How to remove old lock file terminating mongodb

dileep@dileep-VirtualBox:~$ sudo mongod --dbpath /var/lib/mongodb/
Sat Dec 28 01:36:55.801
Sat Dec 28 01:36:55.803 warning: 32-bit servers don't have journaling enabled by default. Please use --journal if you want durability.
Sat Dec 28 01:36:55.804
Sat Dec 28 01:36:55.933 [initandlisten] MongoDB starting : pid=2656 port=27017 dbpath=/var/lib/mongodb/ 32-bit host=dileep-VirtualBox
Sat Dec 28 01:36:55.936 [initandlisten]
Sat Dec 28 01:36:55.937 [initandlisten] ** NOTE: This is a 32 bit MongoDB binary.
Sat Dec 28 01:36:55.937 [initandlisten] **       32 bit builds are limited to less than 2GB of data (or less with --journal).
Sat Dec 28 01:36:55.938 [initandlisten] **       Note that journaling defaults to off for 32 bit and is currently off.
Sat Dec 28 01:36:55.939 [initandlisten] **       See http://dochub.mongodb.org/core/32bit
Sat Dec 28 01:36:55.939 [initandlisten]
Sat Dec 28 01:36:55.940 [initandlisten] db version v2.4.8
Sat Dec 28 01:36:55.941 [initandlisten] git version: a350fc38922fbda2cec8d5dd842237b904eafc14
Sat Dec 28 01:36:55.941 [initandlisten] build info: Linux bs-linux32.10gen.cc 2.6.21.7-2.fc8xen #1 SMP Fri Feb 15 12:39:36 EST 2008 i686 BOOST_LIB_VERSION=1_49
Sat Dec 28 01:36:55.942 [initandlisten] allocator: system
Sat Dec 28 01:36:55.942 [initandlisten] options: { dbpath: "/var/lib/mongodb/" }
**************
Unclean shutdown detected.
Please visit http://dochub.mongodb.org/core/repair for recovery instructions.
*************
Sat Dec 28 01:36:55.951 [initandlisten] exception in initAndListen: 12596 old lock file, terminating
Sat Dec 28 01:36:55.952 dbexit:
Sat Dec 28 01:36:55.952 [initandlisten] shutdown: going to close listening sockets...
Sat Dec 28 01:36:55.953 [initandlisten] shutdown: going to flush diaglog...
Sat Dec 28 01:36:55.955 [initandlisten] shutdown: going to close sockets...
Sat Dec 28 01:36:55.956 [initandlisten] shutdown: waiting for fs preallocator...
Sat Dec 28 01:36:55.957 [initandlisten] shutdown: closing all files...
Sat Dec 28 01:36:55.959 [initandlisten] closeAllFiles() finished
Sat Dec 28 01:36:55.959 dbexit: really exiting now

To remove the Error we only do ,

dileep@dileep-VirtualBox:/$ cd var/lib/mongodb
dileep@dileep-VirtualBox:/var/lib/mongodb$ sudo rm mongod.lock
dileep@dileep-VirtualBox:/var/lib/mongodb$ ls
local.0  local.ns  _tmp

Then have to put the mongod --repair comand for repairing the mongodb. or else try to do the

 sudo mongod --dbpath /var/lib/mongodb/      command in the terminal.

Then the mongodb will work again.