Re: t0090-cache-tree fails due to wc whitespace

From: Thomas Rast <trast@student.ethz.ch>
Date: Dec 14, 2011, 15:43 UTC
Message-ID: <201112141643.06656.trast@student.ethz.ch>
In-Reply-To: <7F1792D2-8ED4-4546-8ED4-52B95E0AE9FC@silverinsanity.com>

Brian Gernhardt wrote:

> 
> It's time for my periodic complaint: People assuming `wc -l` outputs
> just a number.  wc on OS X (and perhaps other BSD-like systems)
> always aligns the output in columns, even with the -l flag.

Oops.

> Generally this results in a quick patch from me to remove some
> unneeded quotes.  However, this time it's used in a more complex
> manner:

[...]

> -           "($(git ls-files|wc -l) entries, 0 subtrees)" >expect &&
> +           "($(git ls-files|wc -l|sed -e 's/^ *//') entries, 0 subtrees)" >expect &&

I'm tempted to say we should define

test_wc_l () {
	test $# = 0 || error "bug in test script: passing arguments to wc -l is not portable"
	wc -l | tr -d -c 0-9
}

just to avoid issues if any wc comes across and prints a tab for padding or says "hi, the number of lines you wanted to know is: 42".

(Oddly, according to 'man 1p wc' here, the POSIXly correct format in the absence of options is

  "%d %d %d %s\n", <newlines>, <words>, <bytes>, <file>

Taking it literally would mean no padding/alignment whatsoever. Neither GNU wc on my Linux exactly conforms to this.)

-- 
Thomas Rast
trast@{inf,student}.ethz.ch