CODEWITHSUNDEEP
linuxbashshellunix
David
David

Reputation: 3105

Shell nested for loop and string comparison

I have two files file1

104.128.225.208:8000
103.27.24.114:80
104.128.225.208:8000

and file2

103.27.24.114:99999999
103.27.24.114:88888888888
104.128.225.208:8000
103.27.24.114:80
104.128.225.208:8000

and in file2 there are two new lines

103.27.24.114:99999999
103.27.24.114:88888888888

So I want to check if there are new lines in file

for i in $(cat $2)
    do
        for j in $(cat $1)
        do
            if [ $i = $j ]; then
                echo $i
            fi
        done
    done

/.program file1 file2

but I don't get expected output. I think that my if statement is not working fine. What I'm doing wrong?

Upvotes: 0

Views: 233

Answers (3)

zwol
zwol

Reputation: 140748

Your problem is probably that you are looping over every line in file1 for each line in file2.

The comm utility does what you want, but it assumes both files are sorted.

$ sort file1 -o file1
$ sort file2 -o file2
$ comm -13 file1 file2
103.27.24.114:99999999
103.27.24.114:88888888888

Upvotes: 3

David C. Rankin
David C. Rankin

Reputation: 84579

This is what diff is for. Example:

$ diff dat/newdat1.txt dat/newdat2.txt
0a1,2
> 103.27.24.114:99999999
> 103.27.24.114:88888888888

Where newdat1.txt and newdat2.txt are:

104.128.225.208:8000
103.27.24.114:80
104.128.225.208:8000

and

103.27.24.114:99999999
103.27.24.114:88888888888
104.128.225.208:8000
103.27.24.114:80
104.128.225.208:8000

You can simply test the return of diff with or without output depending on the options and your needs. (e.g. if diff -q $file1 $file2 >/dev/null; then echo same; else echo differ; fi)

Upvotes: 1

clearlight
clearlight

Reputation: 12625

#!/bin/bash
for n in $(diff file1 file2); do 
   if [ -z "$firstLineDiscarded" ]; then
       firstLineDiscarded=TRUE
   elif [ $n != ">" ]; then 
      echo $n
  fi
done

If you're not attached to that particular approach this seems to work.

Of course it breaks down if the input syntax changes (includes spaces in the data), but for this strict application... maybe good enough.

Upvotes: 0

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