Q: executables in /lib/udev , is this correct?

Valter Douglas Lisbôa Jr. douglas at trenix.com.br
Sat Aug 23 07:32:38 PDT 2008

Em Friday 22 August 2008 19:24:12 Jeremy Henty escreveu:
> On Fri, Aug 22, 2008 at 03:31:36PM -0300, Valter Douglas Lisbôa Jr. wrote:
> > Em Thursday 21 August 2008 14:51:12 Jeremy Henty escreveu:
> > > I  just noticed that  both my  LFS 6.1  and 6.3  systems installed
> > > useful  executables  such as  vol_id  into  /lib/udev rather  than
> > > anywhere in my $PATH .
> >
> > This executables is  not need to be in the PATH,  they are called by
> > udev tools in background.  They Follow the /usr/lib/<program>/* idea
> > to  separate  libraries,  backstage  daemons, whatever  from  system
> > aplications runned in terminals,
> I understand  what you say,  but I expected something  different after
> reading a good article "How To Manage Your Disk By UUID On Linux"
> http://linuxshellaccount.blogspot.com/2008/08/how-to-manage-your-disk-by-uu
> which says things like
>     1. If  you don't know the  UUID of your  disk, you can find  it by
>     using one of the several commands below:
>     host # vol_id /dev/sda3
>     ...
>     ID_FS_UUID=a1331d73-d640-4bac-97b4-cf33a375ae5b
> which fails on LFS because vol_id is not in $PATH .  So maybe there is
> a  case  for putting  such  things  in /bin  rather  than  /lib ?
/sbin then, it's a system command.

> It 
> certainly suggests that other distros  do that, since the writer seems
> to assume  that these commands will  be in $PATH .   (I understand the
> reasons for not putting them in /usr .)

Well, like the articles says you can use blkid too. 

I look in my gentoo system and see that /sbin/vol_id is a symlink 
to /lib/udev/vol_id. Perhaps putting it in other directories than /lib/udev 
can break the udev if it expect find this files in /lib and have this 
hardcoded (I don't know if this is true, it's a assumption). 

I find vold_id calls on udev rules of gentoo systems too using the symlink in 

> (BTW, I'm not  trying to lay down the law here,  just raising an issue
> than confused me and wondering what it means.)
I understand.

> > ... personaly,  I put the iptables  modules there [not  in /usr] too
> > (my Firewall starts very early :-) )
> OK, I'm interested.  I consider myself fairly security-conscious but I
> can't  see the  need  to  start iptables  before  mounting local  file
> systems  like /usr  .   As long  as  your firewall  starts before  the
> network, what  could possibly go wrong?  (Famous  last words!)  Unless
> your /usr is networked?
My network system is in /sbin and I start the iptables scripts just after it. 
I do this because I create a distro based on Linux From Scratch to use in my 
clients and for default it has a base (INPU/OUTPUT) firewall rules. So, 
before any other things goes up for network services, I start it in the base 
boot. Like I use some very simples boot scripts I put it on early start aside 
udev, mounts and others.

In fact the FORWARD rules are load after, with network daemons and others in 
the case of the host be a gateway. 

> Regards,
> Jeremy Henty


Valter Douglas Lisbôa Jr.
Trenix - IT Solutions
"Nossas Idéias, suas Soluções!"
contato at trenix.com.br

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