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Re: NON-trivial regular expression problem (could not find on google)
From: |
Harry Putnam |
Subject: |
Re: NON-trivial regular expression problem (could not find on google) |
Date: |
Sat, 18 Jan 2003 21:38:16 GMT |
User-agent: |
Gnus/5.090008 (Oort Gnus v0.08) Emacs/21.3.50 (i686-pc-linux-gnu) |
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?
- NON-trivial regular expression problem (could not find on google), Instant Democracy, 2003/01/18
- Re: NON-trivial regular expression problem (could not find on google),
Harry Putnam <=
- Re: NON-trivial regular expression problem (could not find on google), Kai Großjohann, 2003/01/18
- Re: NON-trivial regular expression problem (could not find on google), AW, 2003/01/18
- Re: NON-trivial regular expression problem (could not find on google), Edi Weitz, 2003/01/18
- Re: NON-trivial regular expression problem (could not find on google), Larry Clapp, 2003/01/18
- Re: NON-trivial regular expression problem (could not find on google), Dr. Yuan Liu, 2003/01/18
- Re: NON-trivial regular expression problem (could not find on google), John W. Krahn, 2003/01/18
- Re: NON-trivial regular expression problem (could not find on google), William Park, 2003/01/18
- Re: NON-trivial regular expression problem (could not find on google), Peter J. Acklam, 2003/01/19