CODEWITHSUNDEEP
linuxshellawkmatchline
Daniela Calle
Daniela Calle

Reputation: 13

How to remove the lines which appear on file 1 from another file 2 KEEPING empty lines?

I know that in other questions you solve the first part of "How to remove the lines which appear on file 1 from another file 2" with: comm -23 file1 file2 and grep -Fvxf file1 file2

But in my case I have empty lines separating data sets that I need to keep, for example:

File 1:

A
B
C

D
E
F

G
H
I

File 2

A

D
F

I

what I want as a result:

B
C

E
    
G
H

The solution can be in bash or csh.

Thanks

Upvotes: 1

Views: 215

Answers (1)

RavinderSingh13
RavinderSingh13

Reputation: 133428

With awk please try following once.

awk 'FNR==NR{arr[$0];next} !NF || !($0 in arr)' file2 file1

Explanation: Adding detailed explanation for above code.

awk '                  ##Mentioning awk program from here.
FNR==NR{               ##Checking if FNR==NR which will be TRUE when file2 is being read.
  arr[$0]              ##Creating array with index of $2 here.
  next                 ##next will skip all further statements from here.
}
(!NF || !($0 in arr))  ##If line is empty OR not in arr then print it.
' file2 file1          ##Mentioning Input_file names here.

Upvotes: 2

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