The content of this blog is my personal opinion only. Although I am an employee - currently of Imagination Technologies's MIPS group, in the past of other companies such as Intellectual Ventures, Intel, AMD, Motorola, and Gould - I reveal this only so that the reader may account for any possible bias I may have towards my employer's products. The statements I make here in no way represent my employer's position, nor am I authorized to speak on behalf of my employer. In fact, this posting may not even represent my personal opinion, since occasionally I play devil's advocate.

See http://docs.google.com/View?id=dcxddbtr_23cg5thdfj for photo credits.

Saturday, November 12, 2011

Why depend on UNIX environment variables?

Previously I have posted about how I find tools that depend on sourcing csh files to get environment variables set a real pain to deal with. Largely because I don't have good ways of automating such procedures, both for use and test. And also because of environment variable interference.

So, I ask myself: Q: why depend on environment variables?

Then I remember how excited I was to learn of shell environment variables.

By setting an environment variable I could arrange for a parameter to be passed from the outside world right into the middle of a tool. Without having to modify any of the interveing levels.

No need to create argument parsing code.

In fact, in Bell Labs type shells,argument parsers are implicitly created for environmrnt variables:
VAR1=val1 VAR2=val2 program options...

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