Re: bug with 'test'

[Eric Blake]

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You sent mail to the obsolete bug-sh-utils; it was forwarded to the
now-current bug-coreutils list instead.

According to Adam Chou on 12/8/2005 5:27 PM:
> test -v, test --version, test -h, and test --help do not work. they just
> return me to the command line. i have tried GNU sh-utils 2.0, coreutils
> 5.2.1 and coreutils 5.0. i wasn't aware of a newer version out to try.

The latest stable version of coreutils is 5.93:
http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00058.html


> other
> people on irc have confirmed that their versions also fail to output
> anything. i also specified the full path by doing /usr/bin/test but got the
> same results.

Careful - most shells have a builtin test, so "test --help" probably
invoked the shell builtin whereas "/usr/bin/test --help" invoked the
coreutils version.

Now some comments on the first reply...

According to The Wanderer on 12/8/2005 8:06 PM:
> Since I happened to have the source sitting around, I took a look, and
> apparently this is intentional for the binary named 'test'. The binary
> named '[' will react correctly to both of those options if no ']'
> argument is provided, but according to the source, 'test' is required by
> POSIX to respond to either of those options by exiting silently with
> status 1.

Almost.  POSIX requires "test --help" and "[ --help ]" both to exit
silently with status 0 (success), since they are non-zero length
one-argument expressions.

>
> This would appear to me to be a bug in the documentation, in that the
> man pages for 'test' and '[' are identical (actually, on my system, the
> latter is a symlink to the former) but their behaviour differs. I'm
> not sure how best to fix it.

How so?  On my system, the man page lists 5 forms for the utility:
       test EXPRESSION
       test

       [ EXPRESSION ]
       [ ]
       [ OPTION

Therefore, the ONLY way to get --help or --version (the only two supported
options) is to use the spelling [, provide just one option, and omit a
trailing ].

>
> (Hmm. A possible unintended behaviour in 5.93: '[ ] --help', rather than
> exiting silently or printing the usage message, reports "missing ']'".)
>

Nope, that's not a bug.  Here, you have the start of a two-argument
expression, but left off the trailing ].  According to the synopsis, you
can only use a single option when there are no other arguments, so this is
indeed a syntax error and [ is correct in reporting a missing ']'.  If you
do add the trailing ], as in "[ ] --help ]", you will then get a different
syntax error, since ] is not a valid first token in a 2-token expression.

- --
Life is short - so eat dessert first!

Eric Blake             address@hidden
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