Re: subshell (ctrl-o) not working properly

[Tomasz Chmielewski <mangoo wpkg org>]

Pavel Tsekov wrote:
> On Mon, 27 Feb 2006, Tomasz Chmielewski wrote:
>
> > Pavel Tsekov wrote:
> >
> > (...)
> >
> > > > Pressing ctrl + o shows the background, but I can't execute any shell
> > > > commands (I return to mc immediately when pressing any key).
> > > >
> > > >
> > > > Strace available at http://wpkg.org/subshell.strace.gz (strace -o
> > > > subshell.strace) and http://wpkg.org/sub.strace.gz (strace -o sub.strace
> > > > mc -U).
> > > The strace output suggests that the subshell is being killed by a SIGPWR
> > > signal. I cannot tell why this signal is being sent to the subshell
> > > though. Maybe the OS you are running on your embedded device is
> > > sending this signal for some specific purpose and expects the application
> > > to deal with it... In any case the fact that the subshell is not working
> > > on your platform is not a bug in MC.
> > Perhaps the subshell consumes so much resources on this tiny router that
> >   the kernel reports a power failure (that's what SIGPWR is) and kills
> > the subshell :)
>
> I cannot tell for sure but this doesn't seem to be the right signal for
> such scenarios ... The subshell process is just another shell (i.e. bash)
> so it consumes as much resources as your login shell.

Surely it's something else.
I'm running Samba + OpenLDAP on that + many other things, so this SIGPWR 
is perhaps a just bug somewhere (kernel? uClibc? bash? where?).


> > It's a regular Linux 2.4.30, a major difference is that it's not using
> > glibc, but uClibc, and not a x86 processor, but a mipsel one.
>
> Are you perhaps targetting an OpenWRT capable device ? If this is the case
> I might be able to get a shell access on an ASUS W500G device and try
> myself.

Indeed, I want to make mc running on OpenWRT, and it so happens, I'm 
running it on ASUS WL-500G (deluxe) box (with attached usb-stick).

There is no bash for OpenWRT, so I made it myself.

A bash binary for OpenWRT is available on 
http://www2.wpkg.org/openwrt/mc/ (together with two versions of mc - 
subshell-enabled and subshell-disabled).

If you want some other help (OpenWRT cross-compiling environment + 
explanation on how it works, OpenWRT shell access), let me know.


> > Not being a kernel hacker, this tells me that the only way to get
> > subshell working for me would be to make it ignore the SIGPWR I guess?
>
> It will help - yes. However there must be some reason for the signal being
> sent. I suggest you to try and find out what it might be.

Can it be that it's running glib-1.2? Perhaps not.


--
Tomasz Chmielewski
WPKG - http://wpkg.org
Software deployment with Samba