When I type pppd I get "command not found" error
I checked in usr/sbin/ and it's exist and can be activated by typing the full path but when typing the command alone it doesn't work I get the same error for ifdown, ifup, netconfig and many more how can I fix it?
I have redhat Linux 9

I think that the command that you are looking for is either kppp or wvdial depending on how Red Hat set up your internet connection.

As root?

if you are running bash, you can add /usr/sbin
to your path in ~/.bash_profile or /etc/profile

ppp_d_ is a daemon. Normally it should be loaded by the application that needs it (like wvdial or clicking the connector-symbol in KDE).

Try modprobe (?) or any other commands of your preference to find out what processes are loaded and / or running to make sure that pppd is the real problem.

Or even 'pon'

I just remembered: daemons (modules) might also be kicked off by "insmod", which, as I understand it, loads it into the kernel. I'm am not sure whether the pppd can be started the way you tried to do it.

Daemons and modules are not the same thing or even similar. Insmod doesnt start deamons it loads modules.
You could start a ppp connection from the commandline if you wanted to and you had chat and had done "modprobe -v ppp" first:

pppd connect 'chat -v "" AT OK ATDT5551212 ~' -detach lock modem crtscts asyncmap 00000000 defaultroute usepeerdns user username remotename ppp0 debug /dev/modem 115200 ipparam ppp0 linkname ppp0 call ppp0 noauth

or something similar would do it.

Wvdial is a pretty painless way to set up a ppp connection. If you have it you might want to give it a look.

@m0rl0ck: Thanks for this clarification. I thought that ppp_d_ is a driver (in the Windows sense ) and thus would have to be "inserted".

Just for the record, what is the difference between modules and daemons then? Am I correct, that ppp is a program which then starts pppd (just like wvdial)?

A module is a program. A daemon is a logical entity which runs independently of other daemons. While processing, a daemon can wander through many programs.

Logical entity Whats that?
(Can't be a human )

A daemon is an independently running process that has its own set of resources. Each daemon has a number which is the PID. Daemons run independently of each other. That is how you can have several programs running simultaneously. Actually it is several daemons running simultaneously.

a module usually means a kernel module, very similar
what you think of in windows as a driver.
they are in /lib/modules/$kernelversion/

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Am I correct, that ppp is a program which then starts pppd (just like wvdial)?
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When you start wvdial you start a daemon which runs the wvdial program. wvdial starts a daemon called pppd which runs a program called ppp. My wvdial log always gives the PID of pppd. ppp is a module that is part of the kernel. pppd accepts requests from other daemons running web browsers like Mozilla and/or email programs like sylpheed and/or ftp clients like gftp. pppd accesses the internet for all the other daemons and keeps track of what information is to be passed to which daemon.

Some kernel modules are transient and some are a permanent part of the kernel. I think that ppp is partially permanent and partially transient.

@jailbait

Let me see, whether I understand correctly:

Each and every "program" has a controlling daemon, like an envelope (your erstwhile logical entity), which controls the program's execution. These envelopes can be nested (in your example: daemon[wvdial[pppd(aemon)[ppp]]], while communication between ppp(d) and other applications is running. That correct?

If so, then why is pppd contacting the Internet enstead of ppp (I mean with pppd being only the controlling entity)? I thought ppp has the rights to write to the modem?

Since there is also a daemon running e.g. Mozilla, I take it, that the daemons are really interprocess-communications facilities (like semaphores)?

@whansard:
Thanks for the pointer to where the modules can be found.