CentOS 6 in a chroot

When fiddling with CentOS 6.x in a chroot:

  • If your host architecture is x86_64 but your chroot architecture is i686 then you’ll find that yum update will try to install lots of x86_64 packages, and then fail. That’s because the arch command still returns “x86_64”. You’ll want to use setarch:
    # arch
    # setarch i386 /bin/bash
    # arch
  • You’ll need to make sure you have a useful /proc as otherwise yum won’t be able to work out how much free disk space there is and will refuse to proceed. Bind mounting is probably easiest:
    $ sudo mount --bind /proc /srv/your/chroot/proc
  • You might find that things you install aren’t labelled correctly for SELinux. If this is a virtual machine then you can force it to relabel on boot:
    $ sudo touch /srv/your/chroot/.autorelabel

    fixfiles may also work, but I haven’t tried that.

Thanks to Alex for the setarch tip which I had not come across before.

Adding watermarks to a PDF with Perl’s PDF::API2

For ages I’ve been trying to work out how to programmatically add a watermark to an existing PDF using the Perl PDF::API2 module.

In case it’s useful for anyone else, here goes:

use warnings;
use strict;

use PDF::API2;

my $ifile = "/some/file.pdf";
my $ofile = "/some/newfile.pdf";
my $pdf   = PDF::API2->open($ifile);
my $fnt   = $pdf->ttfont('verdana.ttf', -encode => 'utf8');
# Only on the front page
my $page  = $pdf->openpage(1);
my $text  = $page->text;


# Create two extended graphic states; one for transparent content
# and one for normal content
my $eg_trans = $pdf->egstate();
my $eg_norm  = $pdf->egstate();


# Go transparent
# Black edges
# With light green fill
# Text render mode: fill text first then put the edges on top
# Diagonal transparent text
$text->textlabel(55, 235, $fnt, 56, "i'm in ur pdf", -rotate => 30);
# Back to non-transparent to do other stuff

# …

# Save

I think there may be better ways of doing this within Perl now, but I already had some code using PDF::API2.

My email marketing adventure with British Telecom

The saga so far ^

I have a phone line from BT. I only use it for ADSL (which I get from Zen Internet). I gave my email address to BT because they offered to tell me useful things about my account via email. I now wish I had never done this.

I use extension addresses to identify what the email addresses are being used for. This is not a new idea and I didn’t invent it. For those who don’t know what an extension address is, it’s an email address like andy+foo@example.com. It ends up at the same place as andy@example.com. The point is that if I receive an email to andy+foo@example.com then I know that it’s either from whoever I gave that address to, or it’s from someone they gave/lost my address to. It’s handy for working out who’s sold their database to spammers, or had it stolen.

I used to prefer using “+” in the extension address just because it looks nicer to me than other popular alternatives like “-“. Unfortunately, some web developers are idiots and don’t believe that “+” is valid in an email address, so they try to help by refusing to accept the address. For that reason my email servers accept both “+” and “-” and I used to use “-” when “+” wasn’t accepted.

After I started doing that, I began to experience an even more annoying failure: web sites that accepted “+” in my email address when I signed up, but later got redeveloped by idiots who think that “+” is no longer valid. That means that I can no longer log in to those sites, and predictably customer service is not trained to deal with situations like that.

It seems that BT is an example of such a company, and I am having unbelievable difficulty finding anyone there that can understand this.

When I signed up with BT, the email address I gave them had a “+” in it. They accepted it at the time.

March 2011 ^

I start to receive marketing emails from BT for extra BT services, as well as BT group companies such as Dabs and Plusnet.

29th March 2011 ^

I receive another marketing email from BT, decide I don’t want to receive them any more, and follow the unsubscribe link. The unsubscribe page at http://bt.custhelp.com/app/contact/c/769,978 tells me that the email address (which BT is emailing me on) is invalid.

I contact BTCare on Twitter to ask them how to opt out and to opt me out on my behalf. Also sent a request via BT’s site for someone to call me back about it.

Am called back by a polite BT chap who totally failed to understand the problem, told me I was opted out (funny, I never opted in…) and advised that I sign up to a no commercial email scheme.

18th April 2011 ^

Receive more marketing email from BT. Ask BTCare on Twitter why that is. Am told that it can take a month to take effect.

18th May 2011 ^

Receive more marketing email from BT. Ask BTCare on Twitter why that is.

29th May 2011 ^

BTCare tells me on twitter that they opted out the wrong address last time. Apologises and says it may take a further month.

25th July 2011 ^

BT sends me a marketing email on behalf of Plusnet.

2nd August 2011 ^

I (somewhat exasperatedly) ask BTCare if, since they can’t opt me out of the emails, we can come to a more formal arrangement for my proofreading services of £50 per future email.

BTCare replies that “We can’t opt you out of emails for other companies” and that “no compensation is available sorry.”

I point out that Plusnet is a BT company, that the emails are sent by BT on an email address given only to BT, and contain a BT unsubscribe link which does not work.

3rd August 2011 ^

BTCare asks if the email was from BT, and advises the use of a US-based commercial email opt-out site.

4th August 2011 ^

BTCare tells me that their unsubscribe link works now and that I should try it again. I try it again. It fails the same way. I tell BTCare.

5th August 2011 ^

BTCare tells me that I need to contact Plusnet directly: “the link may be BT related but its seperate to us and we have no control over them

PlusNet (on twitter and identica) disagrees with BTCare and says BT sends those emails and operates the unsubscribe facility. They give me an email address at Plusnet to forward the marketing to anyway.

I have forwarded the email there and have so far got nothing back except an out of office email bounce. Oh well, it’s not really their problem anyway.

What to do now? ^

I would quite like to send a snail mail letter to BT to complain about this cluelessness. Does anyone know the best postal address and entity within BT for that to be directed to? If nothing else perhaps I can start sending the £50 a time invoices there?

I’d also quite like to not be a BT customer after this. I’m not too aware of my choices on that front though. My DSL is currently through Zen Internet, who I’m fairly happy with. I’d like a bit faster but don’t want to become a Sky or Virgin Media customer.

I’m told I can get Zen to “take over the copper”. What does this mean? Would it cause me difficulty in switching to another ISP in future?

Finally I have a feeling that there’s some DPA consequences for failing to opt me out of marketing in 4 months of asking, and then saying that I can’t get them to opt me out of marketing from companies they have given my email address to. Worth dropping a line to ICO?

Just hit delete / block all email from BT ^

Yeah it’s not that annoying but hopefully you can agree that this run-around is ridiculous. While I remain a BT customer I would prefer not to bitbucket all email from them as they do sometimes send stuff related to the operation of my account.

On extension addresses ^

It’s a shame, but I now consider “+” as unusable in an extension address because of idiot web developers who turn sites that used to accept these completely valid addresses into sites that reject them.

Just use “-” instead. It doesn’t look as pretty but at least not even the most ill-informed developer can think that “-” is invalid. If your email address already contains “-” (perhaps because your name does?), shit, sucks to be you.