On Thursday 23 May 2002 09:56 pm, Paul D. Boyle reputedly wrote: > Under Unix (Linux) all processes automatically open three I/O streams, > stdin, stdout, stderr, these are often closed in a daemon process.
So, you need alternatives to these services. I make great use of the syslogger daemon. I had to become aware of the klogger, or kernel logger daemon because it would generate useful information for me. This led to needing an awareness of the logrotate function which led to needing an awareness of cron from a system point of view. I "tail -f" the /var/log/messages file for long periods of time and found that logrotate changes the file handles so that the "tail -f" goes dead so to speak. I've hacked a script that lets me quickly manage the tail function (script attached). I eventually learned how to manage the /etc/syslog.conf and syslog calls to define new log files associated with new facilities. Another capability that I think Brent Verner brought to my attention, and that I have not investigated yet, is the FIFO abilities of the Linux syslogger. More at "man syslogd". My daemons use AF_INET sockets for interprocess communication. I tried several flavors of IPC (SystemV, AF_UNIX sockets). And there are more IPC methods I did not try. I've seen code that used disk files for IPC. The Stevens book, "UNIX Network Programming, Volume 2, Second Edition: Interprocess Communications, Prentice Hall, 1999" was my primary resource. I use Python to write shell to daemon "communicators". My intent here is to dump a bunch of ideas to the list that you can pick through. If there is further interest, I can provide code detail and system configuration detail as requested. -- Mike Mueller www.ss7box.com
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