How to extract string from filename
Willem van der Walt
wvdwalt at csir.co.za
Wed Jul 29 11:58:03 UTC 2015
I usually use rev twice, e.g.
echo blablabla_bla_p123_default.mp3|rev|cut -f2 -d'_'|rev
On Wed, 29 Jul 2015, Tony Baechler wrote:
> Hi all,
> The recent discussion on shell scripts got me thinking. A couple of posters
> invited people to post problems they're having with scripts to the list, so
> here goes.
> I have not actually written a script for this because I'm not sure how to go
> about it. I would normally use cut, but I need to cut from right to left.
> The cut help doesn't indicate a way to do this. You can only cut from the
> beginning of the line or a range of bytes. The problem is each line
> (filenames, to be exact) are of different lengths, so it's impossible to know
> what range of bytes I need.
> What I'm trying to do is extract the BBC PID from the downloaded files. It's
> a lower case alphanumeric string which starts with a letter and is eight
> characters. In my case, the first letter is always "b" or "p," so if I could
> use something like grep to just extract the first lower case letter followed
> by a number up to the next underscore, that would be good. I don't think
> grep will just print a matching phrase, only the matching line. Here are
> some example filenames:
> As you can see, they all follow a similar format. If I could go from right
> to left, I would simply cut "_default.mp3" and extract the preceeding 8
> bytes, but I can't figure out how. What I'm trying to do is first extract
> the PIDs, hopefully preserving the filenames in the process. Once they are
> extracted (or printed to stdout), I want to use wget to download the BBC
> programme page. If you go to www.bbc.co.uk/programme/bXXXXXXX, you'll get a
> web page displaying the broadcast date, description and notes. I would like
> to download those pages.
> Any help with this would be greatly appreciated. Thanks in advance.
> Tony Baechler, Baechler Access Technology Services
> Putting accessibility at the forefront of technology
> mailto:bats at batsupport.com
> Phone: 1-619-746-8310 Fax: 1-619-449-9898
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