Scripting in Korn Shell (exporting array variables)

[mdet]

Hi there,
I need to export a variable that is an array. I didn't find a way til now and it seems to me that arrays are strictly not exportable. Am I right or too stupid?
The ksh man page doesn't mention it.
Sample script (test.sh):
#!/usr/bin/ksh
echo "\$ARRAY: $ARRAY" # the whole thing
echo "\${ARRAY[0]}: ${ARRAY[0]}" # the first element


Command Line Input:
$set -A ARRAY first second
$export ARRAY
$echo $ARRAY
first second
$./test.sh

$


Furthermore inside the above script ARRAY is empty.
Is there anybody out there who can explain that to me. What is the difference between an array and a normal environment variable (if there is such)?.

Any hints are appreciated.

 

[aigles]

Try this :

Export your array :

OIFS=$IFS
IFS="°" # Or another char not used in ARRAY
export ARRAY_Values="${ARRAY[*]}"
IFS=$OIFS

In your script test.sh, import the array :

OIFS=$IFS
IFS="°"
set -A ARRAY $ARRAY_Values
IFS=$OIFS

Jean Pierre.

 

[tikual]

All work fine in my linux and Sun boxes. Your output in command line seems adnormal. If you are really using Korn Shell. The output of 'echo $ARRAY' should be 'first' only. So, I guess that you may be using different shell in command line.

tikual

 

[aigles]

On my AIX box, the export of an array doesn't work :

> cat test.sh
#!/usr/bin/ksh
echo "\$ARRAY : $ARRAY" # the whole thing
echo "\${ARRAY[0]}: ${ARRAY[0]}" # the first element
echo "\${ARRAY[1]}: ${ARRAY[1]}" # the second element

echo "\nVariable(s) ARRAY :"
set | grep ARRAY

> set -A ARRAY first second
> export ARRAY
> echo ${ARRAY[*]}
first second
> set | grep ARRAY
ARRAY[0]=first
ARRAY[1]=second

> ./test.sh
$ARRAY : first
${ARRAY[0]}: first
${ARRAY[1]}:

Variable(s) ARRAY :
_='\nVariable(s) ARRAY :'
ARRAY[0]=first
>


Jean Pierre.

 

[mdet]

Mercy Jean Pierre!
it's not a straightforward or elegant solution but it works fine.
Tikual, I have to apologize, you're right my command line shell is the Z-shell (thanks for your hint I forgot) and a comparison of ksh and zsh man pages revealed differences in referencing arrays and it's elements. But the script definitely forks as a ksh child.
It's still a mystery to me why exporting an array is different from exporting a scalar.

Thanks again.

 

[tikual]

ok, let's see the output by command 'set'. See what is the setting of ARRAY in there.

tikual

 

[mdet]

Hi Tikual,
now I'm stricly on Korn Shell and modified the Skript (just grep'ing the output of "set&quot:
#!/usr/bin/ksh
set|grep ARRAY

Command Line Input:
$unset ARRAY # to be sure nothing's there
$set -A ARRAY first second
$export ARRAY
$./test.sh
$ARRAY=first
Well, obviously ARRAY is exported as a scalar and for that reason it only holds "first". Now, let's declare ARRAY explicitly as a scalar variable.
Command Line Input:
$unset ARRAY # to be sure nothing's there
$export ARRAY=first
$export ARRAY
$./test.sh
ARRAY=first
$

Same result.
My conclusion is: You can't export arrays the way you do it with scalars. Furthermore Z-shell and korn-shell environments are incompatible regarding array variables. I did the same test with zsh as the command line shell and found out that ARRAY even isn't exported neither as scalar nor as array (the script yields nothing).

mdet.

 

[Ygor]

From 'man ksh'

The shell supports a limited one-dimensional array facility.
:
The export built-in command does not handle arrays properly.
Only the first element of an array is exported to the environment.

 

[mdet]

Lucky you are Ygor,
under Solaris the ksh man page doesn't mention that. Where did you get that from?


mdet.

 

[Ygor]

Above quote from is from HP-UX man pages.

Someone has made the O'Reilly Unix CD Bookshelf available online (!!) , so useful info on arrays can be found here...

http://www.ittepic.edu.mx/eBooks/computacion/80oreilly/books/unix2/ksh/ch06_03.htm