mjhjmtu

I have used the code cat *.txt >> output.txt . This code is doing is its work but here unix is deciding the order in which the files are being copied to my output file which is undesirable as i want the files to be copied according to their occurence or time of generation .
I have also used the below command so i can control the copy format

for tablename in 'cat $current_path/table.txt(have defined the order)

do 

for data in 'cat path/$tablename.txt

do 
echo "$data" >> final/output.txt

done

done 

here it is doing its work but generating multiple copies of the single txt as for loop is working .

Assuming I understand the question then

 xargs < "$current_path/table.txt" cat > final/output.txt

is all you need. xargs will read the "table.txt" file and run cat with the files in the specified order, so will output them to stdout, and you redirect stdout to the desired place. Note that this works even if there are so many files that xargs executes cat more than once, as the redirection is done only once before any cat (or even the xargs) is executed.

If you want it sorted according to time, then

 ls -t | xargs cat > final/output

will work if there are no awkward filenames (e.g. embedded spaces or newlines).

for tablename in $(cat $current_path/table.txt);do
 for word in $(cat path/$tablename.txt);do
 echo $word
 done
done > final/output.txt

This should work. I'm not sure what you mean by

here it is doing its work but generating multiple copies of the single txt as for loop is working

Can you be more specific ?

-- Edited -- following the suggestion below.