Redirecting tr stdout to a file [closed]

view story

http://unix.stackexchange.com – Possible Duplicate: How can I make iconv replace the input file with the converted output? Can I read and write to the same file in Linux without overwriting it? $ cat test.txt This is a test file. $ tr 'a' 'z' < test.txt This is z test file. $ tr 'a' 'z' < test.txt > test.txt $ cat test.txt $ Why does tr seem to output nothing to test.txt? I found this thread, but I don't really understand what is going on, and how to fix the problem. (Also, the reason I'm not using sed is because I want to replace newlines with another character, and I don't think sed can operate (HowTos)