Shell Programming and Scripting

I probably could have done this at one time, but, the years and no need has left my scripting skills lacking and I'm unable to work this problem out. https://www.unix.com/images/smilies/frown.gif


Using Linux, have a great many xml files in which there may be multiple occurrence of a line of the form:

<sub_unit type="County" name="Campbell" geog_id="null">

The xml filename that contains these lines is of the form:

ky.abc.123.xml

Where the first two letters are state abbreviations.

What I need to do is grab the first two letters of the filename,
Add a code letter, for County it would be "C" and
Combine them, with an underscore character, to the contents of the name field and
Insert it into the geog_id field, replacing the word null,
so the new line looks like:

<sub_unit type="County" name="Campbell" geog_id="KYC_Campbell">

Any and all help greatly appreciated.

Try this:

Code:

awk -F'"' '
   NR==1 {
      OFS=FS;
      split(FILENAME, x, ".");
      prefix=toupper(x[1]) "C_";
   }
   /<sub_unit / {
      $6=prefix $4;
   }
   {
      print;
   }
' ky.abc.123.xml

Thanks Robotronic,
will give it a try on Monday at work.
I only have XP at home.
Will let you know how it turns out.


Thanks again.

Robotronic,

If I could bother you a bit more?
I pretty much understand what is going on, but there are a few areas that are still a bit murky.
If I am reading it right, the script breaks down as:

The -F '"' sets the field separator to a quote mark

The entire script is enclosed in a single quote or is it a back tick??

The NR==1 does ??

The OFS=FS; sets the Output Field separator equal to the Field separator or a quote mark.

The split(FILENAME, x, ".") sets the variable x with the first two character of the filename, using the . as field separator.

The prefix=toupper(x[1]) "c_"; sets the variable prefix to the contents of the variable x which has been converted to upper case and adds the "C_".

The /<sub_unit / { finds the lines to be modified???

$6=prefix $4; sets field 6 to the contents of the variable prefix and the contents of field number 4.

print sends it to output. Does it overwrite the existing xml or should it write to a temporary file and then move the temp to overwrite the original??

Again, thanks a million, I really appreciate the assistance.

awk scripts are always enclosed in single quotes.

The code in curly braces following this expression is executed only once, for the first loop (= for the first record of the input file = NR).

Quite right... "x" is an array which elements are all the dot-separated parts of the file name. So, x[1]="ky", x[2]="abc", and so on.

For every line that matches the pattern enclosed in slashes, executes the code which modifies the 6th field.

The output is sent to stdout, so your original file will not be overwrited: you need a temporary file as you said.

What am I doing wrong here?
First off, I'm using Cygwin on my XP to run the script, so that could be part of the problem.

I modified the script a bit and this works, from the command line,
but no matter how I tried, I could not get it to run from a script.

=================================
for i in ls *.xml; do
cat `$i` | awk -F'"' '
NR==1 {
OFS=FS;
split(FILENAME, x, ".");
prefix=toupper(x[1]"C_");
}
/[Cc][Oo][Uu][Nn][Tt][Yy]/ {
$6=prefix $4;
}
{
print
}'
done
=================================

The first problem, is it is not reading the FILENAME.
The x variable contains only a dash character and "C_".

The second problem is I can't re-direct the output.
I tried using:

/[Cc][Oo][Uu][Nn][Tt][Yy]/ {
$6=prefix $4;
}
{
print
}' > temp
done

but it won't work, it only creates an empty file, yet I can pipe it thru less and it displays to the screen.

/[Cc][Oo][Uu][Nn][Tt][Yy]/ {
$6=prefix $4;
}
{
print
}' | less
done

How can I get it to write to a file?

Thanks for any pointers.
All help appreciated.

Unfortunately I don't have Cygwin installed on my Windows system anymore, but I remember that when I was playing around with awk in a shell script I had the same issues, but I've never investigated too much for solving the problem.

Sorry, I can't help you.

Only to inform you that at least you're not alone