Re: variable/array element question

["Benjamin R. Haskell" <zsh@benizi.com>]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1708 bytes --]

On Mon, 19 Sep 2011, david sowerby wrote:

> I did array=( $(ls -l <file>) )
> print $array 
>
> and got an error  Hmmmm......
> did print ${array[2,9]} and got the expected result: elements 2-9
> so zsh didn't like the first element
> Experimenting I did
>
> ls -l <file> | while read one two three four etc ; do print $one $two $three ; done
> same error
>
> So after using zsh for 2 years , I've just discovered that it doesn't 
> like variables to start with '-' .
> Obviously I can use Awk for this example, but I was curious as to why 
> this is?

It's not that it "doesn't like" them... ;-)

Parameter expansion happens before the command is executed.  The 
contents of the array are being interpreted as flags to the 'print' 
builtin.  E.g.

## -l makes `print` print each thing on a separate line
$ array=( -l a b c )
$ print $array
a
b
c
$ print -l a b c
a
b
c
$ array=( -what- this is ridiculous )
$ print $array
zsh: bad option -w

You can get around it with `print` via the '--' (stop processing) 
argument (which you can shorten to a single '-'):

$ array=( -what- this is ridiculous )
$ print - $array
-what- this is ridiculous
$



> I have bash and dash installed and neither have a problem with '-', 
> don't have ksh so don't know about it.

Bash has problems with hyphens in the same places Zsh does (generally). 
The differences are a different set of built-in commands (no 'print', 
AFAICT), and that Zsh treats things as arrays more readily (maybe 
there's an option you can set, but I hate having to type ${array[@]}). 
Example of bash treating an array item as an argument:

$ bash
$ array=( -v What %s earth )
$ printf ${array[@]}
### (no output)
$ echo $What
earth

-- 
Best,
Ben