Mongodb启动child process failed, exited with error number 1

linux重启之后mongodb启动报错

```
about to fork child process, waiting until server is ready for connections.
forked process: 15246
ERROR: child process failed, exited with error number 1
To see additional information in this output, start without the "--fork" option.

```    这个原因是由于MongoDB的pid文件被linux重启清理掉了，需要修改/etc/mongo.conf文件下pid文件目录    `pidFilePath: /xxxxx/mongodb/mongod.pid`修改到一个固定的位置，例如`/mongodb/mongod.pid`    下面是具体的步骤：    1.创建空的MongoDB pid文件    ```    cd /    mkdir mongodb    cd mongodb    vi mongod.pid #保存空文件    ```    2.修改MongoDB配置文件    ```    [root@localhost ~]# whereis mongod    mongod: /usr/bin/mongod /etc/mongod.conf /etc/mongod.conf2 /usr/share/man/man1/mongod.1.gz    vi /etc/mongod.conf #修改pidFilePath为上面保存的文件 pidFilePath=/mongodb/mongod.pid    ```    3.重新启动MongoDB    ```    [root@localhost mongodb]# vi /etc/mongod.conf    [root@localhost mongodb]# /usr/bin/mongod -f /etc/mongod.conf    about to fork child process, waiting until server is ready for connections.    forked process: 15479    child process started successfully, parent exiting    ```