'cat' can be harmful..

'cat' can be harmful at times. some people might have lost the data because of improper usage of cat command like cat > filename.txt, or it can do over write some existing files data without prompting the user.
to get rid out of these situations

1. open the terminal

2. execute " set -o noclobber "

that's it. now next time when cat tries to over write the existing file it will prompt the user.