Re: [Help-bash] Why remove the export attribute of $_ every time after a simple command is executed

[ziyunfei]

On Sep 8, 2015, at 8:21 AM, Chet Ramey <address@hidden> wrote:
> 
> Because $_ has different meanings in different contexts.  It only expands
> to the final argument of a simple command when that command is executed,
> and that is passed to that command in its environment.  It also expands
> to the current mail file when checking for mail and is initialized (if not
> already set) to the name of the shell at shell startup.
> 

Thanks for replying, actually I know $_ has three different meanings depending 
on when and where it's used. but I just want to ask: what will happen if we 
allow $_ to be an environment variable when it represents the last arg, like 
ksh does.

$ echo 1
1
$ export | grep '_='
_=1
$ ksh --version
  version         sh (AT&T Research) 93u 2011-02-08