Archive for the 'Tech' Category

Well, first off, thanks Lars Wirzenius (liw) for this really fine piece of software, it saved me from the mailman hell I was going to enter.

That being said, here’s the setup, with Postfix 2.0 and virtual domains on a Sarge system; the manpage of eoc is slightly outdated wrt to Postfix it seems, so I hope this will be helpful (with apologies to Planet readers for the length of this entry):

• Create an eoc or whatever user, who will receive the mails and hold the eoc configuration. I created a system user, with a disabled password and /bin/bash as its shell, member of the list group.
• su - eoc and create your mailing list, with something like
  
enemies-of-carlotta --name=testlist@lists.example.com --owner=foo@example.com --create

  Now, add yourself to the testlist:
  
enemies-of-carlotta --name=testlist@lists.example.com --subscribe your@email.address

  As eoc places its configuration data in ~/.enemies-of-carlotta, it’s important to run the enemies-of-carlotta command as the eoc user.
• Edit /etc/postfix/main.cf, and add the file /etc/postfix/virtual_eoc_aliases to the virtual_alias_map configuration item, e.g.
  
...
virtual_alias_maps = hash:/etc/postfix/virtual_aliases, pcre:/etc/postfix/virtual_eoc_aliases
...


  Now, create /etc/postfix/virtual_eoc_aliases:
  
#
# virtual aliases for EOC (mailing-lists)
#
 
/^(testlist|testlist-.*)@(lists.example.com)$/ eoc+lists.example.com_$1


  This way, a mail addressed to (testlist|testlist-.*)@lists.example.com will be redirected to eoc+lists.example.com_<whatgotmatched>.

  You’ll need the postfix-pcre package for this to work, and the recipient delimiter must be set to + (recipient_delimiter = + in /etc/postfix/main.cf). Restart postfix.

• Send a mail to your test list, it should end up in the mailbox of your eoc user. If it doesn’t, check the postfix logs and fix the problem ;-)
• Create the .forward file in the user’s homedir, here’s its content
  
"| procmail -p"

• Now, create the .procmailrc file for the eoc user. This is what I came up with:
  
PATH=$HOME/bin:/bin:/usr/bin
LOGFILE=$HOME/eoc-log
ARCHIVES=$HOME/archives
THISMONTH=`date "+%Y%m"`
 
# determine the full list name (list@domain)
:0
EOCLIST=| eoc-extract-list $EXTENSION
 
# set recipient to the full list name, ie list@domain
RECIPIENT=$EOCLIST
 
# feed the mail to EOC
:0
* ? enemies-of-carlotta --name=$EOCLIST --is-list
{
# send the mail to the list
:0 c
| enemies-of-carlotta --quiet --incoming
 
# archive it
UMASK=033
:0
$ARCHIVES/$EOCLIST/${THISMONTH}.mbox
}
 
# trap other mails ...
:0
trapped-mails


  The eoc-extract-list does nothing more than that, at the moment:
  
echo $1 | sed -e 's/\([^_]*\)[_]\(.*\)/\2@\1/'

  The trapped-mails mbox file will need to be emptied periodically; actually, I redirect those mails to another address, feel free to pass them on to Dave Null.
  As you can see, the mails get archived in an mbox by the procmail rule. I use mhonarc to generate a web archive from this mbox.

OK, here you are, your test mailing-list should now be functional. Send a mail, and see what happens.

To add a list, all you have to do is:

• Add the regexp into /etc/postfix/virtual_eoc_aliases
• Create the list in eoc

The procmailrc doesn’t need to be modified afterwards. It can probably be improved still, but I’m happy with it as it is now.

Now, if someone knows of a mailing-list archiver that doesn’t suck, I’d be glad to give it a try.

A couple of weeks ago, I needed to make a big PostScript file (4x3m, more on this later), and it seems like InkScape won’t let me use an arbitrary format. So I went ahead, googled for a PostScript tutorial, got the BlueBook as the first result and downloaded the reference manual for PostScript level 3 from Adobe.

I must say that PostScript is really a fun language to play with, and I had quite some fun doing something that would have been pretty boring otherwise. Enjoy the power of a complete programing language to automatise a couple of things while you’re at it.

I eventually had a look at the DSC and EPS specifications too, and ended up reading the PDF reference for PDF 1.6. I’m quite disappointed they scrapped the “PostScript is a complete programing language” part. I’m also quite disappointed by the “let’s use byte offsets in the xref table”, which is really painful to manage when writing a PDF file with a text editor, but I admit that it’s probably the best solution.

So, it was time for a cool hack using what I gathered about PS and PDF. Here it is, I added EPS and PDF as output formats for the screenshot in TiLP; the screenshot is written as a raw RGB (or black & white) inline image, compressed with zlib and encoded in ASCII85.

I wish I had learned all of this a year ago, when I had to debug a printing problem with CUPS. Now I can tell what the bug was; CUPS wasn’t honoring the DSC indicating the next page was to be printed on A3 paper with landscape orientation. Instead, the stupid thing added a DSC telling the page was to be printed on A4 paper. If this bug still exists, I’m going to send them a dead-tree copy of the DSC specs, so they can bang their heads against it :-P