exporting arrays

exporting arrays

[Bernd Eggink]

This message, too, semms to have gone to /dev/null the first time...

Excuse me if this is a stupid question, but why can't arrays be
exported? 

  ar=(x y z)
  export ar
  export
  zsh

"ar" shows up in the list, but in the following 'zsh'-invocation it is
unset. Is this intentional? I didn't find any  restrictions mentioned in
the manual.


-- 
Bernd Eggink
Regionales Rechenzentrum der Universitaet Hamburg
eggink@rrz.uni-hamburg.de
http://www.rrz.uni-hamburg.de/eggink/BEggink.html

Re: exporting arrays

[Zoltan Hidvegi]

> "ar" shows up in the list, but in the following 'zsh'-invocation it is
> unset. Is this intentional? I didn't find any  restrictions mentioned in
> the manual.

The restriction is in Unix.  The contents of an environment variable is
always a plain null-terminated string on Unix.  It is possible to hack
something as a workaround, but there is no prefect solution as far as I
know.  Neither bash not ksh exports arrays.  More precisely ksh93 does
export arrays but only the first array element gets into the enviromnet
(which is consistent since without subscritps a ksh array behaves like a
variable with the first array element as its value).

Exported functions has similar problems (just try foo='() {' bash to
see what I meen).  Probably that's why ksh93 does not have exported
functions and POSIX does not require it.

The foo()=... encoding to put functions into the environment seems to be
more reasonable and does not have the problem mentioned above.  It was even
included in some early POSIX drafts.  I wonder why doesn't bash use that
method instead of this ambiguous foo='() { ...' encoding.

Zoltan