Shell Programming and Scripting

the objective is to get '20070809141159 Ack_to_MDS_20070809141159.xml' out of 'Ack_to_MDS_20070809141159.xml'; sort the file names; remove '20070809141159' (in our case) the prefix leaving the 'suffix' (the file name itself) - this will give us the sorted list of files based on the embedded timestamp.

What's the 'embedded timestamp' in the file name? The 'embedded timestamp' if the next to the last field in the '_' OR '.' filename.
'nawk' takes the next to the last field of all the wild-carded filenames and makes the timestamp from the filename a 'prefix' followed by the value of 'OFS' (space) followed by the $0 (filename).
we sort numerically '-n' - having the timestamp appearing as a prefix, make the sort work as expect.
once sorted, we remove the 'prefix' (timestamp) with the 'cut' command.
The end result is a list of file names sorted by the embedded timestamp.

And the rest is our editting/grepping body of the loop.

Hi Guys

Thanks for all the pointers and help.
Got a simple and quick one liner answer.

Code:

 ls -1rt Ack_to_MDS_* | xargs cat > new_file.xml

Regards
Srikanth GR

this assumes that your OS file timestamps are the same as the timestamps embedded in your file names - that was not your initial requirement.

Code:

#!/bin/sh

awk 'BEGIN{i=0}
{   filename=FILENAME
    gsub("Ack_to_MDS_|.xml","",filename); 
    year=substr(filename,1,4)
    mth=substr(filename,5,2)
    day=substr(filename,7,2)
    hr=substr(filename,9,2)
    min=substr(filename,11,2)
    sec=substr(filename,13,2)
    t = mktime(year" "mth" "day" "hr" "min" "sec )
    array[t]=FILENAME
    nextfile
}
END{
    n=asort(array)
    print "<ACKNOWLEDGEMENTS>" > "newfile"
    for(i=1;i<=n;i++) {
	file=array[i]
	while(  (getline line < file ) >0 ) {
	    if ( line ~ /<ACKNOWLEDGEMENTS>/ || line ~ /<\/ACKNOWLEDGEMENTS>/ ) {
		continue
	    }
	    else {
	        print line > "newfile"
	    }	
	}
		
    }
    print "</ACKNOWLEDGEMENTS>" > "newfile"
}' Ack_to_MDS_*.xml

ghostdog74,
this is GNU gawk specific - no need for 'mktime' - you already have a 'sortable' timestamp presentation/format.

my bad. i didn't read the posts properly. thanks
Anyway, the requirement doesn't seem right. The one liner doesn't solve the part where he doesn't need the <ACKNOWLEDGEMENTS> and </ACKNOWLEDGEMENTS> (or does it?)

the OP seems to be gone: no OP - no problem!

BTW, no need for 'mktime' - you already have a 'sortable' timestamp presentation/format.