On 18/09/17 14:37, Terry Coles wrote:
On Sunday, 17 September 2017 11:52:00 BST Ralph Corderoy wrote:
BTW, this is all fairly basic shell scripting stuff, e.g. quoting with
"" or '' or ``, with a little knowledge of how Unix works. I know you
think you don't need to know it, and can stick with Python, or the
electronics, but you're clearly having a tough time of it learning
piecemeal from a hotchpotch of problems rather than a planned gentle
introduction.
Well that's me told :-)
I learnt from two of Unix's creators, Kernighan and Pike's _The Unix
Programming Environment_, http://amzn.to/16SVwhD and it's what I still
recommend, though the price seems to have kept pace with inflation over
the decades. There are second-hand ones available though.
That's the nicest RTFM I've ever had :-)
The problem I have is that I was never (and never will be) a software
developer. I have written snippets of code in various languages on both Unix
and Windows platforms for well over 30 years, but I have never sat down to
intensively write code; it has always been a means to make the electronics
work.
Taking the quoting of the strings in 'echo', every language and platform that
I have ever used has had a different policy on strings (single quotes, double
quotes, brackets and combinations thereof). I only mentioned the quoting
problem because I had done what I usually did for strings and then only
realised it was wrong when I read your response (at a time when I would be
unable to test it for a few days).
With 'exec' the story was different because I had never noticed this command
before. I read the man page when Bob mentioned it and as usual learnt little
because of the terminology used. I then looked around and stumbled across a
page that made some kind of sense. It was only when you said that my
definition was wrong that I went back and realised that I had found a definition
of exec(), not exec.
I do read books and online material to find out what I need to do, but since I
never trained as a software engineer, I frequently end up more confused than
when I started; hence my Janet and John queries on this list. Coupled with
the fact that I literally only do this sort of thing a few times a year (when
the hardware needs a platform to operate on), I suspect that I'd forget what I
learned by the time I needed it.
Anyway. I'm still grateful for any help given and I'll try not to be so dumb
in the future ;-(
Even for those of us that have been trained in programming and have
created things in software, this has been a learning experience, and I
am always grateful to Ralph and others for their explanations.
It's come a long way since PDP-8 Assembler and Primix, that's for sure.
Peter
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