sudo systemctl start mongod

Install MongoDB on Ubuntu
- Ensuring the server is up to date:
$ sudo apt update
$ sudo apt upgrade -y
$ sudo apt dist-upgrade -y
- Install Required Packages:
$ sudo apt install gnupg
$ echo "deb http://security.ubuntu.com/ubuntu impish-security main" | sudo tee /etc/apt/sources.list.d/impish-security.list
sudo apt update
sudo apt install libssl1.1
- Install MongoDB
$ wget -qO - https://www.mongodb.org/static/pgp/server-6.0.asc | sudo apt-key add -
$ echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu focal/mongodb-org/6.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-6.0.list
$ sudo apt update
$ sudo apt install -y mongodb-org
Once installed, check the version of MongoDB:
$ mongod -version
Once the service has been installed, start and enabling MongoDB Service:
$ sudo systemctl start mongod
$ sudo systemctl status mongod
Our MongoDB service is up and running, then enable it to start
on boot using:
$ sudo systemctl enable mongod 

wget -qO - https://www.mongodb.org/static/pgp/server-5.0.asc | sudo apt-key add -
echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu focal/mongodb-org/5.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-5.0.list
sudo apt-get update
sudo apt-get install -y mongodb-org

# https://www.mongodb.com/docs/manual/tutorial/install-mongodb-on-ubuntu/
sudo apt-get install gnupg
wget -qO - https://www.mongodb.org/static/pgp/server-6.0.asc | sudo apt-key add -
# for Ubuntu 20.04
echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu focal/mongodb-org/6.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-6.0.list
sudo apt-get update
sudo apt-get install -y mongodb-org
# if you get "mongodb-org-mongos : Depends: libssl1.1 (>= 1.1.1) but 1.1.0l-1~deb9u6 is to be installed" error
# https://stackoverflow.com/questions/50375979/getting-error-while-installing-mongodb-in-linux
wget http://archive.ubuntu.com/ubuntu/pool/main/o/openssl/libssl1.1_1.1.1-1ubuntu2.1\~18.04.20_amd64.deb
sudo dpkg -i libssl1.1_1.1.1-1ubuntu2.1~18.04.20_amd64.deb
sudo apt-get install -y mongodb-org

sudo mongod
# or
sudo mongod --fork --logpath /var/log/mongod.log # start in background
# or
sudo mkdir -p /data/db
sudo mongod --port 27017 --dbpath /data/db --fork --logpath /var/log/mongod.log

follow the steps from the below link
https://docs.mongodb.com/manual/tutorial/install-mongodb-on-ubuntu/

mongosh for connecting to terminal

# Update the package list
sudo apt update
# Install MongoDB
sudo apt install mongodb
# Start MongoDB service
sudo systemctl start mongodb
# Enable MongoDB service to start on system boot
sudo systemctl enable mongodb
# Verify MongoDB installation and service status
sudo systemctl status mongodb