tr output to new lines

Question

I am trying to remove all non-alphanumeric from a text file with the following command:

cat textfile.txt | tr -cd [:alnum:] > textfile_alnum.txt

This works, except that now the output within textfile_alnum.txt is all on the same line. How can I maintain each string on a separate line?

Answer 1

If you want new lines from the original file to be preserved, use the following:

tr -cd [:alnum:]'\n'

This adds the new line character (\n) to the set of characters that you want to keep.