I am researching now the simple "use" command for the mongo command. Please help me.
I just want save the my query in a file, but before that i need to connect to a certain database. For that i tried to find a "use" command like in sql, but could not find anything.
I just want to execute something like
mongo ....--use [db] --eval 'db.find' > save.query
In your question, you didn't specify what platform you're using, are you using Linux? Windows? Anyway, if you want to use the command line for mongo db then I would recommend to use the mongodb shell. Download the mongodb shell https://www.mongodb.com/try/download/shell and select what platform you're using.
https://www.mongodb.com/docs/mongodb-shell/run-commands/#mongosh-usage
That sais you have use <database> command
I just got it. You can just add the database name:
mongo [dbname] --host etc.
and it worked.
This is the easiest way in linux:
Option 1 ( command line params )
echo "db.exampleollection.find({}).forEach(function(d){printjson(d)})" | mongo --quiet exampledatabase --host "examplehost" --port "examplePort" --authenticationDatabase=admin -u "exampleuser" -p "examplepassword" > output.json
Explained:
Send the command you need to execute via echo to the mongo shell and redirect the output to the result file.
Add the option --quiet to suppress the shell printed info
You can provide the database directly in as comman line argument.
Option 2 : same way but URI format:
echo "show collections" | mongo "mongodb://user:pass#host:port/database?authSource=admin" --quiet
I'm not a Bash/Linux person, but I've been asked to just come up with the lines needed to run to authenticate against a database and then drop it. Here is what I have so far and I'm not sure if it's correct:
mongo mydatabase –port –username <username> –password <password> –authenticationDatabase admin –eval “ printjson(db.dropDatabase())”
If it's possible to use one line to delete any database whose name starts with "cpt_" then that would be absolutely ideal.
Thanks!
You can use -
Get all the names
Loop and check if the name starts with cpt_
drop the database
db.getMongo().getDBNames().forEach(function(dbName){ if (dbName.startsWith('cpt_')) printjson(db.getSiblingDB(dbName).dropDatabase())
Full
mongo –port –username <username> –password <password> –authenticationDatabase admin --eval "db.getMongo().getDBNames().forEach(function(dbName){ if (dbName.startsWith('cpt_')) printjson(db.getSiblingDB(dbName).dropDatabase()) })"
I am attempting to create a single archive file for each database in Mongo. Is there a way to create a batch file that will automatically create an archive (.archive) for each database without me manually entering the database name?
The snipet provided
mongodump --host hostename --port portname --username username --password password --authenticationDatabase admin --db databasename --archive=name.arvhive
I would like to create the archive file without having to specify the database name. Is this possible? If not, is there a way to dump all of the databases and create a single gzip for each database?
Any assistance would be greatly appreciated.
Thanks!
In order to get the DB names in the mongo instance we need to use the mongo show dbs command.
Since we want to be able to use this inside a script, we want to run that command and exit the mongo cli, to do that we can pass a js file to mongo, like so:
$ echo "show dbs" > showDbs.js
$ mongo < showDbs.js
Which will result in something like
MongoDB shell version v3.4.22
connecting to: mongodb://127.0.0.1:27017
MongoDB server version: 3.4.22
admin 0.000GB
animals 0.366GB
people 0.012GB
local 0.000GB
bye
Since we need to parse the result, we can use the --quiet option to reduce the output. We can also skip creating the showDbs.js file so that we don't have to clean it up later.
Now we have:
$ mongo --quiet <<< "show dbs"
admin 0.000GB
animals 0.366GB
people 0.012GB
local 0.000GB
All that's left to do is to parse the result to remove the db sizes, and then run the mongodump command for each of the databases (I'm leaving that command as it is)
To remove the size information for each database we'll use sed and match for a whitespace, since whitespaces are not allowed in database names
$ sed 's/\s\+.\+//' <<< "$dbs"
Putting it all together we get the following script
#!/bin/bash
dbs=$(mongo --quiet <<< "show dbs")
dbs=$(sed 's/\s\+.\+//' <<< "$dbs")
for db in $dbs; do
mongodump --host hostname --port portname --username username --password password --authenticationDatabase admin --db $db --archive=$db.archive
done
We are using MongoDB user based authentication, and I want to quickly run a command to check whether a user has already been created in the database, in order that puppet won't repeatedly attempt to create the user.
Here is how we check if the replica set has initialised:
/usr/bin/mongo --host ${members[0]} --quiet --eval 'rs.status().ok' | grep -q 1
Is a similar trick possible with authentication? I've checked the documentation here http://www.mongodb.org/display/DOCS/dbshell+%28mongo%29+Reference and I can't see a way of doing it?
Yes, on a given DB, you can use db.system.users.find({user:'login'}).count() which will return 0 if the user does not exist.
It feels that this method has been deprecated, I needed the following command to work:
db.getUsers({filter: {'user': 'login'}})
Today I just tried -u and -p options for mongo command and it worked for me:
mongo --port 27037 --quiet -u superuser -p pwd
--eval "db.system.users.find({user:'user3'}).count()" admin
Note the last "admin" arg - it is the name of database, to which you are authenticating.
To check if a user username exists:
db.runCommand({ usersInfo: { user: "username", db: "admin" } }).users.length == 1
This will return true if the user exists, and false otherwise. (If the user was created in another database, replace admin with the name of the database.)
You can also use findOne
db.system.users.findOne({user:'login'})
it will null if no user
it will return user if found
What's the easiest way to do this from my bash prompt?
Like this:
mongo <dbname> --eval "db.dropDatabase()"
More info on scripting the shell from the command line here: https://docs.mongodb.com/manual/tutorial/write-scripts-for-the-mongo-shell/#scripting
Edit:
In Mongo 6.0 mongo was removed and replaced with mongosh which has to be installed separately. More info here: https://www.mongodb.com/docs/mongodb-shell/#mongodb-binary-bin.mongosh
The best way to do it is from the mongodb console:
> use mydb;
> db.dropDatabase();
Alternatively, you can stop mongod and delete the data files from your data directory, then restart.
Hint: you can also move the data files to a subfolder, and delete them if you're sure you no longer need them.
I found this easy to remember:
mongo //to start the mongodb shell
show dbs //to list existing databases
use <dbname> //the <dbname> is the database you'd like to drop
db //should show <dbname> just to be sure I'm working with the right database
db.dropDatabase() //will delete the database & return { "dropped" : "<dbname>", "ok" : 1 }
You don't need heredocs or eval, mongo itself can act as an interpreter.
#!/usr/bin/env mongo
var db = new Mongo().getDB("someDatabase");
db.dropDatabase();
Make the file executable and run it.
Start MongoDB
Command for Database drop is :
1. first select the database which you want to delete
use < database name >
2. Then use this..
db.dropDatabase()
You could also use a "heredoc":
mongo localhost/db <<EOF
db.dropDatabase()
EOF
Results in output like:
mongo localhost/db <<EOF
db.dropDatabase()
EOF
MongoDB shell version: 2.2.2
connecting to: localhost/db
{ "dropped" : "db", "ok" : 1 }
bye
I like to use heredocs for things like this, in case you want more complex sequence of commands.
Here are some use full delete operations for mongodb using mongo shell
To delete particular document in collections: db.mycollection.remove( {name:"stack"} )
To delete all documents in collections: db.mycollection.remove()
To delete collection : db.mycollection.drop()
to delete database :
first go to that database by use mydb command and then
db.dropDatabase()
directly from command prompt or blash : mongo mydb --eval "db.dropDatabase()
Other way:
echo "db.dropDatabase()" | mongo <database name>
Execute in a terminal:
mongo // To go to shell
show databases // To show all existing databases.
use <DATA_BASE> // To switch to the wanted database.
db.dropDatabase() // To remove the current database.
Open another terminal window and execute the following commands,
mongodb
use mydb
db.dropDatabase()
Output of that operation shall look like the following
MAC:FOLDER USER$ mongodb
> show databases
local 0.78125GB
mydb 0.23012GB
test 0.23012GB
> use mydb
switched to db mydb
>db.dropDatabase()
{ "dropped" : "mydb", "ok" : 1 }
>
Please note that mydb is still in use, hence inserting any input at that time will initialize the database again.
Open a terminal and type:
mongo
The below command should show the listed databases:
show dbs
/* the <dbname> is the database you'd like to drop */
use <dbname>
/* the below command will delete the database */
db.dropDatabase()
The below should be the output in the terminal:
{
"dropped": "<dbname>",
"ok": 1
}
Using Javascript, you can easily create a drop_bad.js script to drop your database:
create drop_bad.js:
use bad;
db.dropDatabase();
Than run 1 command in terminal to exectue the script using mongo shell:
mongo < drop_bad.js
Eventhough there are several methods, The best way (most efficient and easiest) is using db.dropDatabase()
In you command prompt, First connect to mongodb using following command:
mongo -h [host-name]:[port:number] -d [dbname] -u [username] -p [password]
you will be accessing db with <dbname>.
Run the following command to drop the whole database:
db.dropDatabase()
one liner remote remove all collections from mongo database
note must use --host, (-h is help for mongo command), and -d is not an option, select the db and command after password.
mongo --host <mongo_host>:<mongo_port> -u <db_user> -p <db_pass> <your_db> --eval "db.dropDatabase()"
Surprised that we haven't seen this variation come up. This minimizes extra args on the command line and explicitly shows the DB being switched to FOO and then dropped:
$ mongo --host "mongodb://machine:port" --eval 'db.getSiblingDB("FOO").dropDatabase();'
LogIn into your mongoDB command line:
And type the below commands.
use "YOUR_DATABASE_NAME";
db.dropDatabase();
Drop a MongoDB database using python:
import argparse
import pymongo
if __name__ == "__main__":
"""
Drop a Database.
"""
parser = argparse.ArgumentParser()
parser.add_argument("--host", default='mongodb://localhost:27017',
help="mongodb URI [default: %(default)s]")
parser.add_argument("--database", default=None,
help="database name: %(default)s]")
args = parser.parse_args()
client = pymongo.MongoClient(host=args.host)
if args.database in client.list_database_names():
client.drop_database(args.database)
print(f"Dropped: '{args.database}'")
else:
print(f"Database '{args.database}' does not exist")
In order to be really sure that you drop the correct database use
mongo <connection properties> --eval "db.getSiblingDB('dbname').dropDatabase()"
See Authentication failure while trying to save to mongodb to understand the concerns.
You can first switch to your database which you want to delete. Then you can delete the same by using the command dropDatabase().
Code :
>use dbName
>db.dropdataBase()
The result will be :
{ "dropped" : "dbName", "ok" : 1 }
If you want to delete a specific collection in a database, then switch to the database and enter the following command.
Code:
>use dbName
db.collection.drop()
The result will be :
true
If you want a better understanding of MongoDB shell commands it's
better to follow the documentation always.
Link to the documentation :
https://www.mongodb.com/docs/manual/reference/method/#std-label-js-administrative-methods
db will show the current Database name
type: db.dropDatabase();
1- select the database to drop by using 'use' keyword.
2- then type db.dropDatabase();
use following command from mongo shell to drop db
use <database name>;
db.dropDatabase();