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Re: wc command
From: |
Pádraig Brady |
Subject: |
Re: wc command |
Date: |
Mon, 22 Dec 2008 13:43:31 +0000 |
User-agent: |
Thunderbird 2.0.0.6 (X11/20071008) |
Eric Blake wrote:
> According to Andrew McGill on 12/22/2008 1:38 AM:
>> My guess is that while it would be friendly to provide a similar message for
>> wc (od, head, tail, etc), it would violate something posixy (and is
>> therefore
>> imposixable).
>
> It would be possible to add a conditional check, where if POSIXLY_CORRECT
> is not defined in the environment and a filter app is started with a tty
> as stdin and stderr (ie. the same criteria for what POSIX requires bash to
> use for whether a shell is interactive), then we issue a warning to
> stderr. Normally, we don't like adding additional uses of
> POSIXLY_CORRECT, but this particular idea may help stave off confusion.
> Care to write such a patch? It would need to be applied to all of the
> coreutils that can act as a filter, not just wc.
So you're proposing something like:
if (!POSIXLY_CORRECT && isatty(0) & isatty(2))
fprintf(stderr,"Please enter your text now, or Ctrl-d to end\n");
While logically correct, I'm not sure such a patch would
be that useful/desired. More code and more translations,
for something that should be quite obvious.
The OP entered `wc` accidentally, so it's not as if
they were confused about the way the filter operated.
99.999999999999999% of cases like this would be users
wait a while, and go "oops", Ctrl-c.
I'm all for helping new users, and giving meaningful
error messages, but I'm not sure the gain is worth the
effort of updating all filters.
I'm 40:60 for this proposal.
cheers,
Pádraig.