mongodb 启动失败：ERROR: child process failed, exited with error number 100
ERROR: child process failed, exited with error number 100
原因：之前没有正常结束 解决：查看mongo.conf文件，dbpath=/data/mongodb/，进入目录，rm mongod.lock这个文件。
rm mongod.lock
重新启动：进入mongodb安装文件夹，bin/mongod -f /usr/local/mongodb/bin/mongo.conf即可
bin/mongod -f /usr/local/mongodb/bin/mongo.conf
