apt-get command showing error

Increase the limit. Open a terminal and run:

gksudo gedit /etc/apt/apt.conf

Add to the bottom:

APT::Cache-Limit "16777216";

Then run:

sudo apt-get clean; sudo apt-get update

Post back any errors.

Your sources list seems not correct - there are error messages about dapper and lucid shown above.

Please issue the following commands and copy/paste the output:

uname -a
lsb_release -a
cat /etc/apt/sources.list
ls -la /etc/apt/sources.list.d

@ manfred hampl hey thanx 4 d help...following r d output
uname -a
Linux ubuntu 2.6.32-28-generic #55-Ubuntu SMP Mon Jan 10 21:21:01 UTC 2011 i686 GNU/Linux
neha@ubuntu:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 10.04.2 LTS
Release: 10.04
Codename: lucid
neha@ubuntu:~$ cat /etc/apt/sources.list
# deb cdrom:[Ubuntu 10.04.2 LTS _Lucid Lynx_ - Release i386 (20110211.1)]/ lucid main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

deb http://us.archive.ubuntu.com/ubuntu/ lucid main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ lucid main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://us.archive.ubuntu.com/ubuntu/ lucid-updates main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ lucid-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://us.archive.ubuntu.com/ubuntu/ lucid universe
deb-src http://us.archive.ubuntu.com/ubuntu/ lucid universe
deb http://us.archive.ubuntu.com/ubuntu/ lucid-updates universe
deb-src http://us.archive.ubuntu.com/ubuntu/ lucid-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://us.archive.ubuntu.com/ubuntu/ lucid multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ lucid multiverse
deb http://us.archive.ubuntu.com/ubuntu/ lucid-updates multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ lucid-updates multiverse

## Uncomment the following two lines to add software from the 'backports'
## repository.
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
# deb http://us.archive.ubuntu.com/ubuntu/ lucid-backports main restricted universe multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ lucid-backports main restricted universe multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu lucid partner
# deb-src http://archive.canonical.com/ubuntu lucid partner

deb http://security.ubuntu.com/ubuntu lucid-security main restricted
deb-src http://security.ubuntu.com/ubuntu lucid-security main restricted
deb http://security.ubuntu.com/ubuntu lucid-security universe
deb-src http://security.ubuntu.com/ubuntu lucid-security universe
deb http://security.ubuntu.com/ubuntu lucid-security multiverse
deb-src http://security.ubuntu.com/ubuntu lucid-security multiverse
deb http://us.archive.ubuntu.com/ubuntu/ hardy multiverse
# deb http://qgis.org/debian lucid main
deb http://archive.ubuntu.com/ubuntu/ edgy multiverse universe main restricted
deb-src http://archive.ubuntu.com/ubuntu/ edgy multiverse universe main restricted
deb http://security.ubuntu.com/ubuntu/ edgy-security universe main multiverse restricted
deb-src http://security.ubuntu.com/ubuntu/ edgy-security universe main multiverse restricted
deb http://archive.ubuntu.com/ubuntu/ edgy-updates universe main multiverse restricted
deb http://ppa.launchpad.net/ubuntugis/ppa/ubuntu lucid main deb-src http://ppa.launchpad.net/ubuntugis/ppa/ubuntu lucid main
deb http://ppa.launchpad.net/ubuntugis/ppa/ubuntu lucid main deb-src http://ppa.launchpad.net/ubuntugis/ppa/ubuntu lucid main
deb http://ubuntu.mirror.cambrium.nl/ubuntu/ maverick main
deb http://ubuntu.mirror.cambrium.nl/ubuntu/ maverick main
deb http://security.ubuntu.com/ubuntu lucid-security main universe
deb http://ubuntu.mirror.cambrium.nl/ubuntu/ dapper main universe
deb http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu lucid main deb-src http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu lucid main
deb http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu lucid main deb-src http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu lucid main
deb http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu lucid main
deb http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu lucid main
deb http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu lucid main
deb http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu lucid main
deb http://ppa.launchpad.net/ubuntugis/ubuntugis-unstable/ubuntu lucid main
neha@ubuntu:~$ ls -la /etc/apt/sources.list.d
total 16
drwxr-xr-x 2 root root 4096 2011-06-22 10:53 .
drwxr-xr-x 6 root root 4096 2011-06-28 01:50 ..
-rw-r--r-- 1 root root 76 2011-06-28 00:50 ubuntugis-ubuntugis-unstable-lucid.list
-rw-r--r-- 1 root root 76 2011-06-28 00:50 ubuntugis-ubuntugis-unstable-lucid.list.save

@wojox hey thanx 4 ur help
bt aftr running gksudo gedit /etc/apt/apt.conf
i m getting the prompt returned and nothing else.....!! wat 2 do..??

hey can any1 tel...my synaptic package manager is not running...it opens...shows error..and again shuts down...
ERROR
E: Dynamic MMap ran out of room. Please increase the size of APT::Cache-Limit. Current value: 25165824. (man 5 apt.conf)
E: Error occurred while processing xlhtml (NewFileDesc2)
E: Problem with MergeList /var/lib/apt/lists/ubuntu.mirror.cambrium.nl_ubuntu_dists_dapper_universe_binary-i386_Packages
E: The package lists or status file could not be parsed or opened.
E: _cache->open() failed, please report.

W: Duplicate sources.list entry http://security.ubuntu.com/ubuntu/ lucid-security/universe Packages (/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_lucid-security_universe_binary-i386_Packages)
W: Duplicate sources.list entry http://ppa.launchpad.net/ubuntugis/ppa/ubuntu/ lucid/main Packages (/var/lib/apt/lists/ppa.launchpad.net_ubuntugis_ppa_ubuntu_dists_lucid_main_binary-i386_Packages)
W: Duplicate sources.list entry http://ppa.launchpad.net/ubuntugis/ppa/ubuntu/ lucid/main Packages (/var/lib/apt/lists/ppa.launchpad.net_ubuntugis_ppa_ubuntu_dists_lucid_main_binary-i386_Packages)
W: Duplicate sources.list entry http://ppa.launchpad.net/ubuntugis/ppa/ubuntu/ lucid/main Packages (/var/lib/apt/lists/ppa.launchpad.net_ubuntugis_ppa_ubuntu_dists_lucid_main_binary-i386_Packages)
W: Duplicate sources.list entry http://ubuntu.mirror.cambrium.nl/ubuntu/ maverick/main Packages (/var/lib/apt/lists/ubuntu.mirror.cambrium.nl_ubuntu_dists_maverick_main_binary-i386_Packages)
W: Unable to munmap

WHATSOEVR COMMAND I GIVE..IT SHOWS THE FOLLOWING ERROR...SOMETHING HAS GONE WRONG..PLEASEE HELP
COMMAND : sudo apt-get install postgresql postgresql-client postgresql-contrib pgadmin3
ERROR:
Reading package lists... Error!
W: Duplicate sources.list entry http://security.ubuntu.com/ubuntu/ lucid-security/universe Packages (/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_lucid-security_universe_binary-i386_Packages)
W: Duplicate sources.list entry http://ppa.launchpad.net/ubuntugis/ppa/ubuntu/ lucid/main Packages (/var/lib/apt/lists/ppa.launchpad.net_ubuntugis_ppa_ubuntu_dists_lucid_main_binary-i386_Packages)
W: Duplicate sources.list entry http://ppa.launchpad.net/ubuntugis/ppa/ubuntu/ lucid/main Packages (/var/lib/apt/lists/ppa.launchpad.net_ubuntugis_ppa_ubuntu_dists_lucid_main_binary-i386_Packages)
W: Duplicate sources.list entry http://ppa.launchpad.net/ubuntugis/ppa/ubuntu/ lucid/main Packages (/var/lib/apt/lists/ppa.launchpad.net_ubuntugis_ppa_ubuntu_dists_lucid_main_binary-i386_Packages)
W: Duplicate sources.list entry http://ubuntu.mirror.cambrium.nl/ubuntu/ maverick/main Packages (/var/lib/apt/lists/ubuntu.mirror.cambrium.nl_ubuntu_dists_maverick_main_binary-i386_Packages)
E: Dynamic MMap ran out of room. Please increase the size of APT::Cache-Limit. Current value: 25165824. (man 5 apt.conf)
E: Error occurred while processing xlhtml (NewFileDesc2)
E: Problem with MergeList /var/lib/apt/lists/ubuntu.mirror.cambrium.nl_ubuntu_dists_dapper_universe_binary-i386_Packages
W: Unable to munmap
E: The package lists or status file could not be parsed or opened.
neha@ubuntu:~$

Please be patient, you cannot expect immediate answers. Most of the supporters helping in such question and answer threads are doing that voluntarily in their free time without getting paid for that, and they usually have also to do something else for their living.

The contents of your sources.list show an unsound mix of different distributions.
lsb_release -a shows that you are on a lucid system, so all references to edgy, dapper, hardy, maverick are counterproductive and should be removed.

Please open a terminal and issue the following command

gksudo gedit /etc/apt/sources.list

This will open a small window and request for your password, and after entering the password will open an editor window with your sources.list loaded.

Please perform the folowing changes on your sources.list:

Go down line by line until you find the following line:

deb http://us.archive.ubuntu.com/ubuntu/ hardy multiverse

delete that line
delete the line that follows (containing debian)
delete the following five lines (containing edgy)

modify the next line (containing ubuntugis/ppa/ubuntu lucid) by breaking the line in two lines between 'main' and 'deb-src' thus making two lines out out that, the first one starting with deb and the second one starting with deb-src
do the same to the line that follows

delete the next two lines (containing maverick)
delete the next line (containing lucid, because this is a duplicate)
delete the next two lines (containing dapper)
delete all lines that follow (containing ubuntugis/ubuntugis-unstable)

If you have done that each line in the whole file should
either start with a '#' sign (then it is a comment line)
or start with deb
or start with deb-src
or be completely empty.

Save the file and close the editor.

Try the commands

cat /etc/apt/sources.list
cat /etc/apt/sources.list.d/ubuntugis-ubuntugis-unstable-lucid.list
sudo apt-get update

and post the output as done before.

If you have problems with performing any action please post the details as exact as possible.

i am sorry...i was patient..its just that i was providing more and more info abt errors so that it becomes easy 4 u 2 detect.....nywazz thanxx 4 taking tym 4 my queriess....ur solution helpedd me alot...it is solved now...synaptic manager is well now..thanx..thanx alt.....!!!!