Child Processes

The following code snipplet defines two functions:

Aligning Multi-line Equations

It often makes reading equations a lot easier when breaking them up across lines:

Active Directory Name to Distinguished Name Conversion

This note demonstrates some exciting Perl magic. It presents several ways to convert a directory-like name of an object in Active Directory to a X.500 Distonguished name.


XFig is an drawing program which stores images in its own format (fig) which can be converted to most commonly used image and vector formats:

Unexpected Behaviour

This contains a list of weird behaviour.

Using a Sans Serif font

You’d like your document to use a Sans Serif font

See Fonts

Fuzzy fonts in PDF documents

The fonts in your PDF document are all fuzzy

See Font Encoding and Generating PS/PDF Documents

Mangled ToC pages and references

TOC pages and references are all wrong

See Compilation of LaTeX Documents

No fancy headers in index

Using the package fancyhdr does not affect the index

See Indexes

Wrong references to figures

Referring to an figure does not produce the correct reference

See Graphicx

Incorrectly placed figures

Figures are moved to the end of the document

See Floats

Incorrect page references

Using addcontentsline does not refer to the correct page

See Adding TOC Lines

Fancybox breaks ToC

Package fancybox breaks table of contents

This is a known bug with this package.

LaTeX2HTML hangs

LaTeX2HTML locks while processing the document


Signal Trapping Using Functions

You can easily catch signals thrown at your process and call a function which needs to be defined beforehand:


References allow you to refer to arbitrary positions inside your document.

Power over TCP

  • Power is transmitted as payload in the TCP packet.
  • During the TCP handshake, the requested current and voltage are encoded in optional header options.
  • To power on, the device opens a connection to a Power Provider and specifies the parameters for the required power in the optional TCP header.


  • Digital Power: The power is transmitted digitally. There is no loss due to resistance of the cable.
  • Discovery: A device can discover a Power Provider on the local network using the Dynamic Power Discovery Protocol (DPDP).
  • Routing: The inherent routing capabilities of the Internet Protocol are utilized and power is routed to the endpoint wherever it is needed.
  • Multiple Endpoints: Due to the utilization of TCP, an endpoint has access to several connections carrying different configurations of current and voltage.
  • Wireless LAN: Mobile devices are enabled to power on and operate without any connection to the power grid. A battery is not required any more. Internet Service Providers can enhance their hot spots to provide power and network connectivity at the same time.
  • VPPN: Corporate users can rely on their employer to provide power via Virtual Private Power Networks (VPPNs).
  • Firewalls: Unauthorized power transmission can be intercepted and the power can be reused by the device, either to power the infrastructure or to offer power to internal devices.
  • Encryption: By encrypting power, the power provider can prevent unauthorized usage of the transmitted payload.


  • In data centers, the distribution of power plugs is not necessary any longer because a single power provider can transmit power via the existing networking infrastructure.
  • A firewall attacked by a malicious power provider can reuse the received power.
  • The first law of thermodynamics (conservation of energy) does not apply to Power-over-TCP because a broadcast is able to distribute (the same) power to multiple endpoints at the same time.

Perl Module Errno

This module provides a variable containing the results for all known error constants:

PDF Bookmarks

Sometimes it is desirable to add custom lines to the list of bookmarks inside a PDF file: