Re: Common problems with Ubuntu

[Dotan Cohen]

On 12 May 2010 01:17, Micha Feigin  wrote:
> Lets start with the problem that Microsoft encourages all users to be set as
> administrators by default. It's almost impossible to be a regular user usually
> and just switch momentary to administrator for small administration tasks ...
>

I thought that the last two versions of Windows corrected that.


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Re: Common problems with Ubuntu

[Dotan Cohen]

On 12 May 2010 08:45, geoffrey mendelson  wrote:
> UBUNTU does have a process where you can sync the packages installed on one
> computer with another. You do it by listing the status of all packages to a
> file, input the file to the package manager on the other computer and then
> tell it to install anything it now thinks should be installed and isn't. I
> think that is done via dpkg, so any debian based system will do the same
> thing.
>

I've never heard of that! Going through the manpage, it looks like you
might be referring to "get-selections". Is that it? If not, can you
give some more details? Thanks!


Back on topic, to answer the OP:
In contrast to some other distros, Ubuntu does not come with
development tools. You have to install them yourself. Once they are
installed, Ubuntu is just like any other Linux distro in regards to
development. In fact, you will notice that Ubuntu often has very
up-to-date packages available, and they are very easy to install with
tools such as build-dep.



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Client recovery of NFS mount

[Tom Rosenfeld]

Hi Guys,

Is there a way in RHEL 5 for NFS clients to recover automatically after a
server reboot?
Every time my server goes down, even for just a few minutes the clients get
stuck with STALE nfshandles and the only way for me to recover is to umount
and then mount again.
Isn't there some mount option that will allow the clients to retry until the
server replies again?

Thanks,
-tom
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Re: Common problems with Ubuntu

[Dotan Cohen]

On 12 May 2010 10:16, geoffrey mendelson  wrote:
>> I've never heard of that! Going through the manpage, it looks like you
>> might be referring to "get-selections". Is that it? If not, can you
>> give some more details? Thanks!
>>
>
>
> http://ubuntuforums.org/showthread.php?t=261366
>

Nice, thanks!


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Re: Common problems with Ubuntu

[Tzafrir Cohen]

On Wed, May 12, 2010 at 08:45:39AM +0300, geoffrey mendelson wrote:
>
> On May 12, 2010, at 8:22 AM, Gilboa Davara wrote:
>>
>> Though, I doubt that the OP will care if he's installing Linux from a
>> single LiveCD or from an installation DVD. (I would assume that if  
>> he's
>> talking about multiple machines, the DVD version will be far less
>> bandwidth hog)
>
>
>
> Actually it does not matter. Just about all of the modern distros  
> dowload their add ons or updates to a staging directory. 

The Debian installer (and IIRC aalso the Ubuntu one) use the package
manager to install all but the (tiny) base system.

> Some of them  
> have cleanup set to run by cron, some never clean up, waiting for you to 
> do it manually.

Network installer + apt cacher of some sort is even more
bandwidth-efficient. For instance, it will also cache security updates.

This also allows you to easily define the set of packages you want.

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Re: Client recovery of NFS mount

[Ehud Karni]

On Wed, 12 May 2010 10:28:13 Tom Rosenfeld wrote:
>
> Is there a way in RHEL 5 for NFS clients to recover automatically after a
> server reboot?

There is the "hard" (and "intr" that can go with it) option for NFS mounts:
  hard  If an NFS file operation has a major timeout then report  "server  not
responding"  on  the console and continue retrying indefinitely.  This
is the default.

  intr  If an NFS file operation has a major timeout and it is  hard  mounted,
then  allow  signals  to  interupt  the file operation and cause it to
return EINTR to the calling program.  The default is to not allow file
operations to be interrupted.

Note that "hard" is the default, but the option "soft" (or "nohard") cancels it.

I use "hard,intr" and it solve the problem you describe in most case but
not all (I did not find the reasons for the different behavior).

> Every time my server goes down, even for just a few minutes the clients get
> stuck with STALE nfshandles and the only way for me to recover is to umount
> and then mount again.

Try my suggestion above.

Ehud.


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Re: Common problems with Ubuntu

[Shlomi Fish]

On Wednesday 12 May 2010 08:09:30 Ori Idan wrote:
> 2010/5/12 Elazar Leibovich 
> 
> > I think you have to make a distinction between older MS software (such as
> > XP) and newer ones (such as 7). For example you defenitely don't run as
> > administrator in Windows 7, and you've got a built-in sudo like system.
> > I, like some people who replied, had bad experience managing Windows
> > machines, and it was usually viruses. However in recent versions I
> > noticed that even at the hands of the inexperienced users, and without
> > any virus scanner, the system stays relatively clean.
> > 
> > The point about Windows complexity and background compatability is true
> > and taken. It is against security, and maybe it tips the balance against
> > MS and Windows related products security-wise.
> > 
> > The other remark which I highly disagree is that there's no need to
> > convince me. I'm discussing here in order to be convinced, and I'm
> > usually glad when someone enlightens me.
> > 
> > On Tue, May 11, 2010 at 3:17 PM, Micha Feigin wrote:
> >> On Tue, 11 May 2010 04:08:39 -0700
> 
> >> Elazar Leibovich  wrote:
> I do not understand how a discussion about Ubuntu as a development station
> became into discussion about windows security and management.

Discussions divert to other topics on the Internet just like in face-to-face 
discussions. That's life, and I don't find it a bad fact about us humans. I 
personally found both the discussion about Ubuntu (which didn't start from its 
suitability as a development station, but has diverted into that sub-topic 
too), and the discussion about Windows security and Microsoft's security 
practices, interesting and welcome here. (Given that most of previous 
discussions died pretty quickly and tended to be less interesting.)

If you wish to understand how the discussion diverted, you can look at the 
mailing list's online archives:

http://www.iglu.org.il/mailing-lists/linux-il.html

Regards,

Shlomi Fish

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Re: Common problems with Ubuntu

[Shlomi Fish]

On Wednesday 12 May 2010 08:53:02 Baruch Even wrote:
> On Tue, May 11, 2010 at 7:43 PM, Shlomi Fish  wrote:
> > On Tuesday 11 May 2010 16:04:29 Amos Shapira wrote:
> > > On 11 May 2010 22:01, geoffrey mendelson 
> > 
> > wrote:
> > > > On May 11, 2010, at 2:52 PM, Dotan Cohen wrote:
> > > >> Ubuntu packages three Javas, but only the Sun Java has any worth.
> > > >> The other two only serve to mess up Sun Java installs. Stay away
> > > >> from them.
> > > > 
> > > > Ouch, that brings back another UBUNTU problem. It does not install
> > > > Java (are most programs) in /usr/bin. It installs them in /usr/bin
> > > > under another name, or eleswhere. Then it links
> > > > /etc/alternatives/ to them. Then it links /usr/bin/ to
> > > > /etc/alternatives/.
> > > 
> > > That's actually part of the inheritance from Debian. Debian tends to
> > > have a long history behind most of their decisions so this system
> > > makes sense there. I'm not sure how different is Ubuntu from it
> > > though.
> > 
> > Last time I checked (Debian 3.1 or so), Debian did not take the
> > /etc/alternatives system to its natural conclusion though. I noticed that
> > when
> > I wanted to install postfix on what was then eskimo.iglu.org.il, I had to
> > uninstall qmail (which I wanted to get rid of eventually), because the
> > /usr/sbin/sendmail file conflicted between the two packages. Later on,
> > when I
> > worked on Fedora, I was able to install Postfix as well as sendmail (the
> > Fedora default) because I could play with the symlinks in
> > /etc/alternatives and other places. It's possible it was fixed in Debian
> > since then.
> 
> qmail was not packaged in Debian since it was non-free, not sure about its
> status nowadays. If you install something yourself or from an unofficial
> package you can not blame Debian for its failures.
> 

First of all, I should note that qmail was installed using the official 
installation procedure for Debian (there wasn't a publicly available binary 
package because qmail's author forbade distributing binary packages in the 
source code's distribution terms). Much more recently, the qmail source was 
made public domain (which Debian should not have a problem with, since they 
packaged my Freecell Solver, which also used to be public domain, although 
possibly under more explicit terms of what I mean by "Public Domain" than 
qmail's), but in the meanwhile qmail has accumulated many known bugs, and 
didn't keep up with recent changes in the E-mail landscape. There's also 
netqmail naturally, but it is not supported by the qmail author. 
http://qmail.org/netqmail/ - this seems out-of-date.

Anyway, I believe that the problem in Debian would have been exhibited even if 
I wanted to install exim in addition to postfix, or sendmail in addition to 
postfix etc. because they all supplied a /usr/sbin/sendmail file which was not 
a symlink.

Regards,

Shlomi Fish

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Re: Common problems with Ubuntu

[Diego Iastrubni]

On יום רביעי 12 מאי 2010 21:40:30 Shlomi Fish wrote:
> Anyway, I believe that the problem in Debian would have been exhibited even
> if I wanted to install exim in addition to postfix, or sendmail in
> addition to postfix etc. because they all supplied a /usr/sbin/sendmail
> file which was not a symlink.

RTFM - "man update-alternatives". It has been explained in this thread. Please 
stop the FUD.

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Re: Client recovery of NFS mount

[Oron Peled]

On Wednesday, 12 בMay 2010 13:55:51 Ehud Karni wrote:
> On Wed, 12 May 2010 10:28:13 Tom Rosenfeld wrote:
> > Is there a way in RHEL 5 for NFS clients to recover automatically after a
> > server reboot?
> 
> There is the "hard" (and "intr" that can go with it) option for NFS mounts:
> ...

Beside the very valid and good advice Ehud just gave, let me add another one.
Move to NFS4 (both server and clients of course). I have done it some 2 years
ago and it pays big time in reliability (also performance, but that's less
noticable in my (low-volume) case).

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Re: Common problems with Ubuntu

[Shlomi Fish]

On Wednesday 12 May 2010 23:27:41 Diego Iastrubni wrote:
> On יום רביעי 12 מאי 2010 21:40:30 Shlomi Fish wrote:
> > Anyway, I believe that the problem in Debian would have been exhibited
> > even if I wanted to install exim in addition to postfix, or sendmail in
> > addition to postfix etc. because they all supplied a /usr/sbin/sendmail
> > file which was not a symlink.
> 
> RTFM - "man update-alternatives". It has been explained in this thread.
> Please stop the FUD.

Just to protect myself against accusations of spreading "FUD": I wasn't 
referring to what Debian has presently (which may be very different from what 
existed back then) - I was referring to its past condition. I don't know what 
the present condition is in regards to having multiple E-mail servers 
installed at the same time, but back when I tried "apt-get install postfix" 
asked me if I wanted to remove qmail. This may no longer be the case, and I'm 
sorry if I hadn't made myself clear enough.

Regards,

Shlomi Fish

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Re: Common problems with Ubuntu

[geoffrey mendelson]

On May 13, 2010, at 1:37 AM, Shlomi Fish wrote:




Just to protect myself against accusations of spreading "FUD": I  
wasn't
referring to what Debian has presently (which may be very different  
from what
existed back then) - I was referring to its past condition. I don't  
know what

the present condition is in regards to having multiple E-mail servers
installed at the same time, but back when I tried "apt-get install  
postfix"
asked me if I wanted to remove qmail. This may no longer be the  
case, and I'm

sorry if I hadn't made myself clear enough.



Wait a minute. Having more than one MTA installed would be a disaster.  
Any sane packager would make postfix, qmail, sendmail, exim, etc all  
mutually exclusive. If you put enough effort you could install them  
all at the same times, but you would have to have different spool  
directories, (mail queues),
different binary directories, different control file directories and  
if any of them were accepting incoming connections, have them listen  
on different ports.


Since only one of them could use the standard locations and ports, it  
would be an undertaking of massive proportions that no one could  
anticipate in a package. You would have to install and configure each  
of them from the source files.


Sendmail is not very difficult to do it if you know what you are  
doing, I've only installed the others that I have used via package  
managers, so I can't say. Of course then there is the sendmail.cf  
file, something so complicated there is an m4 macro package to make it  
from a higher level config file.


Geoff.
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situation. i.e possessing less facts or information than can be found  
in the Wikipedia.








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Re: Common problems with Ubuntu

[Oleg Goldshmidt]

geoffrey mendelson  writes:

> Wait a minute. Having more than one MTA installed would be a
> disaster.  Any sane packager would make postfix, qmail, sendmail,
> exim, etc all mutually exclusive.

"Installed at the same time" and "operational at the same time" are
not the same thing. This is one of the things that "alternatives"
helps to achieve - you switch between MTAs with a single command
(assuming they are all properly configured, etc.). I suppose you also
need to stop and start the corresponding services.

I feel like I'm defending "alternatives". I do not intend to. IMHO, it
is a rather horrible kludge, but it is not the problem... ;-)

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Re: Common problems with Ubuntu

[geoffrey mendelson]

On May 13, 2010, at 9:16 AM, Oleg Goldshmidt wrote:


"Installed at the same time" and "operational at the same time" are
not the same thing. This is one of the things that "alternatives"
helps to achieve - you switch between MTAs with a single command
(assuming they are all properly configured, etc.). I suppose you also
need to stop and start the corresponding services.



Not with MTA's. They have various files with the same names, files in  
the same locations, etc. that are incompatible. While everyone likes  
to put them in /etc/mail (with some linked by the same file name in / 
etc), you would need to have an /etc/mail/sendmail, /etc/mail/qmail, / 
etc/mail/postfix, and so on tree, a /var/mail (or /var/spool/mail)  
sendmail or postfix or whatever tree and, and a whole bunch of  
executables switched with alternatives, among them sendmail,  
newaliases, and so on.


You would also have to switch startup files, and parameter files and  
so on.


That's why an MTA package is set up as if it were the only one in the  
house. It's just too complicated to maintain.


Something like Java or GCC is simple beacuse it was designed with  
multiple versions being installed with one single front end module. So  
you can have cc, gcc, gcc-3, and gcc-4 executables all pointing to  
different executables which when they were compiled used a specific  
object and library tree, while the non release specific stuff (such as  
standard includes, kernerl includes, etc) are in the places you expect  
them, and they are compatible across all the releases.


There are also some specific problems if you want both alternatives  
active at the same time if the alternatives are packaged not to be  
that way. For example, mpg123 and mpg321. Both install a binary with a  
different name and the last alternative installed links /usr/bin/ 
mpg123 and /usr/bin/mpg321 to its binary. Fine for the average dumb  
user, but once you find out they are not really compatible and need  
both, you have to junk the alternative system and make sure that those  
packages are never updated by the system.


I guess if you were willing to persue the old "it's a bug, not a  
feature" debate with the developers, you could get mpg321 to be a 100%  
replacement for mpg123, but then all the people who expect mpg321 to  
act the way it does would be upset.


It comes down to the point that you have to decide if you want to let  
them (whomever "they" are) maintain your system for you, or do it  
yourself and how far away from reality as they see it you want to  
stray. For example, when I found that sendmail would not do what I  
needed without being manually compiled and installed, but the UBUNTU  
postfix would, although it took a lot of effort, I switched to postfix.


It was stressfull, but unless the packagers truely go "off the deep  
end" as I see it, I just have to install my config files, which use a  
lot of different values for options than theirs. I can just use their  
packages and if they get updated automaticly, the package manager is  
smart enough not to replace my config files.


Geoff.

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New word I coined 12/13/09, "Sub-Wikipedia" adj, describing knowledge  
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situation. i.e possessing less facts or information than can be found  
in the Wikipedia.








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