What process is starting dhcpcd?

[mariosangiorgio]

I have a quite standard Arch Linux setup. I installed it a few months ago on a Raspberry PI and I didn't changed much from the original system image.
I am a bit puzzled because I cannot figure out who is starting some of my services. For instance, I have both dhcpcd up and running (I see it in ps output and as I am connecting to the Raspberry PI through ssh and that machine gets an IP address through dhcp).
What is curious is that if I execute systemctl list-unit-files I get this output
$this->bbcode_second_pass_code('', '
mario@alarmpi> systemctl list-unit-files | grep dhcp
dhcpcd.service disabled
dhcpcd@.service disabled
')
That suggests that dhcpcp is not being started by systemd so I'm quite curious to learn who is actually starting it and to understand if this is the best setup.
Conversely, if I do the same thing for sshd it looks like it is actually managed by systemd, which increases my confusion about my configuration
$this->bbcode_second_pass_code('', '
[127] mario@alarmpi> systemctl list-unit-files | grep ssh
sshd.service enabled
sshd@.service static
sshdgenkeys.service static
sshd.socket disabled
')

[pepedog]

Network, it might be either netctl-ifplugd@eth0 or systemd-networkd@eth0 (both systemd, don't get confused), depending on how old image that was used

[mariosangiorgio]

Thanks, I suspected that dhcpcd was started by some other service.

There is just a thing that is not completely clear. Do netctl-ifplugd@eth0 or systemd-networkd@eth0 invoke the dhcpcd service beyond the scenes or do they simply start the daemon by themselves?

[krabat]

When netctl was default to handle the network the workflow was like so: netctl-ifplugd@eth0.service was enabled by a static (i. e. available without running systemctl enable) link in /etc/systemd/system/multi-user.wants. This service unit was launching ifplugd with /etc/ifplugd/netctl.action as argument of switch --run. Script netctl.action, which still is part of netctl, configured eth0 via netctl profile /etc/netctl/eth0 (not available any more) which in turn was launching dhcpcd.

systemd-networkd is not using dhcpcd at all but systemd's own DHCP client implementation.
The workflow with systemd-networkd is slightly easier, btw. systemd-networkd.service is enabled statically as described above and configuring eth0 via etc/systemd/network/eth0.network.

[WarheadsSE]

@krabat
That description of netctl-ifplugd is close, but not quite. The @eth0 is the interface name, not the profile name.

[pepedog]

I just noticed I added an @eth0 on the end of systemd-networkd, which is wrong

[krabat]

@WarheadsSE
But I didn't claim @eth0 was a profile!? The only thing I called a profile was file /etc/netcl/eth0 which is imo corresponding to the man page$this->bbcode_second_pass_quote('man (5) netctl.profile', 'P')rofiles for netctl live under /etc/netctl/ and are plain text files.