[ -z $FOO ] seems broken in beta13

[ -z $FOO ] seems broken in beta13

[Clint Olsen]

Hello:

I use [ -z $TERM ] to check for terminal settings, and since we revved up
from 2.5, I'm now forced to use $+TERM.

Now I get "argument expected".  Is this correct?

-Clint

Re: [ -z $FOO ] seems broken in beta13

[Zefram]

>I use [ -z $TERM ] to check for terminal settings, and since we revved up
>from 2.5, I'm now forced to use $+TERM.
>
>Now I get "argument expected".  Is this correct?

Yes.  If $TERM is empty, then $TERM will be removed from the command
line completely, leaving `[ -z ]`, which is a syntax error.  If you use
"$TERM" (note the quotes), then the result will be `[ -z "" ]`, which
is legal.

-zefram

Re: [ -z $FOO ] seems broken in beta13

[Hrvoje Niksic]

Zefram (A.Main@dcs.warwick.ac.uk) wrote:
> 
> >I use [ -z $TERM ] to check for terminal settings, and since we revved up
> >from 2.5, I'm now forced to use $+TERM.
> >
> >Now I get "argument expected".  Is this correct?
> 
> Yes.  If $TERM is empty, then $TERM will be removed from the command
> line completely, leaving `[ -z ]`, which is a syntax error.  If you use
> "$TERM" (note the quotes), then the result will be `[ -z "" ]`, which
> is legal.

I thought you got this behaviour only by turning on shwordsplit?

-- 
hniksic@srce.hr              |  Student of electrical engineering
hniksic@fly.cc.fer.hr        |  University of Zagreb, Croatia
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Re: [ -z $FOO ] seems broken in beta13

[Zoltan Hidvegi]

> >I use [ -z $TERM ] to check for terminal settings, and since we revved up
> >from 2.5, I'm now forced to use $+TERM.
> >
> >Now I get "argument expected".  Is this correct?
> 
> Yes.  If $TERM is empty, then $TERM will be removed from the command
> line completely, leaving `[ -z ]`, which is a syntax error.  If you use
> "$TERM" (note the quotes), then the result will be `[ -z "" ]`, which
> is legal.

Actually POSIX says that

with no arguments test should exit with status 1. 

With 1 argument it should exit true iff that argument is non-null (this
means that `test -n' and `test -z' both exit true).  

With 2 arguments: if $1 is a bang `!' exit true iff $2 is null.  If $1 is
an unary operator, exit true iff the unary test is true.

etc.

I'll modify zsh according to this.

Zoltan

Re: [ -z $FOO ] seems broken in beta13

[Bart Schaefer]

On Jun 10,  7:18pm, Hrvoje Niksic wrote:
} Subject: Re: [ -z $FOO ] seems broken in beta13
}
} Zefram (A.Main@dcs.warwick.ac.uk) wrote:
} > 
} > >I use [ -z $TERM ] to check for terminal settings, and since we revved up
} > >from 2.5, I'm now forced to use $+TERM.
} > >
} > >Now I get "argument expected".  Is this correct?
} > 
} > Yes.  If $TERM is empty, then $TERM will be removed from the command
} > line completely, leaving `[ -z ]`, which is a syntax error.  If you use
} > "$TERM" (note the quotes), then the result will be `[ -z "" ]`, which
} > is legal.
} 
} I thought you got this behaviour only by turning on shwordsplit?

Probably that was true at one time.

In any case, it would be nice to be able to get a Bourne-shell-compatible
"test" as well as a POSIX-compatible "test".  As demonstrated here before,
bash appears to use the POSIX semantics, but sh and ksh use the "argument
expected" semantics quoted above.

-- 
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