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Re: Question re. export environment variable

Thanks, Bob.  That's the way I expected it to work.
I was just unsure of whether there was something
cygwin-specific, as it seems strange that something
like HOSTNAME is not marked for export at the time
that it is set.  I'll stick it into ~/.bashrc.


Fred Ma, fma at doe dot carleton dot ca
Carleton University, Dept. of Electronics
1125 Colonel By Drive, Ottawa, Ontario
Canada, K1S 5B6

Bob McGowan wrote:

> Fred, perhaps this will help:
> echo $TEST      # Test has no value, hence the blank line.
> $ TEST=noexport # Set but not exported
> $ echo $TEST
> noexport
> $ env|grep TEST # Nothing found, no output.
> $ export TEST   # Export it.
> $ env|grep TEST # And now it's found in the environment.
> TEST=noexport
> $ TEST=second   # Change its value.
> $ env|grep TEST # Same search as above, but the value is changed.
> TEST=second
> Perhaps the easiest way to look at it is to think of exporting as making a type
> of global variable.  Everyone (within certain limits; for the shell, only its
> children...) will see the exported variable.  If the value changes, it changes
> "everywhere".  I've quoted everywhere because this only applies to children
> invoked after the change.  So if TEST=second and you run an xterm, the new shell
> sees TEST=second.  Change TEST=third in the first shell, you still have
> TEST=second in the second shell, since it already got its value for TEST.  Start
> a third shell from the first, it will see TEST=third.  And so on.
> Fred Ma wrote:
> > Hello,
> >
> > I'm using cygwin bash 2.05b-8 (it's actually gnu).
> > I thought that $HOSTNAME was an environment
> > variable.  When I run gnu make (I'm pretty
> > sure this is not a make problem), $(HOSTNAME)
> > is empty.  It gets fixed if I do "export HOSTNAME"
> > before running make.
> >
> > Is there a way to check if the export command
> > has been applied to $HOSTNAME?  Does the
> > actual transcription of $HOSTNAME's value to
> > the environment happen only once, when
> > "export" is applied, or is there a continual
> > monitoring an mirroring of changes to $HOSTNAME
> > forever after applying "export"?
> --
> Bob McGowan
> Staff Development Engineer
> VERITAS Software
> rmcgowan at veritas dot com

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