To check if you have Java installed, type this in a terminal window:

java -version


Version 11 is recommended, but 8 and 15 is also ok. If the command above gives an error about something missing you need to install Java Runtime Environment (JRE). It is recommended to install the whole Java Develoment Kit (JDK) which includes the JRE from here https://adoptopenjdk.net/

You should also download the reqT.jar and when you run it using java -jar reqT.jar the following output shold be shown. The latest version of reqT as shown below is needed for later java versions.

$ java -jar reqT.jar

** Welcome to reqT version 3.1.5
** Snapshot build number: 567
** Scala version 2.12.13
** Java  version 11.0.9.1 OpenJDK 64-Bit Server VM

**                  _______
**                 |__   __|
**   _ __  ___   __ _ | |      reqT - a requirements engineering tool
**  |  __|/ _ \ / _  || |      reqT.org
**  | |  |  __/| (_| || |      (c) 2010-2019, Lund University
**  |_|   \___| \__  ||_|      Open Source BSD-2-clause license
**                 | |
**                 |_|

** Type  edit      to start model editor gui
** Type  :help     for help on the Scala interpreter
** Type  :pa       to enter paste mode
** Type  :q        to exit when all sub-threads are done
** Type  sys.exit  to exit and terminate all threads
** Type  Feature?  to get help on a concept, e.g. Feature

reqT>