mongodb启动不了：child process failed, exited with error number 48

梦里梦外; 2022-03-30 05:08 578阅读 0赞

**问题：**

启动mongodb的时候，发现起不来，报错：child process failed, exited with error number 48然后先去/var/log/mongo/mongod.log 查看启动的日志

**可能原因：**

应该是没有正常关闭mongodb引起的，比如直接 kill -9 <pid>导致

**解决方法：**

1.找到mongod.lock文件，并删除mongod.lock

2.以修复方式启动mongodb

/usr/bin/mongod -f /etc/mongod.conf --repair

3.然后接着在启动一次

/usr/bin/mongod -f /etc/mongod.conf --auth

4.查看进程是否运行

ps aux|grep mongo

**正确关闭mongodb的方法**

**warning：千万不能使用kill -9 <pid>,因为MongoDB使用mmap方式进行数据文件管理，也就是说写操作基本是在内存中进行，写操作会被每隔60秒(syncdelay设定)的flush到磁盘里。如果在这60秒内flush处于停止事情我们进行kill -9那么从上次flush之后的写入数据将会全部丢失。  
如果在flush操作进行时执行kill -9则会造成文件混乱，可能导致数据全丢了，启动时加了repair也无法恢复。**

**官方文档：****https://docs.mongodb.org/manual/tutorial/manage-mongodb-processes/**

## Stop mongod Processes ##

In a clean shutdown a [mongod][] completes all pending operations, flushes all data to data files, and closes all data files. Other shutdowns are *unclean* and can compromise the validity of the data files.

To ensure a clean shutdown, always shutdown [mongod][] instances using one of the following methods:

### Use shutdownServer() ###

Shut down the [mongod][] from the [mongo][] shell using the [db.shutdownServer()][db.shutdownServer] method as follows:

use admin
    db.shutdownServer()

Calling the same method from a [init script][] accomplishes the same result.

For systems with [authorization][] enabled, users may only issue [db.shutdownServer()][db.shutdownServer] when authenticated to the admin database or via the localhost interface on systems without authentication enabled.

### Use \--shutdown ###

From the Linux command line, shut down the [mongod][] using the *--shutdown* option in the following command:

mongod --shutdown

### Use CTRL-C ###

When running the [mongod][] instance in interactive mode (i.e. without *--fork*), issue Control-C to perform a clean shutdown.

### Use kill ###

From the Linux command line, shut down a specific [mongod][] instance using the following command:

kill <mongod process ID>

WARNING

Never use kill \-9 (i.e. SIGKILL) to terminate a mongod instance.

[mongod]: https://docs.mongodb.org/manual/reference/program/mongod/#bin.mongod
[mongo]: https://docs.mongodb.org/manual/reference/program/mongo/#bin.mongo
[db.shutdownServer]: https://docs.mongodb.org/manual/reference/method/db.shutdownServer/#db.shutdownServer
[init script]: https://docs.mongodb.org/manual/reference/glossary/#term-init-script
[authorization]: https://docs.mongodb.org/manual/reference/configuration-options/#security.authorization