I'm installing tomcat6 on ubuntu 9.10 and getting the following:

sudo apt-get install tomcat6

Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
jsvc libcommons-daemon-java
Suggested packages:
tomcat6-docs tomcat6-admin tomcat6-examples
The following NEW packages will be installed:
jsvc libcommons-daemon-java tomcat6
0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
Need to get 0B/88.8kB of archives.
After this operation, 766kB of additional disk space will be used.
Do you want to continue [Y/n]? y
Selecting previously deselected package libcommons-daemon-java.
(Reading database ... 179106 files and directories currently installed.)
Unpacking libcommons-daemon-java (from .../libcommons-daemon-java_1.0.2~svn20061127-9ubuntu2_all.deb) ...
Selecting previously deselected package jsvc.
Unpacking jsvc (from .../jsvc_1.0.2~svn20061127-9ubuntu2_i386.deb) ...
Selecting previously deselected package tomcat6.
Unpacking tomcat6 (from .../tomcat6_6.0.20-2ubuntu2.1_all.deb) ...
Processing triggers for doc-base ...
Processing 1 added doc-base file(s)...
Registering documents with scrollkeeper...
Processing triggers for man-db ...
Processing triggers for ureadahead ...
Setting up libcommons-daemon-java (1.0.2~svn20061127-9ubuntu2) ...

Setting up jsvc (1.0.2~svn20061127-9ubuntu2) ...
Setting up tomcat6 (6.0.20-2ubuntu2.1) ...
chgrp: cannot access `/etc/tomcat6/tomcat-users.xml': No such file or directory
dpkg: error processing tomcat6 (--configure):
subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
tomcat6
E: Sub-process /usr/bin/dpkg returned an error code (1)

Please help me to fix this issue.

chgrp: cannot access `/etc/tomcat6/tomcat-users.xml': No such file or directory is the relevant error.

Try purging tomcat6, apt-get update'ing, then installing.