Re: [gentoo-dev] rfc: locations of binaries and separate /usr

[Alec Warner]

2012/1/5 Olivier Crête <tester@g.o>:
> On Fri, 2012-01-06 at 08:44 +0800, Patrick Lauer wrote:
>> On 01/06/12 05:26, Olivier Crête wrote:
>> [snip]
>> > The only thing I see them sacrificing is loose coupling, they provide
>> > more functionality than any other init system, more correctness
>> > (seriously, did you ever read most init scripts out there?), more well
>> > defined behavior (all systemd systems boot exactly the same), more
>> > stability (I'll claim that Lennart's C is better than any of the
>> > boot-time shell scripts I've seen) and well understandability depends
>> > who much you can understand C. Probably a bit less understandable for
>> > sysadmins, but since they can just play with config files, it's
>> > probably easier to understand in the end (and much less prone to
>> > breaking than mucking around shell scripts).
>> As you apparently have no idea what a sysadmin does I'd appreciate it if
>> people like you didn't try to guess what would make things better and
>> instead listened to people that have more than their desktop to run.
>> (Hint: It's not pressing reset buttons)
>
> I know what they do.. play in random scripts until whatever they're
> trying to hack together it seems to work, because oh well, its just a
> one time thing..  and then when stuff breaks they call Red Hat's support
> line.

Way to insult a large number of list members.

>
>> Given the choice between a single line of shell ( cat "$urandom_seed" >
>> /dev/urandom ) or 145 lines of undocumented C (which, if naively
>> modified by me, might just make systemd segfault) ... there is no choice.
>
> Actually, you don't have to do that, systemd does it for you and takes
> care of all the annoying details [1].
>
> That said, you can trivially disable systemd-random-seed-save.service
> and systemd-random-seed-load.service and instead write a unit file that
> runs whatever you want. You don't HAVE to do any C to run stuff from
> systemd, but it does provide many things written in C that are much more
> solid than the shell equivalents.
>
>> I do agree with you on one point - most init scripts are really bad
>> code, but that doesn't mean shell is bad, it means that you need to
>> educate people and file bugs. I've laughed at SLES' /etc/bashrc, I read
>> most of upstart and wondered how ... why ... is it can be drunk tiem?
>> Still that doesn't mean that rewriting it in bad C is in any way more
>> agreeable, and you just made debugging exquisitely painful. Yey.
>
> The big reason for C vs shell scripts is that the type of people who
> write them are not the same.. The type of people who write shell scripts
> tend to hack together stuff until it works. The people who write C tend
> to think about the problem for a long time and then write a complete
> solution that tries to take into account all of the possible error
> scenarios.

There are plenty of situations where shell scripts are entirely
appropriate. I am in agreement that most of the time initscripts are
not one of them. That being said I am not a fan of the tight coupling
here. Init is not supposed to segfault. A bug in one of the modules
may cause this to happen, so us old codger-y sysadmins (who apparently
love writing shell scripts and can't write real code to save our
lives) would much prefer some kind of separation. Perhaps keep 'init'
as a fairly simple codebase and run 'systemd' as pid 2 and they can
chat with each other (over dbus?)

-A

>
> [1] http://cgit.freedesktop.org/systemd/tree/src/random-seed.c
>
> --
> Olivier Crête
> tester@g.o
> Gentoo Developer