secureCRT Chinese green portable version download address Extraction code: 3ury

first step

1. Enter the host name:
2. Enter username: root
3. Click OK

Second step

1. enter password

third step

Can see the following display to prove that it has been successful
Enter ls directly, nothing is displayed?
Then try typing first

cd /
ls

---

 
   The mongodb configuration file is /etc/mongod.conf  
   The directory where mongodb/data is configured is in /var/lib/mongodb

You will encounter the following problems when starting up:

 ERROR: listen(): bind() failed errno:98 Address already in use for socket: 0.0.0.0:27017

Encountered this problem, the port has been occupied and needs to be killed.
Solution:

---

If you use mongod to start, you encounter exception in initAndListen: 29 Data directory /data/db not found., terminating

This problem is encountered because mongodb thinks that /data/db is the default path, and we have no effect by starting in /etc/mongod.conf.
Start the database with the following statement

mongod -f /etc/mongod.conf

Reference solution:https://laike9m.com/blog/ubuntu-yun-xing-mongodb-de-zheng-que-zi-shi,64/

Use of mongodb

After mongodb starts

Mongo //Use this command to connect to the database
 Show dbs //View which libraries are available

Note: mongodb uses security mechanisms. You must first create a userAdminAnyDatabase user in the admin repository and another user through the userAdminAnyDatabase user.

  use admin
> switched to db admin
  db.createUser( {
    user: "usa",
    pwd: "usa",
    roles: [ { role: "userAdminAnyDatabase", db: "admin" } ]
  })

• Next create the user of the database we use

    Use mongodb / / switch to mongodb library we use
> switched to db mongodb  
  db.createUser( {
    user: "username",
    pwd: "password",
    roles: [ { role: "readWrite", db: "mongodb" } ]
  })
     // Currently only read and write permissions are given

• When we connect the data again

  use mongodb
  db.auth('username','password')
 > 1 //Return 1 for successful access 0 is failed

• Here we can operate the database on the command line.

/ / Use this command to view all tables first 
show collections;

• Common operation

 / / Delete the table
 db.config.drop()
 db.users.drop()
 db.worklist.drop()

   / / Query formatting
 db.worklist.find().pretty();