Equivalent key to alt+backspace on Linux
this functionality is provide by "readline", http://unixhelp.ed.ac.uk/CGI/man-cgi?readline+3. Most of keys are same as Emacs,


so, you can type control+w to delete the word just before the cursor
or for example,you can change the preferences of the terminal.app, use option as Meta key. Meta+Delete do the same thing