Marcin, applying this to the 2-variable question:
$ test "$SSH_TTY$SSH_CLIENT"; and echo "not empty"; or echo "unset or empty"
> unset or empty
> $ ssh localhost
> [...]
> $ test "$SSH_TTY$SSH_CLIENT"; and echo "not empty"; or echo "unset or
> empty"
> not empty
On Tue, Nov 11, 2014 at 5:51 PM, Glenn Jackman <jack...@pythian.com> wrote:
> I suspect what is happening (this is true in bash, I'm speculating about
> fish) is that an unset variable is substituted with nothing (not the empty
> string, but with nothing). Then the `test` command receives exactly one
> argument: "-n". When `test` is given a single argument, the result is true
> if that argument is not empty. This is true for the string "-n".
>
> So another way to write the test is simply
>
> if test $NOT_SET_VARIABLE; ...
>
>
> Demo
>
> $ set -q foobar
>> $ test $foobar; and echo "not empty"; or echo "unset or empty"
>> unset or empty
>> $ set foobar ""
>> $ test $foobar; and echo "not empty"; or echo "unset or empty"
>> unset or empty
>> $ set foobar abc
>> $ test $foobar; and echo "not empty"; or echo "unset or empty"
>> not empty
>
>
>
>
> On Tue, Nov 11, 2014 at 5:33 PM, Greg Reagle <greg.rea...@umbc.edu> wrote:
>
>> That's very interesting. I get the same problem. I don't think
>> anything is wrong with your code. I think something fishy is going on
>> with fish, but I don't know what. It looks like it might even be a bug
>> in fish. I would expect test -n to be the opposite of test -z, but that
>> is not true sometimes.
>>
>> There are a few workarounds.
>>
>> I find that test -z works fine.
>>
>> Another way to test a variable is
>> if test ab"$variable"cd = abcd; echo zero; else; echo non-zero; end
>>
>> --
>> http://www.fastmail.fm - Access all of your messages and folders
>> wherever you are
>>
>>
>>
>> ------------------------------------------------------------------------------
>> Comprehensive Server Monitoring with Site24x7.
>> Monitor 10 servers for $9/Month.
>> Get alerted through email, SMS, voice calls or mobile push notifications.
>> Take corrective actions from your mobile device.
>>
>> http://pubads.g.doubleclick.net/gampad/clk?id=154624111&iu=/4140/ostg.clktrk
>> _______________________________________________
>> Fish-users mailing list
>> Fish-users@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/fish-users
>>
>
>
>
> --
> *Glenn Jackman*
> Senior Software Developer
>
> *Pythian - Love your data*
> jack...@pythian.com
> Tel: +1 613 565 8696 Ext. 1478
> Mobile: +1 613 808 4984
> www.pythian.com
>
--
*Glenn Jackman*
Senior Software Developer
*Pythian - Love your data*
jack...@pythian.com
Tel: +1 613 565 8696 Ext. 1478
Mobile: +1 613 808 4984
www.pythian.com
--
--
------------------------------------------------------------------------------
Comprehensive Server Monitoring with Site24x7.
Monitor 10 servers for $9/Month.
Get alerted through email, SMS, voice calls or mobile push notifications.
Take corrective actions from your mobile device.
http://pubads.g.doubleclick.net/gampad/clk?id=154624111&iu=/4140/ostg.clktrk
_______________________________________________
Fish-users mailing list
Fish-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/fish-users
