Issue with program executed by crontab

Question

I've coded a program in c for an embedded system (Devkit8000, which is a clone of the well known BeagleBoard) running Angstrom Linux.

The program creates a couple of threads, on of them is responsible of taking pictures with a camera connected to the board, and right now the second thread only moves that images to another path. The program should be running during the whole day, and the only way to stop it is sending a signal.

I edited the crontab to launch the program in a specific hour and to send a signal when it has to stop, the issue is that launching the program in this way cause the process to be killed after some time running, but, if i launch the program manually (through the command line), it works perfectly and dont get stopped.

I have no idea about the reason of this different behaviour between crontab and command line. I've checked the system logs but didnt find anything useful. I've also been reading a little and find that the OS can kill a process if it is using so much resources, but doesnt make sense that this happens in only 1 scenario (crontab vs manually)...

Any clue about what is happening?

Thank you in advance!

Answer 1

The main difference is that running a job through cron invokes a non-interactive non-login shell. The effect of that depends on the default shell for your user. For example, if you are using Korn shell or Bash then your .profile will not be executed, as it would on an interactive login shell. Korn shell 88 will execute .kshrc (the $ENV file) but ksh93 will not. So, a good start might be to call your program from a script, after first "sourcing" your .profile file:

. $HOME/.profile

Failing that... When you say that the process is "killed", do you get such a message? If so, then that sounds like someone sending SIGKILL, ie kill -9 . If not, then maybe you could run strace or ltrace to find out at what point it dies.