SQL*Plus on Debian

In this article, I will describe the steps necessary to install Oracle SQL*Plus on a Debian host. I am using Debian 6.0.5 and will install the “Instant Client” package from Oracle (version 11.2.0.3). First, we will prepare the system for the installation, download the installation package, set all the necessary variables, start SQL*Plus and connect to an instance. So let’s get started…

Read the rest of this entry »

Debian: Script for SFTP users

When using a server with multiple external users, one thing that regularly comes up is that users want to access a folder on the server, such as the root folder for a webserver. This way every user can manage their files and upload new content. This can be achieved securely with SFTP, which uses the SSH protocol for file transfers.

In this article, I provide a simple script to create new users with minimal preparation and all correct settings. The text is based on the following article on debian-administration.org: OpenSSH SFTP chroot() with ChrootDirectory.

Read the rest of this entry »

Linux LVM How-to: Adding a new partition

Since I started out with Linux (so about six years ago), I always used the Linux Logical Volume Manager (LVM) to partition my tables. First it was just because it seemed easier to configure my harddisks with it (also, the installer usually provided a nice option to do so), but in the last few months I had the possibility to work more with LVM and got to know some nice features.

One thing I regularly have to do is to extend an existing logical volume on a server. This article focuses on extending a logical volume with the help of LVM.
Read the rest of this entry »

BASH: here-document at line n delimited by end-of-file (wanted `EOF’)

On one of our Debian hosts, we use bash scripts and cron jobs to automate certain tasks. One of these bash scripts downloads files from an FTP server and archives them. After upgrading the host machine to Debian 6.0.4, one of the bash scripts suddenly showed warnings:

/srv/foo/bar.sh: line 146: warning: here-document at line 140 delimited by end-of-file (wanted `EOF')

Read the rest of this entry »

Nagios – Error: Could not stat() command file

So there I was. I just installed Nagios on a brand new Debian (6.0.3) host, I was greeted with the following error message after logging into the Nagios web interface and clicking a link that uses external commands:

Error: Could not stat() command file ‘/var/lib/nagios3/rw/nagios.cmd’

What? Well, after making sure my configuration is correct, I figured that this must be some kind of permission problem… Read the rest of this entry »

Linux RAMDISK with tmpfs

The Linux kernel provides the tmpfs, which basically creates a file system in memory. This temporary file system can be used to store temporary data, such as caches or log files. Read more about tmpfs in the kernel documentation: tmpfs.txt

After reading this excellent article about using tmpfs in Linux, I decided to put it to the test. Even though the Linux kernel already does a good job caching files, I wanted to see the performance of this solution by applying different loads on it. For this, I am using the IOzone tool I already used for my ZFS tests (1) (2) and my Amazon EC2 IO test.

Read the rest of this entry »

Debian with a vanilla kernel

So one might want to ask why you’d want to sacrifice the fantastic stability and openness of Debian to install a vanilla (= original) kernel (Debian currently has 2.6.32). There are quite a few reasons for doing so. For example, the current kernel (2.6.38) has TRIM support, which is something I am looking for when using SSDs. Also, maybe you want to have a bleeding edge kernel just for the fun of it. So lets get started.

Read the rest of this entry »