[svlug] Complicated logs rotation under cron and date format in Linux/Unix
raffi at linwin.com
Mon Oct 29 09:52:02 PST 2001
On Mon, Oct 29, 2001 at 12:57:59AM -0800, Nate Campi wrote:
> On Mon, Oct 29, 2001 at 12:24:42AM -0800, Rafael Skodlar wrote:
> > > > I was under the impression (maybe it was some versions of Unix from years
> > > > ago?) that HUP makes the system read the program and configs again. That's
> > > > definately not the case with Linux since I tested that a few moments ago.
> > > This has nothing to do with UNIX or Linux (the kernel) and everything to
> > > do with the app, and what it does when it receives the SIGHUP signal.
> > > This is entirely app dependent. It's simply a convention that SIGHUP
> > > means 're-read config files without restarting process', not a rule.
> > By the program I meant system daemons that are supposed to follow POSIX if
> > I'm not mistaken.
> > SIGACTION(2) Linux Programmer's Manual SIGACTION(2)
> > Apps can do whatever they want and not necessarily follow POSIX.
> Correct, the sigaction function is the POSIX way to establish the
> disposition of a signal. Are you saying that POSIX dictates what a
> process is to do when it receives certain signals? I honestly don't know
> either way.
> It seemed to me that you had a fundamental misunderstanding of what
That's possible. World is dynamic and what means understanding today might
not be the same tomorrow. We can learn new things every day as long as we
don't wear burka.
> is supposed to happen when you send SIGHUP to a process. The fact is
> that unless the program does something special to catch it, most signals
> cause a process to die (exceptions are SIGCHLD and SIGURG). Whether or
> not POSIX says what a process is to do upon the reciept of certain
> signals, the fact is that in application there are no hard and fast
> rules, only conventions.
Things have a history of evolution. Linux was not POSIX compliant from the
begining. I don't know if that depends on the distribution more than on
the kernel. Man pages mention sigvec in BSD, sigaction in POSIX for
example and not being familiar with either one in detail I can't tell the
Similarily RFCs. Did some reading on RFCs related to email over the
weekend. A lot of room for interpretation.
> Nate Campi, UNIX Ops WiReD SF, Terra Lycos DNS, (415) 276-8678
By the way, Sys Admin magazine (Nov 2001) has an article about using NIS
to control crontabs on servers and workstations. Beats individual settings
in /etc/cron* When you have a bunch of users with laptops going in and out
of your network domain and need to run common cron jobs. Central
administration = productivity.
++ Rafael Skodlar
++ Knowledge is power, tell me more
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