linux shell get multi file intersection - linux

Question

I have a few txt file examples 1.txt 2.txt 3.txt 4.txt
I want to get 1.txt 2.txt 3.txt 4.txt content intersection
cat 1.txt 2.txt | sort | uniq -c > tmp.txt
cat tmp.txt 3.txt | sort | uniq -c > tmp2.txt
and so on ....
Is there a better way?
input text
1.txt
1
2
3
4
2.txt
1
2
3
3.txt
1
2
4.txt
1
5
expected output:
1

Answer 1

With your shown samples please try following awk code.
1st solution: This considers that you may have duplicates values of lines with in a single Input_file itself then you may try following:
awk '
!arr2[FILENAME,$0]++{
arr1[$0]++
}
END{
for(i in arr1){
if(arr1[i]==(ARGC-1)){
print i
}
}
}
' *.txt
2nd solution: This solution assumes that there is no duplicates in Input_file if this is the case then try following:
awk '
{
arr[$0]++
}
END{
for(i in arr){
if(arr[i]==(ARGC-1)){
print i
}
}
}
' *.txt
Explanation: Adding detailed explanation for above.
awk ' ##Starting awk program from here.
{
arr[$0]++ ##Creating an array named arr with index of $0 and keep increasing its value.
}
END{ ##Starting END block of this program from here.
for(i in arr){ ##Traversing through array arr here.
if(arr[i]==(ARGC-1)){ ##Checking condition if value of current item in arr is Equal to total number of files then print it.
print i
}
}
}
' *.txt ##Passing all .txt files as an input to awk program from here.