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UNIX for Dummies Questions & Answers
What is meant by subprocesses?
Post 302406224 by Straitsfan on Monday 22nd of March 2010 10:21:40 AM
03-22-2010
My apologies -- but your explanation is fine. So I'm guessing that a subprocess consists of other executions required to carry out the primary executions of said instructions?
so when something is 'known' to a subprocess, it means what?
Here are the paragraphs that confused me:
"Some of the variables discussed above are used by commands you may run -- as opposed to the shell itself -- so that they can determine certain aspects of your envrionment. The majority, however, are not even known outside the shell.
This dichotomy begs an important question: which shell "Things" are known outside the shell, and which are only internal? This question is at the heart of many misunderstandings about the shell and shell programming. Before we answer, we'll as it again in a more precise way: which shell "things?" are known to subprocesses? Remember that wenever you enter a command, you are telling the shell to run that commmand in a subprocess; furthermore, some complex programsmay start their own subprocesses. Now for the answer, which (like many UNXI concepts) is unfortunately not as simple as you might like. "A few things are known to subprocesses, but the reverse is not true: subprocesses can never make these things known to the processes that created them.
Which things are know depends on whether the subprocess in question is a bash program or an interactive shell. If the subprocess is a bash program, then it's possible to propagate nearly every type of thing we've seen in this chapter -- options and variables -- plus a few we'll see later."
To which I respond: Huh?
I ask because the following section i the book concerns what are called environment variables, and if I know what a subprocess is, then I can make sense of the section better.
Maybe I should have just quoted this at the beginning, come to think of it. Apologies again.
so when something is 'known' to a subprocess, it means what?
Here are the paragraphs that confused me:
"Some of the variables discussed above are used by commands you may run -- as opposed to the shell itself -- so that they can determine certain aspects of your envrionment. The majority, however, are not even known outside the shell.
This dichotomy begs an important question: which shell "Things" are known outside the shell, and which are only internal? This question is at the heart of many misunderstandings about the shell and shell programming. Before we answer, we'll as it again in a more precise way: which shell "things?" are known to subprocesses? Remember that wenever you enter a command, you are telling the shell to run that commmand in a subprocess; furthermore, some complex programsmay start their own subprocesses. Now for the answer, which (like many UNXI concepts) is unfortunately not as simple as you might like. "A few things are known to subprocesses, but the reverse is not true: subprocesses can never make these things known to the processes that created them.
Which things are know depends on whether the subprocess in question is a bash program or an interactive shell. If the subprocess is a bash program, then it's possible to propagate nearly every type of thing we've seen in this chapter -- options and variables -- plus a few we'll see later."
To which I respond: Huh?
I ask because the following section i the book concerns what are called environment variables, and if I know what a subprocess is, then I can make sense of the section better.
Maybe I should have just quoted this at the beginning, come to think of it. Apologies again.
Last edited by Straitsfan; 03-22-2010 at 11:33 AM..
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LEARN ABOUT DEBIAN
books
books(3) Coin books(3) NAME
books - Books Related to Open Inventor / Coin Here is a list of some of the better books for people that invested in software development with Open Inventor. If you have suggestions for additional books that ought to go on this list, please feel free to tell us about it. The Inventor Mentor (subtitle 'Programming Object-Oriented 3D Graphics with Open Inventor') This is an excellently written, detailed, tutorial-style introductory book for Open Inventor that takes you through all the fundamental design principles applied in the Open Inventor API, richly illustrated and with numerous, well documented code examples. The Inventor Mentor is getting a bit old, but do not let that put you off. It is as valid today as it was the day it was written, and we heartily recommend this book for anyone learning to use Open Inventor. ISBN 0-201-62495-8. You might also be able to find this book as a pdf file online, but we recommend having it in print. The Inventor Toolmaker This book explains how Open Inventor was designed for being extended by the users, and walks you through how to develop your own components that work with all aspects of Coin. ISBN 0-201-62493-1. You might also be able to find this book as a pdf file online, but we recommend having it in print. The Annotated VRML2.0 Reference Manual This book covers the VRML97 (aka VRML 2.0) standard, which Coin has implemented with its Inventor/VRMLnodes/* classes, which is an extension made beyond the Open Inventor V2.1 API. The VRML97 format has some significant differences from the Inventor and VRML1 formats, so it is a useful book if you want to use that part of Coin. ISBN 0-201-41974-2. You will find the specification documents for VRML97 online at http://www.web3d.org/. The Open GL Programming Manual This is the bible when it comes to OpenGL programming and is relevant for Open Inventor extenders that develop new nodes that implement or affect Open Inventor OpenGL rendering. There are many editions of this book since it is updated whenever new versions of OpenGL are standardized and comes out, so check that you have identified the latest edition if you order one. The Open Inventor C++ Reference Manual Although this book is directly relevant for Open Inventor, it does only cover the Open Inventor 2.1 API. This information is more or less also covered in the online doxygen doc for Coin, where you have it hyperlinked, and can also be generated offline from the Coin sources to have locally, so we do not think this book is very useful to have in print. We mention it anyway since it is an official documentation book for Open Inventor. ISBN 0-201-62491-5. Version 3.1.3 Wed May 23 2012 books(3)