From: Harry Putnam <hgp@sbcglobal.net>
Subject: Re: NON-trivial regular expression problem (could not find on google)
Date: Sat, 18 Jan 2003 21:38:16 GMT [thread overview]
Message-ID: <m2n0lydtqi.fsf@sbcglobal.net> (raw)
In-Reply-To: 7606630f.0301181219.60384da2@posting.google.com
democrat@india.com (Instant Democracy) writes:
Let me say first, that I'm not sure I understand the problem but
after several readings it appears to be simply that you want to
reduce the file names to the last componenet only.
> A frequent problem involves simplifying a pathname. The string format we
> can expect to encounter is covered by the following three examples:
Overlooking the `"' part for a moment, that problem is often handled
with shell operators % # or %% ## rather than regex.
> "dir.name/../dir/../file"
> "dir/../d2/../file.ext"
> "d1/d2/../../file.ext"
In any of the bourn based shells.
var='dir.name/../dir/../file'
echo ${var##*/}
file
> The "" are part of the string, and not just string delimiters. These
> strings are inside regular text on the line. The paths are never
> absolute so that you will not encounter "/d1/file.ext".
In the above scheme they can be handled like:
var='"dir.name/../dir/../file"'
echo ${var##*/}|sed 's/\"//'
file
> The task is to eliminate patterns such as
> DIRNAME/../
> from the path because they are redundant.
>
> For lines which do not have ../.. in them, this is
> trivial, for example by regexp in sed, emacs etc.
Not sure I see why you would need to eleminate anything if
../.. is not present.
> The real problem is constructing a regular expression for
> the DIRNAME before the /..
>
> This DIRNAME can be described as a string that contains neither
> / not double-dot but anything else. Perhaps I am overlooking
> something else about DIRNAME.
Do the shell operators mentioned solve it? Or have I missed the boat
entirely?
next prev parent reply other threads:[~2003-01-18 21:38 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-01-18 20:19 NON-trivial regular expression problem (could not find on google) Instant Democracy
2003-01-18 21:38 ` Harry Putnam [this message]
2003-01-18 21:46 ` Kai Großjohann
2003-01-18 22:52 ` AW
2003-01-18 23:03 ` Edi Weitz
2003-01-19 0:27 ` Larry Clapp
2003-01-19 0:36 ` Dr. Yuan Liu
2003-01-19 0:53 ` John W. Krahn
2003-01-19 1:05 ` William Park
2003-01-19 12:17 ` Peter J. Acklam
2003-01-19 19:26 ` Dr. Yuan Liu
2003-01-20 9:15 ` Peter J. Acklam
2003-01-24 18:56 ` Yuan Liu
2003-01-24 11:20 ` Bruce Barnett
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