LinuxQuestions.org
Latest LQ Deal: Linux Power User Bundle
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Newbie
User Name
Password
Linux - Newbie This Linux forum is for members that are new to Linux.
Just starting out and have a question? If it is not in the man pages or the how-to's this is the place!

Notices


Reply
  Search this Thread
Old 12-09-2008, 01:44 PM   #1
Jude Terror
LQ Newbie
 
Registered: Dec 2008
Posts: 27

Rep: Reputation: 0
Is it possible to manipulate strings INSIDE awk scripts?


Hello, I'm new to the forums, though I've used them as a reference many times in the past and found them extremely helpful. A little background info on my skills - I've been teaching myself Linux shell scripts as well as php through reverse engineering. I'm pretty good at looking at how something is done and then feeling my way through creating a script to do what I need, but I can't just write one off the top of my head - yet.

Anyway, I've been working on this problem for two days, and I can't seem to figure out a solution. I am working with a program that uses an xml file to process jpeg images. In many cases, one set of files may contain several hundred jpg images, which are ordered into pages with the xml file. For example, there may be filename_0001.jpg, filename_0002.jpg, filename_0003.jpg, etc., and inside the xml file, there is data about the image contained inside an xml field for each image:

Code:
<page leafNum="1">
<width>123</width>
<height>123</height>
</page>
<page leafNum="2">
<width>123</width>
<height>123</height>
</page>
...and so on, but with many more fields inside the page tags, and with hundreds or thousands of pages.

Now, I have come into some situations where I need to insert a page or two into the mix, which would be a major pain, since it would require changing the "leafNum" for every single page after the pages I insert in the xml file to make space, as well as renaming each of the jpeg files in the same fashion. SO I decided that I should devote some time to automating this process with shell scripts.

Now, I WAS able to successfully create a script to rename the jpeg files, adding a number of my choice onto the file numbering. However, I am hitting a wall with the XML.

What I have right now is this:

Code:
awk '{if ($2 ~ /^leafNum/)
{$test=$2;
print $test}
}' filename.xml
The print line exists just so that I can see the output as I try to figure this out.

This works to identify the lines that need to be changed - those containing "leafNum." It then takes the "leafNum="###">" string from that line and sticks it in the $test variable for me, which I hoped to use to manipulate it. I tried several methods of string manipulation on the $test variable, including sed and simply using things like $test=${test#leafNum} to no avail - errors every time. I'm not sure if they just don't work inside an awk command, or if they require a different syntax. I also tried putting the awk command inside a do loop that was processing the file line by line, echoing the read variable into the awk command to search for the leafNum, but I couldn't get the syntax right on that either.

I need to cut that $test variable, which currently reads "leafNum="###">" (where ### can be any integer from 0 to 9999, without any excess zeros) so that I can add a variable $X (a number which I will define based on how many pages I am inserting), and then rewrite the line in the xml file - something like:

Code:
print "<page leafNum="$test">"
...though I haven't gotten around to working that part out either, as I'm stuck on this first part. So here is the plan for my script:

Code:
awk '{if ($2 ~ /^leafNum/)
{$test=$2;

(manipulate this variable to just the numbers, and add to it)

(rewrite the xml line)

}

(ELSE print the line as normal)

}' filename.xml

(output to new file)
So, sorry about the really long post, but I thought I'd give you all the info I have. Does anyone have any suggestions for me?

Last edited by Jude Terror; 12-09-2008 at 01:45 PM.
 
Old 12-09-2008, 01:47 PM   #2
Jude Terror
LQ Newbie
 
Registered: Dec 2008
Posts: 27

Original Poster
Rep: Reputation: 0
I just realized that maybe I should have posted this in the programming forum?
 
Old 12-09-2008, 05:42 PM   #3
dandelot
LQ Newbie
 
Registered: Dec 2008
Posts: 3

Rep: Reputation: 0
manipulating string inside awk

echo "a=b" | awk '{ print $1; x=$1; t=split(x,a,"="); print t ; print a[1]; }'

and here is running the one-line script (it's in the file 'test')
sh test
a=b
2
a


split is one of a set of
built-in string manipulation functions in awk.
Hope this helps.
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
Can I use grep inside awk? Helene Programming 10 09-29-2015 09:48 PM
Awk Question to search specific strings grouped by blank lines rk4k Programming 6 07-08-2008 12:56 AM
shell command using awk fields inside awk one71 Programming 6 06-26-2008 05:11 PM
Some comments on awk and awk scripts makyo Programming 4 03-02-2008 06:39 PM
awk inside a makefile linux.fob Programming 2 10-12-2005 05:57 PM


All times are GMT -5. The time now is 02:36 PM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration