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Customization of the system requires us to write programs to perform special tasks. Perl was the first of a group of scripting languages including python, tcl and scheme, to gain acceptance in the Unix world. It has since been ported to Windows operating systems also. Perl programming has, to some extent, replaced much shell programming as the Free Software lingua franca of system administration. More recently Python, PHP and Tcl have been advocated also.
The Perl language is a curious hybrid of C, Bourne shell and C-shell, together with a number of extra features which make it ideal for dealing with text files and databases. Since most system administration tasks deal with these issues, this places Perl squarely in the role of system programming. Perl is semi-compiled at runtime, rather than interpreted line-by-line like the shell, so it gains some of the advantages of compiled languages, such as syntax check before execution and so on. This makes it a safer and more robust language. It is also portable (something which shell scripts are not). Although introduced as a scripting language, like all languages, Perl has been used for all manner of things for which it was never intended.
Scripting languages have arrived on the computing scene with an alacrity which makes them a favorable choice to anyone wanting to get code running quickly. This is naturally a mixed blessing. What makes Perl a winner over many other special languages is that it is simply too convenient to ignore for a wide range of frequently required tasks. By adopting the programming idioms of well-known languages, as well as all the basic functions in the C library, Perl ingratiates itself to system administrators and becomes an essential tool.
SELT ASSESSMENT EXERCISES
1. Explain why system configurations tend to fall into a state of disorder over time.
2. What is meant by change management?
4.0 CONCLUSION
Configuration and maintenance are clearly related issues. Maintenance is simply configuration in the face of creeping decay. All systems tend to decay into chaos with time. There are many reasons for this decline, from deep theoretical reasons about thermodynamics, to the more intuitive notions above wear and tear. To put it briefly, it is clear that the number of ways in which a system can be in order is far fewer than the number of ways in which a system can be in a state of disorder, thus statistically any random change in the system will move it into disorder, rather than the other way around.
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5.0 SUMMARY
Configuration management is the administration of state in hosts or network hardware An other side of network setup is the policies, practices and procedures which are used to make changes to or to maintain the system as a whole, i.e. what humans decide as part of the system administration process.
System administration is often a collaborative effort between several administrators. It is therefore important to have agreed policies for working so that everyone knows how to respond to ‘situations’ which can arise, without working against one another. A system policy also has the role of summarizing the attitudes of an organization to its members and its surroundings and often embodies security issues.
The opposite side of the coin in configuration and maintenance is the management of significant changes, e.g. upgrades, redesign and replacement.
The need for automation has become progressively clearer as sites grow and the complexity of administration increases. Many ideas for automating system administration have been reported; Most of these have been ways of generating or distributing simple shell or Perl scripts. Some provide ways of cloning machines by distributing files and binaries from a central repository. In spite of the creative effort spent developing the above systems, few if any of them can survive in their present form in the future.
Monitoring tools have been in proliferation for several years. They usually work by having a daemon collect some basic auditing information, setting a limit on a given parameter and raising an alarm if the value exceeds acceptable parameters.
Customization of the system requires us to write programs to perform special tasks. Perl was the first of a group of scripting languages including python, tcl and scheme, to gain acceptance in the Unix world. It has since been ported to Windows operating systems also.
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6.0 TUTOR-MARKED ASSIGNMENTS
1. What is meant by configuration management in the context of network and system administration?
2. How is configuration information stored by devices?
3. Summarize the alternatives available for automating host management. What limitations does each of the alternatives have?
4. Discuss System configuration policy
7.0 REFERENCES/FURTHER READING
1. Burgess, M. (2004). Principles of Network and System Administration. (2nd Ed.).
Chichester, West Sussex , England: Wiley.
2. Forouzan, B.A, & Fegan, S.C. (2007). Data communications and Networking (4th Ed). Mc Graw Hill.
3. Limoncelli, T. A.,Hogan, C. J. & Chalup, S. R (2007}. The Practice of System and Network Administration. (2nd Ed.). Upper Saddle River, NJ: Addison-Wesley
4. Stallings, W. (2009). Data and computer communications ( 8th ed.). Upper saddle River, NJ.:
Pearson Education Inc.
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