Question

How it is possible to make a dry run with sed?

I have this command:

find ./ -type f | xargs sed -i 's/string1/string2/g'

But before I really substitute in all the files, i want to check what it WOULD substitute. Copying the whole directory structure to check is no option!

Answer 1

Remove the -i and pipe it to less to paginate though the results. Alternatively, you can redirect the whole thing to one large file by removing the -i and appending > dryrun.out

I should note that this script of yours will fail miserably with files that contain spaces in their name or other nefarious characters like newlines or whatnot. A better way to do it would be:

while IFS= read -r -d $'\0' file; do
  sed -i 's/string1/string2/g' "$file"
done < <(find ./ -type f -print0)