I think what OP meant was closer to "if it could have been entered into the bash history than there's other ways it could be seen".

Most CLI programs that need sensetive information as input should either do it interactively (a la sudo), as standard input, or configuration file. If worst comes to very worst, you can put the sensitive info in a text file and use backticks. For example:

  some-command --username=jedimastert --password=`cat secret.txt`