What is JShell?

Small overview of fupcoming first official Java REPL
31 August 2017   1033

JShell is Java’s first official REPL (READ-EVAL-PRINT-LOOP) tool. It is part of JDK 9 is going to be released in September 2017.

JShell REPL creates a simple programming environment in the command line that can:

  • read user's input
  • evaluate it
  • print the result
  • repeat the cycle

It works similar to Python interpreter or other JVM languages that have a REPL like Scala, Kotlin and Groovy.

You can write Java language expressions and statements in the JShell REPL, and they will be evaluated on their own without having to wrap them in classes or methods.

Let's take a look how to start with JShell.

As mentioned above, JShell is a part of upcoming Java 9. But eraly access is already available. 

When JDK 9 is installed, type jshell in your terminal to start a JShell session -

$ jshell
|  Welcome to JShell -- Version 9
|  For an introduction type: /help intro


An interactive JShell session will be started and JShell will greet you with a welcome message.

Learn more with this tutorial

Canonical to Represent Minimal Ubuntu

New version of Ubuntu is created for servers, isolated containers based on Docker and cloud systems
12 July 2018   105

Ubuntu team presented a simplified version of the base image - Minimal Ubuntu. It is designed for servers, isolated containers based on Docker and cloud systems. The release features high performance, minimal load time and automation of applications in the cloud.

The small footprint of Minimal Ubuntu, when deployed with fast VM provisioning from GCE, helps deliver drastically improved boot times, making them a great choice for developers looking to build their applications on Google Cloud Platform.

Paul Nash

Group Product Manager, Google Cloud

The authors of the project emphasize the size of the distribution kit, which "weighs" 157 MB, and also supports the main cloud systems like Amazon EC2, Google Compute Engine (GCE), LXD and KVM / OpenStack, each of which has its own optimized version of the package. In addition, the OS-based image for operating with containers based on the Docker platform, compatible with the Kubernetes.

Minimal Ubuntu is designed for automated execution, so it includes only a minimal set of tools. The distribution can be upgraded to a set of Ubuntu Server packages using the special utility "unminimize", which returns components that are convenient for interactive management.

According to Canonical representatives, the deletion of the manual control functions resulted in the acceleration of the load time by 40% and the reduction of the occupied disk space by 50%. At the same time, this release remained completely compatible with all the packages from standard Ubuntu repositories. Required packages can be installed using the standard package manager apt or using snapd, which are included in the distribution by default.

Two assemblies are available for download, based on Ubuntu 16.04 LTS and 18.04 LTS. You can download them on the official website.