Differences

This shows you the differences between two versions of the page.

--- other:x_conf [2022/08/08 15:39] – [Configuration on the remote machine] jypeter
+++ other:x_conf [2022/08/09 10:53] – [Using an X server on Linux] jypeter
@@ Line 3: / Line 3: @@
 ===== What is an X server? =====
-An //X server// is not a server for distributing your perfect models output!
+  * An //X server// **is not** a server for distributing your perfect models output!
-An //X server// is basically a program running on your local computer that understands the [[https://en.wikipedia.org/wiki/X_Window_System_core_protocol|X Windows System protocol]] used by **remote Linux servers** to generate graphics, and that can //render// (i.e. display) the graphics generated remotely on your **local computer**.
+  * An //X server// **is** basically a program running on your **local** computer that understands the [[https://en.wikipedia.org/wiki/X_Window_System_core_protocol|X Windows System protocol]] used by **Linux computers** (**local** computer, or **remote** Linux servers) to generate graphics, and that can //render// (i.e. display) the graphics generated **remotely** on your **local** computer
+===== What do we mean exactly with Local and Remote computers? =====
+This page will very often mention **local computers** or **remote computers**:
+  * The **local computer** is the desktop or laptop you are interacting with (using a screen+mouse+keyboard)
+    * The local computer can be a **Linux, Windows or Mac (i.e //OS X//) computer**
+  * The **remote computer or server** is another computer that you also want to interact with (using the screen+mouse+keyboard of your local computer)
+    * We only consider on this page the case of a **remote //Linux// machine** that **requires a local running //X server//**
+  * **Remote Linux machine** can mean several things:
+    * It can be another operating system running inside **a [[https://en.wikipedia.org/wiki/Virtual_machine|Virtual Machine]] on your local computer**
+      * We mostly consider on this page the case of a **Linux virtual machine** using [[other:win10wsl|Windows Subsystem for Linux (WSL)]] on a Windows computer, but this can apply to other configurations
+    * It can be a **distant computer** or server in your building, or a high performance computer in a computing center on the other side of the Earth. It could also be a virtual machine in the //Cloud//
 ===== Using an X server on Linux =====
-Linux computers come pre-configured with a running //X server// that will display the graphics generated locally and on remote Linux servers
+<WRAP center round tip 60%>
+You don't need to do anything special!
+</WRAP>
-**You don't need to do anything special!**
+Linux computers come pre-configured with a running //X server// that will display the graphics generated locally and on remote Linux servers
@@ Line 82: / Line 99: @@
 ===== Configuration on the remote Linux server =====
-==== If you are connecting with ssh ====
+==== If you are connecting with ssh or PuTTY ====
-Nothing special to do if you are using [[other:ssh#using_an_x_server_to_display_graphics|"ssh -X" or "ssh -Y"]]
+Nothing special to do, if you are using [[other:ssh#using_an_x_server_to_display_graphics|"ssh -X" or "ssh -Y"]] or ''PuTTY'' to connect to a remote Linux server
 ==== If you are using WSL ====
-If you have installed [[other:win10wsl|WSL+Ubuntu]] on your local machine, and you need your //X server// to display local graphics generated in WSL, you need to **define the ''DISPLAY'' variable** in your terminal:
+You need to know what you consider as the //Local machine//, and what is the //Remote server//
-  * //bash// shell: ''export DISPLAY=localhost:0.0''
-  * //tcsh// shell: ''setenv DISPLAY localhost:0.0''
+  * **Local machine**: your local **Windows computer**, where you have installed [[other:win10wsl|WSL+Ubuntu]]
-  * You probably want to define the ''DISPLAY'' variable automatically in one of the shell configuration files
+  * **Remote server** : we consider 2 types of remote servers:
+    * an **actual remote server**
+    * The **WSL computer** running on a **virtual machine inside your local Windows computer**. This can be considered as a different and //remote// computer, even it is running on the local computer\\ You need your local //X server// to display graphics generated in WSL
+    * **Define the ''DISPLAY'' variable** in the terminals used in WSL:
+      * //bash// shell: ''export DISPLAY=localhost:0.0''
+      * //tcsh// shell: ''setenv DISPLAY localhost:0.0''
+      * You probably want to define the ''DISPLAY'' variable automatically in one of the shell configuration files
@@ Line 164: / Line 188: @@
 ==== On a Windows computer with WSL+Linux and an X server installed ====
+We assume that [[other:win10wsl|WSL+Ubuntu]] is installed and that the ''DISPLAY'' variable is [[other:x_conf#if_you_are_using_wsl|configured correctly]]
-  * FIXME ''export DISPLAY=localhost:0.0''
+Open a WSL terminal (you should know how, if you have installed WSL) and type some basic commands
+<code>[Local WSL] $ hostname
+name_of_your_local_machine
+[Local WSL] $ echo $DISPLAY
+localhost:0.0
+[Local WSL] $ xterm
+[Local WSL] $ ssh -X some_login@some_remote_server
+[some connection information skipped here]
+[Remote] $ echo $DISPLAY
+localhost:22.0
+[Remote] $ xterm</code>
 ===== Troubleshooting =====
@@ Line 179: / Line 215: @@
   * Have you configured [[other:putty_conf|PuTTY]] and/or other required applications correctly ?
   * Is the ''DISPLAY'' variable defined correctly on the local and remote computer?
+=== When DISPLAY is not defined correctly ===
+If the ''DISPLAY'' **variable is not defined (correctly)**, you will get a ''Can't open display: //[NO VALUE DISPLAYED HERE]//'' error
+<code>$ xterm &
+$ xterm: Xt error: Can't open display:
+xterm: DISPLAY is not set
+$ echo $DISPLAY
+</code>
+Make sure that you are using ''ssh -X'' or ''ssh -Y'', or that [[other:putty_conf#changing_some_useful_settings|PuTTY is configured]] with ''Enable X11 forwarding''
+=== When there is no X server running ===
+If the ''DISPLAY'' variable is defined, but there is **no X server**, you will get a ''Can't open display: localhost://[SOME VALUE]//'' error\\ <code>$ xterm &
+$ connect localhost port 6000: Connection refused
+xterm: Xt error: Can't open display: localhost:12.0</code>
+Time to [[other:x_conf|read this page again]]...
 ==== OpenGL related settings ====