Something like pid~=[bp][a-zA-Z0-9] in bash could extract a pid from a
filename. The ~= operator tells bash to use regular expressions for
matching. All of this would probably have to be part of a for loop to
get that done.
On Wed, 29 Jul 2015, Rob Harris wrote:
Date: Wed, 29 Jul 2015 10:39:19
From: Rob Harris <robh@xxxxxxxxxx>
Reply-To: Linux for blind general discussion <blinux-list@xxxxxxxxxx>
To: Linux for blind general discussion <blinux-list@xxxxxxxxxx>
Subject: Re: How to extract string from filename
Linux has or can have apache server running to give access to PHP, and I can
see that working better using the explode(string, separator-char) command
using the _ as separator,
zz=explode(string, char);
this gives an array of sub-string without the _'s, and you need the second
to last. There's another function to count elements in an array, so x-1
where x is the number of elements. Might be x-2 as first element is 0.
I oculd get more specific if I dipped into all my old, but still used, PHP
scripts.
implode(array, separator) like zz2=implode(array, char), can put it back as
a long string separated by the char.
I love the relative simplicity of PHP for all this.
It can suck in an entire file into a string then save the modified string to
a new, or back to the old, file.
You'd use .mp3 as separator in this first instance.
Hth, BobH.
----- Original Message -----
From: "Tony Baechler" <tony@xxxxxxxxxxxx>
To: "Linux for blind general discussion" <blinux-list@xxxxxxxxxx>
Sent: Wednesday, July 29, 2015 12:13 PM
Subject: How to extract string from filename
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:
5_live_Science_-_Coding_and_Computers_b062dj5j_default.mp3
Witness_-_The_Sinking_of_the_USS_Indianapolis_p02wdykn_default.mp3
Discovery_-_A_Scientific_View_of_Agriculture_p0053gbd_default.mp3
Click_-_05_10_2010_p00b18gp_default.mp3
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@xxxxxxxxxxxxxx
Phone: 1-619-746-8310 Fax: 1-619-449-9898
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