LinuxQuestions.org - Notes on Linux

I leave notes here that I find particularly worth remembering myself.

Howto fix long boot delay with "Starting MTA:" (Common Issue)

Posted 06-10-2010 at 12:20 PM by bittner (Notes on Linux)

Tags debian, exim4, mta

A common issue when setting up servers in a lab is that the Mail Transfer Agent (MTA) delays the boot process waiting for a very long timeout. In the forums on the web this reads as ...

"boot process slow when 'Starting MTA' offline"
"Can I get rid of MTA?"
"Starting MTA delay"
"I see a line saying Starting MTA: It takes ages until Debian comes."

The issue is typically related to an unsuccessful reverse DNS lookup that the Mail Transfer Agent...

bittner

LQ Newbie

Posted in Uncategorized

Views 5557 Comments 0 bittner is offline

Howto automate interactive Debian package installations (debconf preseeding)

Posted 06-08-2010 at 07:44 AM by bittner (Notes on Linux)
Updated 06-08-2010 at 06:59 PM by bittner

Tags administration, debian, package

Fully automatic installations make sense when you need to install a vast number of machines. For Debian (but not limited to it) there is the FAI project that helps you with those kind of undertakings.

When FAI uses Debian packages (i.e. .deb files) for installation the automatic installation process gets into trouble when such a package asks for manual configuration interactively. Really, this is not specific to FAI: The Debian installer (the installation wizard guiding you through...

bittner

LQ Newbie

Posted in Uncategorized

Views 2870 Comments 0 bittner is offline

Shortest command to calculate the sum of a column of output

Posted 06-02-2010 at 06:27 AM by bittner (Notes on Linux)

Tags bash, debian, packaging, script

I had to calculate the Installed-Size for a .deb control file recently. Here is the solution I came up with:

Code:

dpkg-deb -c mypackage.deb | sed -e 's/.*root\s*//' -e 's/\s*2010-.*$//' | xargs | tr ' ' + | bc

What it does? The code tries to construct a calculation string and feeds it to the command line calculator bc as follows:

use dpkg-deb to get the file size information out of the Debian package
sed away all characters before and after the

...

bittner

LQ Newbie

Posted in Uncategorized

Views 2040 Comments 2 bittner is offline

Howto build your own Debian repository

Posted 06-01-2010 at 05:04 AM by bittner (Notes on Linux)
Updated 06-07-2010 at 07:08 AM by bittner (added reference (background reading))

Tags administration, debian, packages

If you write software for Linux and you write them for Debian systems (Debian, Ubuntu, and others) you may want to provide your software as .deb installation packages. And one day eventually you will want to set up a repository so others can download and install your software without fuzz.

If you look at a Debian mirror (e.g. http://ftp.debian.org/debian/) you will find out one day that packages and meta information is split up into two main directories on the root level:

dists

...

bittner

LQ Newbie

Posted in Uncategorized

Views 7005 Comments 1 bittner is offline

Unix runlevel scripts: Finally the first character makes sense!

Posted 05-29-2010 at 04:12 PM by bittner (Notes on Linux)

Tags administration, script

You probably know Unix runlevel scripts. They start with an S or a K, and they are typically located at /etc/rcX.d/ with X being the runlevel (0-6) the script is supposed to run at. For example:

Code:

~$ ls -l /etc/rc5.d/*cups
lrwxrwxrwx 1 root root 14 2009-12-31 16:35 /etc/rc5.d/S50cups -> ../init.d/cups

To be precise those S- and K- files are typically symbolic links to scripts that reside in /etc/init.d/, and from my experience I felt they work as follows:

Any symlink

...

bittner

LQ Newbie

Posted in Uncategorized

Views 1459 Comments 0 bittner is offline

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