Reproduce steps:

mongodb-linux-x86_64-1.5.7/bin/mongod --shardsvr --dbpath data/ --replSet set1

This is deliberately incorrect.

Actual output:

all output going to: mongodb.log
forked process: 1084
[root@domU-12-31-39-06-29-52 ~]#

• • NOTE: This is a development version (1.5.7) of MongoDB.
  • Not recommended for production.

Expected output:

Sun Aug 1 04:05:45 MongoDB starting : pid=1091 port=27018 dbpath=data/ 64-bit

• • NOTE: This is a development version (1.5.7) of MongoDB.
  • Not recommended for production.

Sun Aug 1 04:05:45 db version v1.5.7, pdfile version 4.5
Sun Aug 1 04:05:45 git version: 5b667e49b1c88f201cdd3912b3d1d1c1098a25b4
Sun Aug 1 04:05:45 sys info: Linux domU-12-31-39-06-79-A1 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_41
Sun Aug 1 04:05:45 [initandlisten] exception in initAndListen std::exception: bad --replSet config string format is: <setname>/<seedhost1>,<seedhost2>[,...], terminating
Sun Aug 1 04:05:45 dbexit:

Sun Aug 1 04:05:45 [initandlisten] shutdown: going to close listening sockets...
Sun Aug 1 04:05:45 [initandlisten] shutdown: going to flush oplog...
Sun Aug 1 04:05:45 [initandlisten] shutdown: going to close sockets...
Sun Aug 1 04:05:45 [initandlisten] shutdown: waiting for fs preallocator...
Sun Aug 1 04:05:45 [initandlisten] shutdown: closing all files...
Sun Aug 1 04:05:45 closeAllFiles() finished

Sun Aug 1 04:05:45 [initandlisten] shutdown: removing fs lock...
Sun Aug 1 04:05:45 dbexit: really exiting now

Problem

The log file is not created because of the error, and since the process is forked before the error occurs, the process fails silently.