrated from my old site:
I found this information quite useful:
http://www.linuxnetadmin.com/2008/01/how-to-add-disk-space-with-lvm-on-linux.html
https://ext4.wiki.kernel.org/index.php/Frequently_Asked_Questions
Firefox fix for Fedora 12
Post migrated from my old site:
If your Firefox automatically starts offline after updating NetworkManager, you can solve this by entering
about:config
in the Firefox url bar and modify
toolkit.networkmanager.disable
to true.
Fedora – Installing VirtualBox with Yum
Post migrated from my old site:
Instructions to install VirtualBox (http://www.virtualbox.org) with Yum on Fedora can be found here:
http://www.virtualbox.org/wiki/Linux_Downloads
Debian 5 – Using the internal editor of Midnight Commander (mc)
Post migrated from my old site:
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
Post migrated from my old site:
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
Post migrated from my old site:
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
and
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
Post migrated from my old site:
To find out the user and group Apache is running under Ubuntu 10.10, look at:
/etc/apache2/envvars
Look at the lines:
export APACHE_RUN_USER export APACHE_RUN_GROUP
by default it is www-data.
Installing SugarCRM 6.0.3 on Ubuntu 10.10 Server
Post migrated from my old site:
I have been trying to set up SugarCRM 6.0.3 on a Ubuntu 10.10 VM.
This link has been very helpful:
http://g00t.com/?p=358
Another useful link is:
http://www.howtoforge.com/installing-sugarcrm-community-edition-on-ubuntu-8.10
