How to know what to

Im using awk, and want to send in an arbitrary number of text files (arguments) into my script, and for each input file "print something".

I have found the script here

And modified the script into this

awk -v nfiles="10" 'NR==FNR{a[$0]++;next}
$0 in a {a[$0]++; next}
{b[$0]++}
END{
  for(i in a){
    if(a[i]==nfiles) {
      print i > "output1"
    }
    else if(a[i]==1) {
        print i > "output3"
    }
  }
  for(i开发者_运维问答 in b){
    if(b[i]==nfiles-1) {
        print i > "output2"
    }
  }
}' "$@"

Problem is what do I write in nfiles="10" since its supposed to be arbitrary number of text arguments?

Also I quite don't understand this script, it only executes this section

 else if(a[i]==1) {
        print i > "output3"
    }

And only prints out the information from file1.txt. Why don't it executes the rest, and what if I would like to print out everything in row 3 ($3) from all files into output3? Thanks =)

If you want to print the third column $3 of every file into a single output file, you could use something like this:

awk '{ print $3 }' file1 [file2 .. filen] > output3

If you want to print the third line of every file:

awk 'FNR == 3' file1 [file2 .. filen] > output3

You can, of course, use glob to match your files:

awk '{ print $3 }' common_pattern* > output3

Instead of passing nfiles=10 add this to your awk script as the first action.

FNR==1 {nfiles++}

Use to calculate the number of files added:

awk 'BEGIN {nfiles = ARGC-1}
...
}' "$@"