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From: Rainer Weikusat <rweikusat@mssgmbh.com>
Newsgroups: comp.unix.shell,comp.unix.programmer,comp.programming.contests
Subject: Re: The First Pure Shell Contest (PUSH): relativepath
Date: Tue, 23 Aug 2011 19:52:25 +0100
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Stephane CHAZELAS <stephane_chazelas@yahoo.fr> writes:
> 2011-08-22, 21:15(+01), Rainer Weikusat:
>> Jens Schweikhardt <schweikh@schweikhardt.net> writes:
>>>     The First Pure Shell Contest (PUSH)
>>>
>>>               == Motivation ==
>>>
>>> The shell is not known for powerful string processing.
>>
> [...]
>>     echo "<$1> not absolute or canonical"
> [...]
>>     while test -n "$fa" -a "$fa" = "$fb";
> [...]
>> 	if test -n "$fb" -o "$fa" != "$rb"
> [...]
>
> We may want to add those test cases:
>
> /=/x         /            0 ../..
> /            \\\\\\\\     1 <\\\\\\\\> not absolute or canonical

No. You 'might' (actually, you should) want to point out the problem
with the two statements above, namely,

	In addition, the string comparison binary primaries '=' and
	"!=" shall have a higher precedence than any unary primary.

      http://pubs.opengroup.org/onlinepubs/9699919799/utilities/test.html

and maybe even write that the obvious fix is
to rewrite this as

	test -n "$fa" && test "$fa" = "$fb"

(and similar for the other case).

That you, you'd still had had the chance to boast with your superior
knowledge about pecularities of the UNIX(*) standard but in a way
which had a chance to be useful to readers.
      
> What about:
>
> relativepath(){ for i do case $i/ in /|[!/]*|*/./*|*/../*|*?//*|//?*)
> result="<$i> not absolute or canonical";return 1;esac;done
> p=${1%/} r= b=${2%/}/;while :;do case $b in "$p"/*)r=$r${b#"$p"/}
> r=${r%/};result=${r:-.};break;esac;p=${p%/*} r=../$r;done;}

What about

dd if=/dev/urandom bs=1 count=1024 | base64 | fold -b -w 26

?

Granted, it doesn't solve the problem but its as unintelligible as
the gibberish above.