将txt文件中的每一行与每一行中的另一个文本文件进行比较

Question

i'm having some difficulties about shell script these days. Done some test and still can't make it work. I'm trying to compare each line in a text file to another text file. The idea is to see if some line is not in the file2.

Could someone see what is wrong on my script ?

Thanks!!

#!/bin/bash
  FILE1='/filePath/file.txt'
  FILE2='/filePath/file2.txt'
  for line in $FILE1 
  do
    for line2 in $FILE2
    do
        if  $line != $line2
            then
            echo -e /> diffsScr.txt
        fi
    done 
  done

Answer 1

awk 'FNR==NR{f[$0]+=1; next} !($0 in f)' input1 input2

This reads through the file input1 and builds an array. Then it goes through input2 and prints each line that did not appear in input1 . If you want to add line numbers:

awk 'FNR==NR{f[$0]+=1; next} !($0 in f) { print FNR, $0}' input1 input2

One big advantage of this approach is that it scales well. Your approach is O(n*m) where n and m are the number of lines in the files, but pre-reading into a array like this gives you a solution that is O(n+m). In other words, you only read through each file once.

Answer 2

您可以使用以下命令实现此结果：

fgrep -v -x -f '/filePath/file2.txt' '/filePath/file1.txt'

Answer 3

If your files are sorted, you can use comm to compare files.

comm -23 file1 file2  

Description of comm:

   Compare sorted files FILE1 and FILE2 line by line.

   With  no  options,  produce  three-column  output.  Column one contains
   lines unique to FILE1, column two contains lines unique to  FILE2,  and
   column three contains lines common to both files.

   -1     suppress column 1 (lines unique to FILE1)

   -2     suppress column 2 (lines unique to FILE2)

   -3     suppress column 3 (lines that appear in both files)