Re: [Xen-devel] xl command autocompletion: domain names

[John Haxby <john.haxby@xxxxxxxxxx>]

On 08/11/13 15:11, Ian Jackson wrote:
> John Haxby writes ("Re: [Xen-devel] xl command autocompletion: domain names"):
>> > On 06/11/13 17:13, Ian Jackson wrote:
>>> > >  bash_completion_sudo () {
>>> > >     if [ x"`whoami`" = xroot ]; then "$@"
>>> > >     else ${BASH_COMPLETION_SUDO-sudo} "$@"; fi
>>> > >  }
>>> > >  bash_completion_sudo xl list
>> > 
>> > It's amazing how old constructs make it into new shell scripts for all
>> > the wrong reasons.
> ...
>> > For some reason there has been a resurgence in the belief that you need
>> > the x's _and_ the quotes.  You don't.  Ideally you'd eschew the archaic
>> > construct altogether.
> The x's are there in case the string looks like an operator for
> test(1).  Depending on the exact syntax of the expression inside [ ],
> it can be ambiguous.  In this case it's OK (I think) but IMO it's a
> good habit to always include the x whenever passing string data values
> to test(1).
> 

I hadn't thought of that ...

Except that test doesn't seem so easily fooled:

test -f == root && echo oops
if [ -f == root ]; then echo oops; fi
if [ -f /etc/passwd ]; then echo phew; fi

At least that's the case for bash; dash doesn't like it.

Still, that's today's new Linux/Unix thing so I'm happy!

jch

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