Re: [Help-bash] array indirection

[Dan Douglas]

On Friday, May 04, 2012 06:20:46 PM Bill Gradwohl wrote:

Can anyone explain why one pass of this loop works and then fails.

If it didn't work at all, or worked all the time I could understand, but working once and then quitting is confusing.

array=(11 12 13 14 15)
variableName='array'

for ((x=0; x<address@hidden; ++x)); do
   echo "array[${x}]=${!variableName[$x]}"
done
==================
Produces:
address@hidden 01.ycc# ./tst pass3
array[0]=11
./tst: line 33: !variableName[$x]: unbound variable


--
Bill Gradwohl

Don't loop over arrays that way. Either use a `for in' loop to iterate elements, or iterate keys. Also, indirection can't be done that way. There is no such expansion as "${!arrname[x]}" where x is anything other than @ or *.

I wrote an example of how this can be done here:

 

http://wiki.bash-hackers.org/syntax/arrays#indirection

 

Which demonstrates Bash's indirection operator and obtaining keys if necessary.

--

Dan Douglas

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