How to compare two arrays of text files in bash script?

Question

I am trying to compare two arrays of text files. I keep getting this error

./CompareScript.sh: line 11: read: `../Results/result1.txt[@]': not a valid identifier

Not sure how to properly do this

#!/bin/bash
results=(../Results/*.txt)
correct=(../Correct/*.txt)
j=0
for i in "$results"
do
   while read -r $results[$j]; do
     while read  -r $correct[$j];do
        if [$results[$j]==$correct[$j]] ;  then
          echo "two files are same"
        else
          echo "two files content different"
        fi
     done
   done
   let "j += 1"
done

Answer 1

It is rather unclear what you are trying to achieve. If the directories Results and Correct contain matching file names, then you can loop over one of them and generate the other paths:

#!/bin/bash
results=(../Results/*.txt)

for r in "${results[@]}"; do
  diff -sq "$r" "${r/\/Results\//\/Correct\/}"
done

If you want to cross-compare all files from Results with all files form Correct, then that would be a case for nested loops.

#!/bin/bash
results=(../Results/*.txt)
correct=(../Correct/*.txt)

for r in "${results[@]}"; do
  for c in "${correct[@]}"; do
    diff -sq "$r" "$c"
  done
done

A few rather obvious syntax errors:

• for i in "$results"
  → for i in "${results[@]}" to iterate over values
  → for i in "${!results[@]}" to iterate over indices
• $results[$j] → "${results[j]}"
• [$results[$j]==$correct[$j]] → [[ "${results[j]}" == "${correct[j]}" ]]
• not exactly an error, but… let "j += 1" → ((++j))
  — More importantly, your use of i (none at all) and j does not make much sense.
• to actually read and process a file, line-by-line:

  while IFS= read -r line; do
    printf '%s\n' "$line"
    some_other_command "$line"
  done < "${results[i]}"  # for example
  

  • But why do that↑? If you want to compare files, let diff do it.