* variable/array element question
@ 2011-09-19 20:22 david sowerby
2011-09-19 21:15 ` Benjamin R. Haskell
0 siblings, 1 reply; 2+ messages in thread
From: david sowerby @ 2011-09-19 20:22 UTC (permalink / raw)
To: zsh-users
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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?
I have bash and dash installed and neither have a problem with '-', don't have ksh so don't know about it.
Thanks in advance of the answer -----------------david
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: variable/array element question
2011-09-19 20:22 variable/array element question david sowerby
@ 2011-09-19 21:15 ` Benjamin R. Haskell
0 siblings, 0 replies; 2+ messages in thread
From: Benjamin R. Haskell @ 2011-09-19 21:15 UTC (permalink / raw)
To: david sowerby; +Cc: zsh-users
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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
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