shell parsing bug with &>

Ralf Friedl Ralf.Friedl at online.de
Mon Sep 3 05:34:46 UTC 2012


Rich Felker wrote:
> On Sun, Sep 02, 2012 at 11:35:04PM +0200, Yann E. MORIN wrote:
>   
>> On Sunday 02 September 2012 23:21:36 Rich Felker wrote:
>>     
>>> It seems busybox ash is misinterpreting "&>" as having some special
>>> meaning rather than being a "&" token followed by a ">" token.
>>>       
> Okay. The problem however is that unlike some other extensions, this
> one breaks the grammar and causes valid programs to have different
> behavior (rather than just making some otherwise-invalid programs
> valid with new behavior). There should at least be a way to turn it
> off.
What is the use of "&>" in a program? It it was common, bash would not 
use this as an extension.
The command
    cmd & > file
would execute cmd in the background and create an empty file "file". The 
file would most likely exist when cmd is running, although there is not 
guaranty. So that file could as well be created before calling cmd.


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