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Posts Categorized / Linux

  • Dec 07 / 2016
  • 0

Nagios plugin – Error “No such file or directory”

When trying to execute a nagios plugin, you’re getting this error:

But when checking further, the file does exist:

This can be due to some 32 bit libc libraries missing. To fix that, you will have to install the 32-bit shared libraries for AMD64 by installing this package:

And now, you can try again, error should have gone away!

  • Nov 24 / 2016
  • 0

NRPE – Enable command args (Jessie, …)

With recent versions of NRPE server, the possibility to enable command args has been disabled.

For example, on a Debian Jessie, you can get this kind of error on console:

and in logs:

!WARNING! This change can lead to security issue, this is why it has been disabled by default. You have to double check your servers can’t be reached from anywhere with NRPE commands (to avoid execution of unwanted or malicious code).

Once you’re sure there’s no security breach in your infra, you can go on with the installation of source:

Then, you’ll have to change the rules defined in the rules file:

You must add this line –enable-command-args after –libdir=/usr/lib/nagios.
You should so get something like

Finally, you can compile your new configuration and install it:

Ensure you set the value for dont_blame_nrpe in /etc/nagios/nrpe.cfg (this is the default path, it can be different depending on your installation).

And here you go, you can now restart your NRPE server and send any nrpe commands.

  • Nov 21 / 2016
  • 0

Apache – mod_auth compatibility for 2.2 and 2.4

Since Apache 2.4, mod_auth changed and some directive like

that have been replaced with

If you want to automatically handle same configuration for multiple servers where different versions of Apache are installed, you can use this trick:

Thanks to that change, your configuration will be working whatever version of Apache you’re using.

  • Oct 28 / 2016
  • 0

Add a confirmation dialog with bashAjouter une confirmation en bash

If you have a bash script doing some critical actions, it can be useful to add a confirmation dialog to double check with the user that he really wants to perform the action.

Here is a very simple script allowing this kind of checking:

Output will look like:

  • Case ‘yes’:
  • Case ‘no’:

It’s up to you customizing it depending on your needs and your feelings!Si vous avez un script bash qui exécute quelques actions critiques, il peut être utile d’ajouter une confirmation pour vérifier que l’utilisateur veut réellement exécuter l’action.

Voici un script très simple qui vous permet de faire ce type de vérification :

L’affichage ressemblera à :

  • Cas ‘yes’ :
  • Cas ‘no’ :

Libre à vous de le personnaliser selon vos besoins et vos envies !

  • Oct 19 / 2016
  • 0

Apache Tomcat – Get logs directly cleaned with rotationApache Tomcat – Nettoyer le répertoire de logs avec la rotation

Tomcat allows you to rotate easily your log files with AccessLogValve but it can be more difficult to get cleaning in logs directories automatically.

For that, you can easily use some smart find commands combined with actions:

  1. Get logs older than 3 days compressed so they can be smaller but still accessible
  2. Get logs older than 60 days deleted permanently

You will probably have to adjust the logs path depending on your needs, and you can also modify the retention time for each action.
Once the command looks correct with what you’re expecting, you can set them up as cron so it can be executed automatically every day.Tomcat vous permet d’effectuer une rotation de logs facilement avec AccessLogValve mais il peut être plus difficile de faire le nettoyage des logs du répertoire automatiquement.

Pour cela, vous pouvez facilement utiliser quelques commandes find combinées avec des actions :

  1. Compresser les logs plus vieux de 3 jours pour qu’ils prennent moins de place et soient toujours accessibles
  2. Supprimer définitivement les logs de plus de 60 jours

Vous devrez probablement ajuster le chemin des logs selon vos besoins, et vous pouvez également modifier la durée de rétention pour chaque action.
Une fois que les commandes vous semblent correctes, vous pouvez les mettre en place dans des cron de manière à les exécuter automatiquement tous les jours.

  • Oct 14 / 2016
  • 0

Generate a random file with specific sizeGénérer un fichier aléatoire d’une taille précise

It’s possible to easily generate a random file with specific size filled differently depending on the needs:

  • Fill a 200MB file with zeroes
  • Fill a 200MB file with random values (longer than zeroes – depending on processor)

Il est possible de générer un fichier aléatoire d’une taille spécifique rempli selon les besoins:

  • Remplir un fichier de 200MB avec des zéros
  • Remplir un fichier de 200MB avec des valeurs aléatoires (plus lent que des zéros – dépend de la puissance du processeur)

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