Ubuntu 14.04 installation of MongoDB 3.x

  mongodb, question

See the official installation tutorial

https://docs.mongodb.org/manual/tutorial/install-mongodb-on-ubuntu/

After mongo is executed

root@iZkZ:~# mongo
 Failed global initialization: BadValue Invalid or no user locale set.
 Please ensure LANG and/or LC_* environment variables are set correctly.

Linux had better use its own package manager to install the software, instead of downloading the source code for compilation and installation, it is easy to make mistakes.
Apt-get and yum/dnf are generally error-free.