$ cat test.file | tr -cs A-Za-z '\n' | tr A-Z a-z > diffFirst $ cat test.file | tr A-Z a-z | tr -cs a-z '\n' > diffSecond $ diff diffFirst diffSecond $ No d

$ cat test.file | tr -cs A-Za-z '\n' | tr A-Z a-z > diffFirst $ cat test.file | tr A-Z a-z | tr -cs a-z '\n' > diffSecond $ diff diffFirst diffSecond $ No differences with my test file.