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Re: daemons -- who needs'em?



** On Apr 27, w trillich scribbled:
> ever wonder what all those background processes are for?
> 
> me too, and i still do. if you have some answers, please
> post them for us newbies.
> 
> # ps t\?
>   PID TTY      STAT   TIME COMMAND
>     1 ?        S      0:06 init [2]
parent of all the processes in your system.
                        
>     2 ?        SW     0:00 [kflushd]
Not a "real" process - a kernel flush daemon (actually a kernel thread)
Runs periodically to flush the block device buffers

>     3 ?        SW<    0:00 [kswapd]
Same as above, but for the swap activities. Synchronizes swap information.

>     4 ?        SW     0:00 [md_thread]
>     5 ?        SW     0:00 [md_thread]
You probably don't need these two. They're auto-mounter threads AFAIR

>  9757 ?        S      0:00 /usr/sbin/apache
Your HTTP server.

>  1319 ?        S      0:01 update
On newer kernels it's not needed anymore. Performs the same function (more
or less) as the above k*d daemons.

>  1885 ?        S      0:00 /sbin/syslogd
System logger. Writes to files what applications send to the system log.

>  1887 ?        S      0:00 /sbin/klogd
A partner to the above daemon which takes care of the kernel logging.

>  1894 ?        S      0:00 /sbin/kerneld
Daemon to load the modules on demand. In newer kernels not needed anymore.

>  1897 ?        S      0:01 /usr/sbin/named
Nameserver (a DNS server) - in that case it's BIND

>  1918 ?        S      0:00 /usr/sbin/exim -bd -q30m
Your MTA (Mail Transport Agent) or, in M$ nomenclature, an SMTP server

>  2002 ?        S      0:00 /usr/sbin/rwhod
RPC-based remote who server.

>  2001 ?        S      0:00 /usr/sbin/rinetd
A version of inetd that redirects requests somewhere else than this machine.

>  2018 ?        S      0:00 /usr/sbin/afpd -n server
>  2020 ?        S      0:00 /usr/sbin/papd
Don't know these two :))

>  2026 ?        S      0:00 proftpd (accepting connections)
ProFTPD ftp server running in standalone mode

>  2031 ?        S      0:00 /usr/sbin/atd
Scheduled job spooler (for the 'at' command)

>  9758 ?        S      0:00 /usr/sbin/apache
>  9756 ?        S      0:01 /usr/sbin/apache
>  9759 ?        S      0:00 /usr/sbin/apache
>  9760 ?        S      0:00 /usr/sbin/apache
>  9761 ?        S      0:00 /usr/sbin/apache
Clones of the parent (above) HTTPD process. Apache is a multi-process
architecture server.

>  2206 ?        S      0:00 /sbin/portmap
Portmapper for the RPC-based services (kinda a dispatch for them)

>  2215 ?        S      0:00 /usr/sbin/inetd
The "normal" internet superserver. It takes care of starting your services
that aren't ran in the standalone mode.

>  5922 ?        S      0:00 /usr/sbin/cron
A cronjob server. Something like a scheduler but a periodic one, unlike atd
which executes something 'at point' - once.

[snip]
> inetd = listens for network connections & hands them off 
>   to appropriate processes
> proftpd = ftp server
> apache = httpd server
> named = dns nameserver (xlate 'www.site.org' to '123.45.678.90')
> exim = email stuff
> cron = periodic script-runner (try "crontab -e")
> atd = like cron; but for running scheduled 'at <time>' commands
> update = flushes disk buffers now & then so if ever you crash
>   (remember windows? macos?) you'll lose less.
> 
> these i can GUESS at:
> 
> *logd = system loggers:
>   syslogd and klogd both log important messages to your log files.
>   we need them _both_ because... well... um...
Because syslogd handles the userspace messages, klogd handles the kernel
messages.

> kerneld = linux 2.0 and earlier--some voodoo regarding modules
>   (dynamic module loading in 2.1+ [aka 'kmod'] makes this obsolete?)
yup

> rwhod = server for 'whois bubba@edu.org.com'
useless crap (IMHO)

> rinetd = like inetd, but different?
nah, a redirector - do you really need it?

> afpd = portion of appletalk network protocols, maybe?
> papd = some more appletalk stuff?
hmm, dunno, perhaps? :)

> portmap = something to do with Remote-Procedure-Call?
precisely

marek

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