applying awk on multiply folder and subfiles

Question

I have 10 folders with consecutives name : book_1, book_2..... book_10 and each folder has a txt file named same as the folder. For example : book_1 has only book_1.txt and contains history material (only text).

I need to run an AWK script which output should be added by order to the output file. How can I generate a loop which runs through my folders and extractes the needed file from each folder?

awk '
    {
        script//
    }
    END { print "The output of book num $i is:  " m }' book*/book*.txt >> output.txt // m is a variable which extracts max occurences of certain words which are set in the script

My output should look like this:

The output of book num 1 is : 123
The output of book num 2 is : 2223

and so on

thank you for your help!

Answer 1

The simple way using any awk in a shell that supports the {1..10} construct for generating a range of numbers (otherwise just use $(seq 10)) is:

for i in {1..10}; do
    awk -v i="$i" '
        {
            script//
        }
        END { printf "The output of book num %d is : %d\n", i, m }
    ' "book_${i}/book_${i}.txt"
done > output.txt

but if you really wanted to do it all in awk it'd be (using GNU awk for ARGIND and ENDFILE):

awk '
    BEGIN {
        for (i=1; i<=10; i++) {
            ARGV[ARGC] = "book_" i "/book_" i ".txt"
            ARGC++
        }
    }
    {
        script//
    }
    ENDFILE { printf "The output of book num %d is : %d\n", ARGIND, m; m=0 }
'  > output.txt

If any of the "book" files can not exist then you'd need to add some protection against that.