This is a bottom-up guide for installing openDCIM on a system running CentOS 6.x.

openDCIM is a free and open source solution for DataCenter Infrastructure Management. It is already used by a few organizations, and is quickly improving due to the efforts of its developers.

I have written a complete, bottom-up installation for openDCIM on CentOS. This will get you up to the first screen in the web interface, after which you can follow Scott Milliken's video tutorial for the initial settings of the application.

The guide is written for openDCIM 2.1, but should be fairly applicable to newer versions.

Read the full installation guide here.

Assuming that we have a Bash script that accepts a parameter that is expected to be an IP Address, this article lists a couple of (practically useless) ways of verifying that input without using regular expressions, which is the sane thing to do. It is therefore an exercise in futility, but it helps with my chronic allergy to regular expressions.

Από 1^η Ιανουαρίου 2013, ελευθερώνονται ως Κοινό Κτήμα (Public Domain) όλα τα έργα δημιουργών που πέθαναν το 1942.

Η σύντομη λίστα των Ελλήνων δημιουργών συμπεριλαμβάνει:

Ποιητές - Λογοτέχνες

• Λάμπρος Αστέρης (Ποιητής)
• Ιωάννης Γρυπάρης (Λογοτέχνης)
• Δημήτριος Καμπούρογλου (Ποιητής, Λογοτέχνης)
• Νικόλαος Λεβίδης (Νομικός, Συγγραφέας)
• Νικόλαος Πολίτης (Διπλωμάτης, Συγγραφέας)
• Κωνσταντίνος Ράλλης (Θεολόγος, Νομικός, Συγγραφέας)
• Ρώμος Φιλύρας (Ποιητής)

Ζωγράφοι - Γλύπτες

• Παύλος Καλλιγάς
• Γιάννης Πούλακας
• Πέτρος Ρούμπος

Μουσικοί

• Παναγιώτης Τούντας
• Γιοβάν Τσαούς

I wanted to create a fairly big MySQL database (~30GB on disk) for tests. I created a 'test' database, and a 'table2' table, with a 'content' field with datatype TEXT. Here's what I run from Bash:

marios@mysql-server:~$ time for i in `seq 1 500000`; \
do echo $i of 500000; \
mysql -u root -D test -e \
"INSERT INTO table2 (content) VALUES ('`cat /var/log/messages | tr -d \'`')"; \
done

This took a few hours to finish, while creating data at a rate of 100MBytes per minute on my test server. The size of the database was 30GB.

This did the job but it was too slow. The better way to do it, would be to run the above command for far less repetitions, say 100000, to create a smaller table, then copy that table in the same database as many times as required for the entire database to reach the desirable size, like:

create table2 like table;
insert into table2 select * from table;

You can run multiple instances of Thunderbird with different user profiles for each instance, by launching it from command line as:

[marios@bate ~]$ thunderbird -no-remote -P work &
[marios@bate ~]$ thunderbird -no-remote -P personal &

The -P option defines the profile name. If you want to create a new profile, use -P without a name.

NOTE: This article is a short version of Run multiple copies of Thunderbird at the same time from the Mozilla Knowledge Base.

Websites that use HTTP authentication, can use one of a couple of authentication methods, like Basic or Digest. When first opened, the website returns a 401 message, along with a string that contains the type of authentication and the Realm, and expects from the user to enter their credentials. Here is how to login with Python to a website that uses Digest.

• max_allowed_packet and binary log corruption in MySQL, at the MySQL Performance Blog.

Upgrade from an earlier version to 1.19.0 breaks some installations, with error:

"Revision::fetchFromConds". Database returned error "1054:
Unknown column 'rev_sha1' in 'field list' (localhost)".

This has been reported as a bug, and fixed in the development branch. Temporary fixes: downgrade back to 1.18.3 (tar.gz) or upgrade to a snapshot of the master branch of 1.20alpha.

Το εργαλείο γραμμής εντολών ifconfig μπορεί να εμφανίσει πληροφορίες σχετικά με τις διεπαφές δικτύου του συστήματος, και να κάνει ρυθμίσεις σε αυτές. Για παράδειγμα, μπορείτε να το χρησιμοποιήσετε για να δείτε την διεύθυνση MAC μιας διεπαφής, ή αν υπάρχουν συγκρούσεις πακέτων μεταξύ του συστήματος και της επόμενης συσκευής δικτύου (collissions).

Αν χρησιμοποιηθεί χωρίς καμμιά παράμετρο, απλά εμφανίζει όλες τις διεπαφές δικτύου και μερικές πληροφορίες για αυτές. Για να δείτε πληροφορίες για μια μόνο διεπαφή, δώστε το όνομά της μετά την εντολή, δηλαδή:

ifconfig eth0

Ενεργοποίηση μιας διεπαφής και ανάθεση της διεύθυνσης δικτύου 192.168.2.3/24:

ifconfig eth0 up 192.168.2.3 netmask 255.255.255.0