I'm trying to run pppd on an embedded machine and the application terminates immediately with no message, warning, or anything. It doesn't seem to have any print option and I'm scratching my head trying to find a clue as to why it did not want to run. I have a few suspicions as to why but I need evidence to confirm them. Is there any alternative means for determining why a program exited abruptly? I've tried looking at dmesg and saw nothing there.

I should also mention that this embedded system is very minimal (no build environment) and any software I install on it has to be cross compiled from another machine and the files copied over by hand. (I had to do this to put pppd on the system in the first place). Thanks for any advice you can give.

You should be able to ssh into it from another computer. Once there, run the program from the command prompt and note the output. I don't know what kind of device it is and I'm hoping that you can set-up some sort of ssh or connection between a PC and the device via USB or network. I apologize in advanced if this is just not possible, but it should be.

Check the error code it returns:
# pppd ......
# echo $?

If you've got strace on there, try running pppd through that to see what it's up to:
# strace pppd ......

Dave

Unfortunately no I don't have ssh access. The exit code pppd returns is 1 so its definitely not happy. Unfortunately no I don't have strace on this machine. I just had the idea to write the standard output and error to two files to see if it said something.

stderr.txt was empty, but the other file had a useful message:

"Couldn't set tty to PPP discipline: Invalid argument"


So hopefully that clue will help me find the problem. Thanks for the help guys.

You should make sure that your kernel supports PPPOE, PPPOX and PPP_ASYNC. If they are compiled as modules, make sure they are loaded.

Yeah that was the problem. I only had half of the kernel modules I needed loaded. Once I loaded the other two everything worked just fine.