Arch Linux

From what I google older versions of udev used to clear the $PATH environment variable but not anymore.

Since /etc/profile is sourced after the boot-up process, it doesn't affect the $PATH that udev inherits.

I see two ways to modify the $PATH udev inherits:

in /etc/rc.sysinit (and possibly also in rc.single) call udev as
PATH="..." /sbin/udevd --daemon
^ does this need to be prefixed with "export"?

in /lib/udev/rules.d/ add a rule "00-paths.rule" containing
ACTION=="*", ENV{PATH}="..."


First to consider: is it a good idea to change udev's $PATH? If so, is it preferable to set the $PATH correctly for all applications in /etc/rc.sysinit, or only for udev? (this would render /etc/profile a bit redundant)

That's not only a udev problem. Everything started by initscripts inherits a default path, one which doesn't include {/usr,}/sbin for example. This has not caused any problems so far.

Actually, I wouldn't say that it is incomplete. It's just unexpected.

Which scripts, in particular, are failing here? Just use the full path and everything works fine.

There is no single unified place to define the system PATH. It's based on the shell

Unexpected means non-standard. I believe Arch is the only major distribution (Ubuntu - Debian - Fedora) required to patch helper programs called by udev rules to include the full path.

For example - possibly the only example - the gpsd helper program "/lib/udev/gpsd.hotplug" needs modification.

Line 49 @ http://repos.archlinux.org/wsvn/community/gpsd/trunk/PKGBUILD
sed -i 's|gpsdcmd = "gpsd %s|gpsdcmd = "/usr/sbin/gpsd %s|' gpsd.hotplug

What you are seeing IS, in fact, bash's default path. That's about as standard as it gets.

The reason bash is using its default path is that it is started non-interactively without a parent process giving it a PATH.

How do we change this? No idea. Please look into how the other distros you referenced do it. My guess is that they set BASH_ENV, or perhaps even export PATH before calling init for the first time.

I believe PATH is inherited from the parent, and a non-interactive shell does not replace it.

Right but the parent, in this case is init... does init inherit it from the initramfs code?

The parent is actually rc.sysinit.

So do we want to just set PATH in rc.sysinit? It seems a little hokey, but I guess it's not THAT bad.

decision?

Could you try this patch: <https://github.com/teg/initscripts-arch/commit/aa947f924e273a37fd1492b14be1fad2d540979d>?

Let me know if there is a problem. If it does not work it is a bug in either systemd or udev (or the provider of the helper script), which I'd like to file upstream.

If we adopt a default path in rc.sysinit, we should be consistent - we do not include /usr/local/{s,}bin in any default paths so far (there was a discussion which surprisingly moved towards not including /local/ by default for weird reasons).

@brain0: Maybe I'm confusing myself, but my patch adds the same PATH to rc.sysinit as is set in /etc/profile from "filesystem", is that not the standard one?

I just looked, and it seems my memory was playing tricks on me.