Do you know all Java networking properties?

Just in case you are in need of setting a proxy host or declaring proxy exceptions in your JVM I find this site very useful:
http://java.sun.com/j2se/1.5.0/docs/guide/net/properties.html
It lists all existing Java networking properties.

Ever wanted to know the exact name of your installed Linux distribution?

Type this command into shell and find out what Linux distro you are using:

cat /etc/issue

It gives you something like this:

Ubuntu 8.04.1 \n \l

If you don't know the kernel you are running with try this one:

uname -a

It gives you something like this:

Linux machinename 2.6.24-19-generic #1 SMP Wed Jun 4 16:35:01 UTC 2008 i686 GNU/Linux

Problems updating my Debian Distribution, or do you know MMAP?

I was recently trying to update my Debian (lenny/sid) distro and ran into some problems I never had so far:
When calling

apt-get update

I got the following error message:

E: Dynamic MMap ran out of room
E: Ein Fehler trat beim Bearbeiten von g++-4.2 auf (NewVersion1)
E: Problem with MergeList /var/lib/dpkg/status

After digging around I found a solution for my problem:
Increase the Cache Limit size of APT in /etc/apt/apt.conf like this:

APT::Cache-Limit 80000000;

Be careful not to set the size too high!