Not writing to log - but only when started from rc.local

Question

I have a simple C app running on both Ubuntu and Raspberry PI.

It need to write to a log file periodically and when run from the command line as root (or sudo) it creates / writes to the log file perfectly.

The log file is in /var/log/app-name/app-name.log (where app-name is the name of my app).

It first checks to see if the folder exists and if not then create it. It then opens the log file for create/append and outputs to it.

However, when I start the app from rc.local the app still does everything else perfectly, reading remote telnet servers, reads / writes to a local mysql database etc, but it never creates the /var/log folder or writes to the log file, even if it already exits (the fopen returns a 0).

I'm sure it's going to be something really simple, but I can't put my finger on it.

I've tried setuid etc and nothing has worked.

Any ideas?

Testing & creating the folder for the log goes like this. This works if run from the command line but failes when run from rc.local

void checkVarLogDir()
{
    struct stat st = {0};
    if (stat("/var/log/phone_log", &st) == -1) 
    {
        mkdir("/var/log/phone_log", 0744);
    }
}

Running from rc.local looking like this:

/path-to-app/phlog &

I could add the fopen/fwrite/fclose here as well but it's simple stuff that works when not run from rc.local.

post the code. How can we be expected to debug the problem with out the code? Are we to guess as to the code contents? It would also be a good idea to post the part of the script of `rc.local` that starts the application. — user3629249, Dec 31 '15 at 10:08
Put a `perror("/var/log/phone_log");` before and after the `mkdir` line and after `fopen` returns a 0, to let us know what errors occur. — Armali, Feb 14 '18 at 08:03

Not writing to log - but only when started from rc.local

0 Answers0