subshell (ctrl-o) not working properly

[Tomasz Chmielewski]

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