I'm using following small shell script to launch MongoDB:

#!/bin/sh
MONGO_DIR='/home/pawel/bin/mongo'
$MONGO_DIR/bin/mongod --bind_ip 127.0.0.1 --logpath $MONGO_DIR/log/mongo.log --fork --dbpath $MONGO_DIR/db/ --directoryperdb

When I'll launch this, MongoDB process is starting but main process is not closing, i.e. I've following in my console:

$ /home/pawel/bin/mongo/start_mongo.sh
about to fork child process, waiting until server is ready for connections.
forked process: 10044
all output going to: /home/pawel/bin/mongo/log/mongo.log

When checking processes list, I see 3 instances of MongoDB running:

$ ps ax | grep mongo
10041 pts/0 S+ 0:00 /bin/sh /home/pawel/bin/mongo/start_mongo.sh
10042 pts/0 S+ 0:00 /home/pawel/bin/mongo/bin/mongod --bind_ip 127.0.0.1 --logpath /home/pawel/bin/mongo/log/mongo.log --fork --dbpath /home/pawel/bin/mongo/db/ --directoryperdb
10043 ? Ss 0:00 /home/pawel/bin/mongo/bin/mongod --bind_ip 127.0.0.1 --logpath /home/pawel/bin/mongo/log/mongo.log --fork --dbpath /home/pawel/bin/mongo/db/ --directoryperdb
10044 ? Sl 0:02 /home/pawel/bin/mongo/bin/mongod --bind_ip 127.0.0.1 --logpath /home/pawel/bin/mongo/log/mongo.log --fork --dbpath /home/pawel/bin/mongo/db/ --directoryperdb

In log file I've only this:

Sun Jan 5 11:23:02.114 [initandlisten] MongoDB starting : pid=10044 port=27017 dbpath=/home/pawel/bin/mongo/db/ 64-bit host=metis
Sun Jan 5 11:23:02.114 [initandlisten] db version v2.4.8
Sun Jan 5 11:23:02.114 [initandlisten] git version: a350fc38922fbda2cec8d5dd842237b904eafc14
Sun Jan 5 11:23:02.114 [initandlisten] build info: Linux ip-10-2-29-40 2.6.21.7-2.ec2.v1.2.fc8xen #1 SMP Fri Nov 20 17:48:28 EST 2009 x86_64 BOOST_LIB_VERSION=1_49
Sun Jan 5 11:23:02.114 [initandlisten] allocator: tcmalloc
Sun Jan 5 11:23:02.114 [initandlisten] options:

Unknown macro: { bind_ip}

Sun Jan 5 11:23:02.322 [initandlisten] journal dir=/home/pawel/bin/mongo/db/journal
Sun Jan 5 11:23:02.340 [initandlisten] recover : no journal files present, no recovery needed
Sun Jan 5 11:23:03.332 [websvr] admin web console waiting for connections on port 28017
Sun Jan 5 11:23:03.333 [initandlisten] waiting for connections on port 27017

When I'll hit Ctrl+C in console, parent process is closing (PID=10042 from the list above) and rest of 2 are still running (PID: 10043, 10044) and I can use MongoDB.
When I'm trying to send SIGTERM to first process (PID=10043) nothing happens, and when I'll send SIGTERM to PID=10044, (with kill 10044 shell command) both processes are closing and I've following in log file:

Sun Jan 5 11:37:05.346 [signalProcessingThread] got signal 15 (Terminated), will terminate after current cmd ends
Sun Jan 5 11:37:05.346 [signalProcessingThread] now exiting
Sun Jan 5 11:37:05.346 dbexit:
Sun Jan 5 11:37:05.346 [signalProcessingThread] shutdown: going to close listening sockets...
Sun Jan 5 11:37:05.346 [signalProcessingThread] closing listening socket: 9
Sun Jan 5 11:37:05.346 [signalProcessingThread] closing listening socket: 10
Sun Jan 5 11:37:05.346 [signalProcessingThread] closing listening socket: 11
Sun Jan 5 11:37:05.346 [signalProcessingThread] removing socket file: /tmp/mongodb-27017.sock
Sun Jan 5 11:37:05.346 [signalProcessingThread] shutdown: going to flush diaglog...
Sun Jan 5 11:37:05.346 [signalProcessingThread] shutdown: going to close sockets...
Sun Jan 5 11:37:05.346 [signalProcessingThread] shutdown: waiting for fs preallocator...
Sun Jan 5 11:37:05.346 [signalProcessingThread] shutdown: lock for final commit...
Sun Jan 5 11:37:05.347 [signalProcessingThread] shutdown: final commit...
Sun Jan 5 11:37:05.449 [signalProcessingThread] shutdown: closing all files...
Sun Jan 5 11:37:05.450 [signalProcessingThread] closeAllFiles() finished
Sun Jan 5 11:37:05.450 [signalProcessingThread] journalCleanup...
Sun Jan 5 11:37:05.450 [signalProcessingThread] removeJournalFiles
Sun Jan 5 11:37:05.594 [signalProcessingThread] shutdown: removing fs lock...
Sun Jan 5 11:37:05.594 dbexit: really exiting now

And now when I'll start MongoDB server again, the same happens