# Linux ## Is there any way to include JabRef in the start menu of Ubuntu? Yes, there is. See for details. ## JabRef does not start under Linux! What can I do? ### JabRef 5.x > JabRef 5.x requires Java 13 (It is included in the native builds) ### JabRef 4.x > JabRef requires Java 8 Please follow the steps provided on our [installation page](/v4/general/installation.md). JabRef 4.x does not run under Java 9 or newer. See You might see the error message `Error: Could not find or load main class org.jabref.JabRefMain`. This means, you do not have [JavaFX](https://en.wikipedia.org/wiki/JavaFX) support activated in your Java runtime environment. This typically happens if you use [OpenJDK](http://openjdk.java.net/), where one needs to setup [OpenJFX](https://wiki.openjdk.java.net/display/OpenJFX/Main) separately. ## I am on Debian/Ubuntu and clicking on the JabRef icon works, but I cannot start JabRef from the command line. What is wrong? You have several Java Virtual Machines installed, and under the command line the wrong one is chosen. Have a look at the previous question that tells you how to change the virtual machine used. For Ubuntu you may also have a look at the [Ubuntu page on Java](https://help.ubuntu.com/community/Java). ## Does JabRef run under free Java (Classpath, Kaffee, GCJ, etc.)? As far as we know, JabRef is not yet running on these free JVMs, due of our dependencies. However, JabRef is reported to run nicely on the [IcedTea](http://fedoraproject.org/wiki/Features/IcedTea) runtime, which is based on the [OpenJDK](http://openjdk.java.net/) built with [GNU Classpath](http://www.gnu.org/software/classpath/) to fill in missing classes. Some issues have been encountered with the look and feel (see issues [#393](https://github.com/JabRef/jabref/issues/393) and [#2003](https://github.com/JabRef/jabref/issues/2003)). Please let us know if newer versions give different results. If you have an idea or the expertise to make JabRef work under Classpath, let us know. ## Everything looks too big or too small. How can I change it to to a more reasonable size? In the background, JabRef uses [JavaFX](https://en.wikipedia.org/wiki/JavaFX). Applications using JavaFX can be scaled via `java -Dglass.gtk.uiScale=1.5 -jar .jar`. If you have installed JabRef via a package manager, you probably don't have a `.jar` file but a binary file. In this case, you need to find your `JabRef.cfg` in your installation folder (possibly located at `/opt/JabRef/lib/app/JabRef.cfg`) and add in the section `[JavaOptions]` the line `-Dglass.gtk.uiScale=1.5`. Then, restart JabRef. Try finding a value that is suitable for you. On high resolution displays, values around `1.5` seem to be reasonable. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.jabref.org/v4/faq/faqs-on-operating-systems/faqlinux.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.