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Lenovo E145: Backlight

Symptoms

The backlight brightness of an Lenovo E145 laptop with a Radeon HD 8240 graphics controller can not be adjusted on Debian. Neither the Fn-F7/Fn-F8 keys are working nor any other interface.

Solution

Force the use of the kernel Radeon driver by installing the (non-free) Radeon firmware.

Background

There are several drivers that may be used by the Linux kernel and the X Windows System. The trick is forcing the correct one, as not all drivers support the backlight.

MySQL: Stored programs quick reference

This is a quick reference guide for writing MySQL stored programs. It is assumed you have some experience with similar programming languages (for example, Oracle PL/SQL). This has been written for MySQL 5.6.

Defining stored programs

There are four kinds of stored programs:

  • Procedures
  • Functions
  • Triggers
  • Events

Functions can be called from SQL queries.

Openconnect: using your own DNS

Symptoms

After setting up a VPN using Openconnect, local sites stop resolving.

Solution

Stop using the DNS server belonging to the VPN; instead, use your own DNS server and hardcode servers you want to reach through the VPN in your /etc/hosts file.

MySQL: Clean shutdown

You want to shutdown MySQL as cleanly as possible, perhaps because you want to create backups or want to do an upgrade.

Assumptions

  • You are running MySQL 5.5 or later

Procedure

If possible, stop all incoming connections (for example, from application servers).

On a slave or replication server, stop the I/O thread (which grabs updates from the master) and wait for the SQL thread to process all:

MySQL: Setting up replication

This is a simple guide to setting up replication between MySQL servers.

Assumptions

  • You are using MySQL 5.5 or later;
  • The master server is currently not being used and is not yet configured to use binlogs;
  • The slave server contains a perfect copy of the master server databases.

Procedure

On the master side, make sure the following statements are included in the /etc/my.cnf file:

MySQL: Identify invalid views

Symptoms

When querying a MySQL view, or when dumping a MySQL database, you get an error including the following text:

View ... references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them

A MySQL dump stops at that point.

You want to identify those views that return this error through a database query.

Udev: resolve a changed MAC address

Symptoms

After changing the MAC address (Ethernet address) of your network adapter, it does not get an IP address. This can happen within a virtual machine or when replacing the network card in a physical machine. If you try an ifconfig -a or an ip addr list, you see that the name of the network card has changed (for example, from eth0 to eth1).

Gettext: extracting translations

Symptoms

You have prepared your sources for translation with gettext. You actually have translations available, but those files contain too many translations (for example, for a larger project). Alternatively, you want to see if those files may contain translations you can use. You need to get only relevant translations extracted1.

OEM Database Control: security certificate

Symptoms

Oracle Enterprise Manager Database Control has a web front end that can be accessed through HTTPS. By default, the certificate used will not be trusted by any web browsers.

Solution

You can change the certificate, provided you have command-line access on the database server as the user Oracle was installed with. This will cause no downtime on the database, though Enterprise Manager itself will need to be restarted.

OEM Database Control: using HTTPS

Symptoms

Oracle Enterprise Manager Database Control has a web front end that can be accessed through either HTTP or HTTPS. The current protocol is not what you want.

Solution

You can change the protocol, provided you have command-line access on the database server as the user Oracle was installed with. This will cause no downtime on the database, though Enterprise Manager itself will need to be restarted.

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by Dr. Radut