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Re: The First Pure Shell Contest (PUSH): relativepath

Cross-posted to 3 groups.

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In comp.programming.contests Stephane CHAZELAS <Stephane.CHAZELAS@free.fr> wrote:
# 2011-08-19, 17:23(+00), Jens Schweikhardt:
# [...]
#> Write a POSIX shell function named 'relativepath' which takes as
#> arguments two absolute canonicalized pathnames, and stores the relative
#> path from the first to the second in the variable "result" or "." when
#> the arguments are the same. Example: relativepath /foo/bar /foo/baz sets
#> result to "../baz".
# [...]
# 
# In the not-answering-the-question category, what about:
# 
# printf '%s\n' "$1//$2/"|sed -e:1 -e'$!{N;b1' -e} -e'
#       s|/////*|///|;s|\(.*/\)\(.*/\)\1|\2|;:2
#           s|^[^/]*/\(\(.*/\)*/\)|\1../|;t2
#                s|^/||;s|/$||;s/^$/./'

Cool! Since semicolons are free, what about using them as pattern delimiters:

 printf '%s\n' "$1//$2/"|sed -e:1 -e'$!{N;b1' -e} -e'
       s;/////*;///;;s;\(.*/\)\(.*/\)\1;\2;;:2
           s;^[^/]*/\(\(.*/\)*/\);\1../;;t2
                s;^/;;;s;/$;;;s/^$/./'

Note to contestants: Not a valid entry due to sed, which cannot assumed
to be a builtin of the contest evaluation machine's shell :-)

Regards,

	Jens
-- 
Jens Schweikhardt http://www.schweikhardt.net/
SIGSIG -- signature too long (core dumped)

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Thread

The First Pure Shell Contest (PUSH): relativepath Jens Schweikhardt <schweikh@schweikhardt.net> - 2011-08-19 17:23 +0000
  Re: The First Pure Shell Contest (PUSH): relativepath Stephane CHAZELAS <stephane_chazelas@yahoo.fr> - 2011-08-19 18:13 +0000
    Re: The First Pure Shell Contest (PUSH): relativepath Jens Schweikhardt <usenet@schweikhardt.net> - 2011-08-19 19:12 +0000
      Re: The First Pure Shell Contest (PUSH): relativepath pk <pk@pk.invalid> - 2011-08-19 21:14 +0200
        Re: The First Pure Shell Contest (PUSH): relativepath Jens Schweikhardt <usenet@schweikhardt.net> - 2011-08-19 19:29 +0000
          Re: The First Pure Shell Contest (PUSH): relativepath pk <pk@pk.invalid> - 2011-08-19 21:37 +0200
            Re: The First Pure Shell Contest (PUSH): relativepath Jens Schweikhardt <usenet@schweikhardt.net> - 2011-08-19 20:04 +0000
              Re: The First Pure Shell Contest (PUSH): relativepath pk <pk@pk.invalid> - 2011-08-19 22:25 +0200
                Re: The First Pure Shell Contest (PUSH): relativepath Jens Schweikhardt <usenet@schweikhardt.net> - 2011-08-19 21:08 +0000
  Re: The First Pure Shell Contest (PUSH): relativepath Rainer Weikusat <rweikusat@mssgmbh.com> - 2011-08-19 19:58 +0100
    Re: The First Pure Shell Contest (PUSH): relativepath Jens Schweikhardt <usenet@schweikhardt.net> - 2011-08-19 19:23 +0000
      Re: The First Pure Shell Contest (PUSH): relativepath Rainer Weikusat <rweikusat@mssgmbh.com> - 2011-08-19 22:18 +0100
  Re: The First Pure Shell Contest (PUSH): relativepath Stephane CHAZELAS <Stephane.CHAZELAS@free.fr> - 2011-08-20 20:07 +0000
    Re: The First Pure Shell Contest (PUSH): relativepath Jens Schweikhardt <usenet@schweikhardt.net> - 2011-08-21 10:43 +0000
    Re: The First Pure Shell Contest (PUSH): relativepath Rainer Weikusat <rweikusat@mssgmbh.com> - 2011-08-21 15:14 +0100
      Re: The First Pure Shell Contest (PUSH): relativepath Janis Papanagnou <janis_papanagnou@hotmail.com> - 2011-08-21 18:28 +0300
      Re: The First Pure Shell Contest (PUSH): relativepath Stephane CHAZELAS <stephane_chazelas@yahoo.fr> - 2011-08-21 16:19 +0000
        Re: The First Pure Shell Contest (PUSH): relativepath Stephane CHAZELAS <stephane_chazelas@yahoo.fr> - 2011-08-21 20:12 +0000
  Re: The First Pure Shell Contest (PUSH): relativepath Rainer Weikusat <rweikusat@mssgmbh.com> - 2011-08-22 21:15 +0100
    Re: The First Pure Shell Contest (PUSH): relativepath Stephane CHAZELAS <stephane_chazelas@yahoo.fr> - 2011-08-23 18:23 +0000
      Re: The First Pure Shell Contest (PUSH): relativepath Rainer Weikusat <rweikusat@mssgmbh.com> - 2011-08-23 19:52 +0100
        Re: The First Pure Shell Contest (PUSH): relativepath Stephane CHAZELAS <stephane_chazelas@yahoo.fr> - 2011-08-23 21:56 +0000

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