Meaning/usage of $_ in bash

[Michael ODonnell]

> The _ variable appears to be overloaded...  with different meanings
> in different circumstances.  Qutoing the bash man page:
>
> _ At shell startup, set to the absolute file name of the shell
>   or shell script being executed as passed in the argument list.
>   Subsequently, expands to the last argument to the previous com-
>   mand, after expansion.


D'oh!!!  I claim I RTFM but I guess not carefully enough...