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Nagios, 2nd Edition

Cover of Nagios, 2nd Edition by Wolfgang Barth Published by No Starch Press
  1. Nagios: System and Network Monitoring, 2nd Edition
    1. Foreword to the second edition
      1. What's New in the Second Edition?
      2. Information Sources on the Internet
    2. Introduction
      1. The tests
      2. The suppliers of information
      3. Keeping admins up-to-date
      4. Taking in information from outside
      5. Other tools for network monitoring
      6. About This Book
      7. Further notes on the book
      8. Note of Thanks
    3. I. From Source Code to a Running Installation
      1. 1. Installation
      2. 2. Nagios Configuration
      3. 3. Startup
    4. II. In More Detail...
      1. 4. Nagios Basics
      2. 5. Service Checks and How They Are Performed
      3. 6. Plugins for Network Services
      4. 7. Testing Local Resources
      5. 8. Plugins for Special Tasks
      6. 9. Executing Plugins via SSH
      7. 10. The Nagios Remote Plugin Executor (NRPE)
      8. 11. Collecting Information Relevant for Monitoring with SNMP
      9. 12. The Nagios Notification System
      10. 13. Passive Tests with the External Command File
      11. 14. The Nagios Service Check Acceptor (NSCA)
      12. 15. Distributed Monitoring
    5. III. The Web Interface and Other Ways to Visualize Nagios Data
      1. 16. The Classical Web Interface
      2. 17. Flexible Web Interface with the NDOUtils
      3. 18. NagVis
      4. 19. Graphic Display of Performance Data
    6. IV. Part IV Special Applications
      1. 20. Monitoring Windows Servers
      2. 21. Monitoring Room Temperature and Humidity
      3. 22. Monitoring SAP Systems
      4. 23. Processing Events with the EventDB
    7. V. Part V Development
      1. 24. Writing Your Own Plugins
      2. 25. Determining File and Directory Sizes
      3. 26. Monitoring Oracle with the Instant Client
    8. VI. Part VI Appendixes
      1. A. An Overview of the Nagios Configuration Parameters
      2. B. Rapidly Alternating States: Flapping
      3. C. Event Handlers
      4. D. Macros
      5. E. Single Sign-On for the Nagios Web Interface
      6. F. Tips on Optimizing Performance
      7. G. The Embedded Perl Interpreter
      8. H. What's New in Nagios 3.0?

Appendix G. The Embedded Perl Interpreter

Perl is an interpreted scripting language. When a Perl script is started, it is read by the Perl interpreter, checked for errors, transformed into executable code only at runtime, and finally executed. Programs in languages such as C or C++ are checked for errors, compiled only once, and saved as binary code that can be run directly. Here the checking and compilation process takes place just once—before the program is run for the first time—whereas a Perl script is checked and compiled each time it is run. This takes place at an astounding speed, but it still takes time.

But things get worse—for each script, no matter how small it is, the heavyweight Perl interpreter is loaded every time. It's as if, in ...

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