Very Computer

Hi,

I have a book called "The new KornShell Command and Programming
Language". In several chapters, it mentions "side effects" of
built-ins. I'm confused what's that so that I can't understand some
paragraphs. Any help is appreciated.

Lesley Yang

Submitted by "lesley Yang" to comp.unix.shell:

Quote:> Hi,

> I have a book called "The new KornShell Command and Programming
> Language". In several chapters, it mentions "side effects" of
> built-ins. I'm confused what's that so that I can't understand some
> paragraphs. Any help is appreciated.

> Lesley Yang

The cd command changes the current directory.  It changes the
value of $PWD and $OLDPWD as a side-effect.

Starting a new shell parses the file $ENV as a side-effect.

The creation of the file "/tmp/hello" is a side effect of the
following command (and so is the updating of the "last accessed"
timestamp on "/usr/bin/tee"):

    STR=$(print "hello world" | tee /tmp/hello)

Some times, the "side-effect" is the main reason for executing a
command.  The touch command, although not a ksh built-in, is
often used to update the timestamps on a file, but sometimes
it's used to create empty files.

Someone else may have a better explanation.

--
Andreas K?h?ri
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