[PATCH] ash: add support for history buffer

[Denys Vlasenko]

On Wednesday 13 July 2011 15:43, Dennis Groenen wrote:
> On 07/13/2011 03:13 PM, Laurent Bercot wrote:
> >   Specialized filesystems such as jffs2 or yaffs2 still can, however.
> Good point, but a lot of, for example closed, embedded/mobile devices 
> require a lot of hacking around to get something custom (like a 
> different fs) running.
> >   Why shouldn't it be? Either you want to reduce the number of writes
> > to the filesystem, or you don't. Delayed writing, which is configured
> > at the filesystem layer, accomplishes this for every application without
> > the need for patching. Applications can always fsync() when they need
> > synchronous writes.
> True, but generally those writes from other applications are going to 
> happen anyway. E.g. if I save a file in application X, it will need to 
> be written out, and be written out completely. For BusyBox's history, 
> this isn't the case. I don't see why a file has to be written out after 
> each appended line here. Vi doesn't write out a file after each new line 
> either, does it?

sh can crash.
sh can be killed by a signal.
sh can be run in parallel from two terminals, and saving at exit creates
unfairness: whoever exits last overwrites the history of other guys.

Nevertheless, I am not firmly against saving only on exit.
Actually, I think that's the option you'd like.
So, (1) it would largely solve your problem
and (2) it would also be welcomed by people who like
more bash-like behavior wrt history saving.

Can you code up a patch which does this?

-- 
vda