bug#24894: coreutils 8.4 : `test -s` without argument does not return an error

[Eric Blake]

tag 24894 notabug
thanks

On 11/07/2016 06:58 AM, BAECKEROOT Alain wrote:
> Dear gnu-coreutils team
> 
> We had a funny problem caused by `test` which does return "0" when an option 
> is given without any EXPRESSION 
> 
> The man page says (near line 15 or so) : 
>       An  omitted  EXPRESSION defaults to false.

You are correct that it states that, but it means that 'test' (with no
expression at all) is what results in a false return (that is, an
omitted expression is equivalent to zero arguments).  'test -s' is NOT a
case of an omitted expression; your expression was '-s'.  Since you
provided exactly one argument, you are testing whether '-s' is the empty
string (it is not, hence the true result).

The full POSIX rules are here:
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/test.html

> I expected an error (at least return code not zero) , or it would be nice to 
> be warned in the man page.

You are correct that the man page could probably do a bit better at
explaining that test's behavior is STRONGLY influenced by the number of
parameters present (and this is per POSIX rules, so it is not just
coreutils' test implementation, but ALL conforming implementations that
will behave the same way).

> -------------
> reference : On *AIX* 6.1 , with IBM's test , there is an error 
> 
> address@hidden:/i/w/l/w00/was> echo $SHELL
> /bin/ksh
> address@hidden:/i/w/l/w00/was> uname
> AIX
> address@hidden:/i/w/l/w00/was> test -s
> ksh: test: argument expected

That is a bug in AIX's ksh, which is not POSIX compliant.

> address@hidden:/i/w/l/w00/was> echo $?
> 1
> 
> This was the expected behavior :-)  

Sorry, but that behavior is contrary to POSIX.

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-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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