April 2007 - main

Etch...
by mephi 08 Apr '07

08 Apr '07

I don't know how many Debian users there are on this list, but for those of you that are, it's looking like Etch is finally released. I'm apt-get-ing now, I wonder how much this is gonna break my server. www.debian.org Matt

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Redundant web hosting
by Mark Rogers 08 Apr '07

08 Apr '07

Any reason why the following won't work? It sounds too "easy"... Server A is the primary DNS for a domain, and hosts its website, its database, and its email (SMTP in, dropped to POP3 mailboxes via spamassassin). All relevant records are in the DNS: www., pop3., etc, and point to Server A. Server B is the secondary DNS for a domain, but all the records (www./pop3./etc) point to Server B (not A). Server B has an exact copy of the website, the database (synchronised through MySQL replication), and drops any email it receives through its own spamassassin into its local POP3 mailboxes. Server A also uses fetchmail to collect mail from Server B and drop it into its local POP3 boxes, in case any arrives there. TTL on DNS records on both servers is set to a short period (say 15 mins). In normal use, the domain resolves to server A and server B just acts as a redundant backup. If/when server A fails, its DNS vanishes and so clients request from the DNS on server B, which directs them to the website and database on server B and drops email into its local POP3 mailboxes. (The end user, when checking their email, will likewise get Server B when they query pop3.theirdomain and start collecting email from Server B.) When server A recovers, things go back to normal, with any remaining mail in the POP3 mailboxes on Server B pulled over by fetchmail. Server A and B will be in entirely different locations (maybe not even on the same continent!) The only obvious problem which comes to mind is that writes to the database on Server B will get the databases out of sync, therefore I'd make remove write access to the databases from the website and modify the website code to handle that. In case anyone ends up at server B when server A is up and running, it could be told to connect remotely to the database on server A unless it can't, falling back to database B. In this scenario session handling would be messed up unless the session info is stored in the database and sync'd across. NB: From experience a lot of spam follows the lower priority MX in case it bypasses the spam checker, which would put a lot of the spam load onto the redundant server, hopefully allowing legitimate email through more quickly. -- Mark Rogers // More Solutions Ltd (Peterborough Office) // 0845 45 89 555 Registered in England (0456 0902) at 13 Clarke Rd, Milton Keynes, MK1 1LG

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CSS question, probably very naive.
by Chris G 05 Apr '07

05 Apr '07

I'm sure there's something fundamentally silly wrong with this but I can't see what it is at the moment. Here's a snippet of a CSS file:- .header { border-top: thick solid #cccccc; border-bottom: thin solid #cccccc; color: #0E0E0E; background: #EEEEEE; height: 8em; } h1.header, h2.header, h3.header, h4.header, h5.header, h6.header { padding: 0px; background: #EEEEEE; color: #003366; font-weight:normal; line-height:140%; } .crumbs {color: blue; background: white;} a.crumbs {color: red; background: white;} a.crumbs:visited {color: blue; background: white; text-decoration: none} Now the .header bit is doing what I expect for the part of my HTML that has a <div class="header"> ..... </div> around it, I get a nice pale grey background. But none of the h1/h2/h3/h4 'inside' the header seem to work. They still get a default white background. Similarly the .crumbs is working (I tried changing the background to check) but none of the a.crumbs are working. What am I doing wrong? Surely something obvious and silly but I can't see it. I even ran a CSS checker on it and it checks out perfectly, just doesn't actually do anything! -- Chris Green

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Re: Webmin/Usermin & proxies
by Matthew 05 Apr '07

05 Apr '07

Progress! With a <Proxy> block to Allow from all, I get 500 rather than 403 ;-) It looks like an Apache issue still, although I can't be sure. I saw a neat trick somewhere about trapping errors in your proxy (so that you can serve a different page if your backend application server is down); maybe I can find the instructions again and use that to work out where the fault is. Curiously, I have a set of other virtual servers that proxy heavy requests to another instance of Apache and I don't recall having declared a <Proxy> with Allow for them. They use mod_rewrite instead of ProxyPass, but I get the same results either way when passing requests to Usermin. I'll try some more tweaking; thanks for the help. >> I believe you need to add something like >> >> <Proxy *> >> Order deny,allow >> Allow from all >> </Proxy> >> >> To allow access to the proxy. > > I've just been reliably informed (by Brett on IRC) that <Proxy *> is > not a good idea and that you should bind it to a particular ip:port > > So.. > > <Proxy ip:port> > Order deny,allow > Allow from all > </Proxy>

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Use of () in 'test' (or [ ])
by Chris G 05 Apr '07

05 Apr '07

I want to group some logic in a test in a bash script. I.e. I am trying to write something like:- if [ this -a (that -o theOther) ] but bash always complains about 'syntax error'. I have reduced the code to the trivial:- home$ if [ ( true ) ]; then but still get the syntax error. According to the man page for test the format is:- ( EXPRESSION ) EXPRESSION is true I *think* that is trying to tell me that I can use () to group parts of what is inside the []. However, as I said, it refuses to work as I expected. I have tried all combinations of spaces etc. either side of the () but it still just gives a syntax error. Is this just a case where the () are punctuation in the man page rather than real () to use in the expression? Or am I doing something obvious wrong? (probably!). I know I *could* rely on precedence in the tests to get the result I want but it's much easier to write and to understand using () for grouping the logic. -- Chris Green

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Linux 'split' OK; Windows 'join' ???
by ted.harding＠nessie.mcc.ac.uk 04 Apr '07

04 Apr '07

Hi Folks, A bit one foot in each camp this time. I have a large file to transfer from a Linux machine to a Win98 machine, and for practical reasons only able to use floppies. On Linux, split -C 1m nicely produces 1MB size chunks that fit on floppies and can then be read into the win98 machine. Done. So far so good. But -- what's the way to paste the bits together again on Windows? On Linux there's a choice of ways! But Windows?? Thanks -------------------------------------------------------------------- E-Mail: (Ted Harding) <ted.harding(a)nessie.mcc.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 04-Apr-07 Time: 01:11:40 ------------------------------ XFMail ------------------------------

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bt home hub - how to setup ubuntu to recognise modem
by elc＠freeola.net 04 Apr '07

04 Apr '07

> > Currently I am connected via usb, in due course I'm contemplating > buying a usb wireless dongle for this (my main pc) and also one for my > other pc also running windows. > > As I said, I'm an utter newbie to linux; - what is this gui-wireless > setup stuff? > > Thanks > Eric > > James Taylor wrote: >> Can you please provide more information. Are you using the hub >> wirelessly or is it on an eithernet connection or a usb connection? >> >> If its wireless, does your linux recognise the computers wireless >> card [is the wirless carrd usb? can you see other usb devices?] >> >> What do your default gui-wireless setup things tell you? >> >> Thanks >> JT >> >> ----- Original Message ----- From: <elc(a)freeola.net> >> To: "ALUG" <main(a)lists.alug.org.uk> >> Sent: Saturday, March 31, 2007 11:12 PM >> Subject: [ALUG] bt home hub - how to setup ubuntu to recognise modem >> >> >>> Help please. >>> I have a British Telecom broadband wireless bt home hub, - it works >>> well with windows, but I am dual booting with Ubuntu/Kubuntu and >>> neither is recognising this modem, and thus can't get online. >>> Can anyone tell me in very simple words how to do this - I am an >>> absolute newbie to linux. >>> Many thanks. >>> Eric >>> >>> _______________________________________________ >>> main(a)lists.alug.org.uk >>> http://www.alug.org.uk/ >>> http://lists.alug.org.uk/mailman/listinfo/main >>> Unsubscribe? See message headers or the web site above! >>> >> >> >> >> _______________________________________________ >> main(a)lists.alug.org.uk >> http://www.alug.org.uk/ >> http://lists.alug.org.uk/mailman/listinfo/main >> Unsubscribe? See message headers or the web site above! >> >> >

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Webmin/Usermin & proxies
by Matthew 04 Apr '07

04 Apr '07

This may be a bit of a long shot but is anyone familiar with Webmin or Usermin, and has anyone tried serving either from behind a proxy? I'd like to offer minimal Usermin to mail users and the like, but I'd like to proxy it through Apache to keep it in the same namespace (and on the same port) as the rest of my HTTPS applications. The most likely culprits for an Apache config issue are the proxy statements: ProxyPass / https://localhost:20000/ ProxyPassReverse / https://localhost:20000/ Usermin works fine as a direct request on port 20000, but the proxy returns 403: Forbidden. The Apache logs show the 403, but I think it was originated by Usermin and I can't find anything useful in its logs (it's not even producing one of the log files). Turning off Usermin's SSL doesn't make any difference, nor does using IP or FQDN instead of 'localhost' in the proxy directives. Usermin should be accepting connections from any IP, so I think it dislikes something about the proxying. I barely understand what mod_proxy is up to at the best of times. Anyone got any suggestions? Anything else I could look at? Thanks, Matthew

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Re: [ALUG] Linux 'split' OK; Windows 'join' ???
by ted.harding＠nessie.mcc.ac.uk 04 Apr '07

04 Apr '07

On 04-Apr-07 09:48:41, Mark Reid wrote: > Hi > > In MSDOS mode you can join them with the following command - copy /b > file1 + file2 + file3 + file4 + file5 file./XXX/ > > /b is the switch for binary. /a is for ascii > > Syntax at http://www.computerhope.com/copyhlp.htm > > > Another way is to create a spanning archive with Winzip under Wine and > then use Winzip to reconstitute it in Windows > > Regards > > Mark And thanks for that URL or, more generally, http://www.computerhope.com That looks like a good place to poke around in when out of my depth in foreign territory! Best wishes, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <ted.harding(a)nessie.mcc.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 04-Apr-07 Time: 12:24:42 ------------------------------ XFMail ------------------------------

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How to put newlines or returns in a shell variable *and* check they're there?
by Chris G 03 Apr '07

03 Apr '07

I want to set a variable in a shell (bash) script with a newline as one of the characters. First question, how do you do it? Second question, how do you prove it's there once you've done it? I *think* there are several fairly obvious ways of doing it, e.g. things like:- export fred="abcde ghijk" However the problem is that using 'echo' to see what you have done is totally useless as echo does so many clever things under the cover that you don't get to see what's actually in the variable at all. If you do the above and then say "echo $fred" you just get:- abcde ghijk Harrumph! *Surely* there's some way of saying "show me what's really in this variable/string" (a bit like 'od' but for variables). -- Chris Green

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