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--- other:x_conf [2022/08/04 09:17]
jypeter created
+++ other:x_conf [2022/08/08 15:49]
jypeter [Nothing works!] Improved
@@ Line 5: / Line 5: @@
 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 the **remote Linux servers** to generate graphics, and that can //render// (i.e. display) the graphics 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 **remote Linux servers** to generate graphics, and that can //render// (i.e. display) the graphics generated remotely on your **local computer**.
 ===== Using an X server on Linux =====
-Nothing to do! Linux computers come pre-configured with a running X server (because they need it for displaying local graphics)
+Linux computers come pre-configured with a running //X server// that will display the graphics generated locally and on remote Linux servers
+**You don't need to do anything special!**
@@ Line 16: / Line 18: @@
 There are several options available
+==== Installing VcXsrv ====
+<note tip>''VcXsrv'' is **pre-installed on the LSCE Windows computers**!
+  * You may want to check if a more recent version is available
+  * You surely want to follow the configuration steps, in order to get the best possible settings to work with PuTTY!
+</note>
+Type: <wrap em>free</wrap>
+Download the installer from [[https://sourceforge.net/projects/vcxsrv/|VcXrsv]] and install ''VcXsrv''.
+=== VcXsrv Configuration ===
+You need to configure ''VcXsrv'' to work in //multiple windows// mode. The following steps will show you how to create a shortcut on your desktop to start VcXsrv in this appropriate mode
+  * Start the //configuration tool//: ''Start'' => ''VcXsrv'' => ''Xlaunch''
+  * Select ''Multiple windows'', then ''Next''
+  * Select ''Start no client'', then ''Next''
+  * Keep the default ''Clipboard'' settings, uncheck ''Native opengl'', then ''Next''
+    * You can check the [[other:x_conf#opengl_related_settings|OpenGL discussion section]] if you have time...
+  * Click on ''Save configuration'' and save an ''X_Server.xlaunch'' configuration file on your Desktop, then ''Terminate''.\\ You should now have a new ''X_Server'' icon/shortcut on your Desktop
+  * Start the server by double-clicking on the new ''X_Server'' icon
+    * It will seem that nothing happens, but an ''X'' icon will appear in the right side of the taskbar (you may have to look for it in the //Display hidden icons// pull-up menu). Your computer is now ready to display remote graphics!\\ {{ :other:vcxsrv_x.png?direct |}}
+    * The X server will stop when you close your Windows session or restart the computer. Do not forget to click on the ''X_Server'' icon on your desktop if you know that you will need an X server later
+      * FIXME Document how to automatically start the X server...
+    * Note: you can right-click on the ''X'' icon and select ''Exit...'' if you need to quit the X server
+==== Installing x410 ====
+<WRAP center round tip 60%>
+[[https://token2shell.com/x410/|x410]] is a **low cost** commercial //X server// that can be directly installed from the [[https://www.microsoft.com/store/productId/9NLP712ZMN9Q|Microsoft store]].
+This is an //X server//, and you will get the same functionalities as what is already provided for free by [[other:x_conf#installing_vcxsrv|VcXsrv]], **but**:
+  * Once installed, ''x410'' will be automatically updated by the Microsoft Store application
+  * If you move to another computer, you can install ''x410'' again by just [[other:win10config#connecting_to_the_microsoft_store|Connecting the MS Store to your account]] on the new computer. No need to buy it again
+  * There seem to be more (useful) updates than for ''VcXsrv''
+  * The interface is more modern, with more options, and there is a lot of useful information on the web site
+  * The ''x410'' name is easier to remember! :-D
+</WRAP>
+Type: <wrap em>commercial</wrap>
+Buy and install ''x410'' from the [[https://www.microsoft.com/store/productId/9NLP712ZMN9Q|Microsoft store]]
+=== x410 configuration ===
+  * Start ''x410'': ''Start'' => ''X410''
+    * It will seem that nothing happens, but an ''X'' icon will appear in the right side of the taskbar (you may have to look for it in the //Display hidden icons// pull-up menu). Your computer is now __almost__ ready to display remote graphics!\\ {{ :other:x410_x.png?direct |}}
+  * Right-click on the ''X'' icon to open the **X410 settings**
+    * Select ''Auto copy to Windows after selection''\\ {{ :other:x410_settings.png?direct |}}
+  * It's possible to **automatically start ''x410''**! Otherwise, it will stop when you close your Windows session or restart the computer, and you will have to restart it by hand (''Start'' => ''X410'') if you know that you will need an X server later
+    * Open the **Windows Task Manager** (Right-click on ''Start'' and select ''Task Manager'')
+    * Go to the ''Startup'' panel (if there are no panels, select ''More details'')
+    * Right-click on ''X140'' and select ''Enabled''
+  * Note: if you need to quit the //X server//, you can right-click on the ''X'' icon, and then click on the //Display// number at the lower left (usually ''0'') and select ''Shut down''
 ===== Using an X server on an Apple computer =====
+===== Configuration on the remote Linux server =====
+==== 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"]] or ''PuTTY'' to connect to a remote Linux server
+==== If you are using WSL ====
+You need to know what you consider as the //Local machine//, and what is the //Remote server//
+  * **Local machine**: your local **Windows computer**, where you have installed [[other:win10wsl|WSL+Ubuntu]]
+  * **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
+===== Testing =====
+The idea is to:
+  * Open a terminal and check that the ''DISPLAY'' environment variable is correctly defined on the local machine
+  * Connect to the remote machine
+  * Check that a (new) ''DISPLAY'' variable is automatically defined on the remote machine
+  * Check that you can start an application using graphics (e.g. ''xterm'') on the remote machine
+==== On a Linux computer ====
+Some basic commands in a terminal
+<code>[Local] $ hostname
+name_of_your_local_machine
+[Local] $ echo $DISPLAY
+:0
+[Local] $ ssh -X some_login@some_remote_server
+[some connection information skipped here]
+[Remote] $ hostname
+name_of_the_remote_server
+[Remote] $ echo $DISPLAY
+localhost:20.0
+[Remote] $ xterm</code>
+==== On a Windows computer with only an X server installed ====
+We just open a ''Powershell'' window (''Start'' => ''Windows Powershell'' => ''Windows Powershell'') and type some basic commands
+<code>PS C:\> $env:computername
+name_of_your_local_machine
+PS C:\> $env:DISPLAY
+PS C:\> $env:DISPLAY="localhost:0"
+PS C:\> $env:DISPLAY
+localhost:0
+PS C:\> ssh -Y some_login@some_remote_server
+Warning: No xauth data; using fake authentication data for X11 forwarding.
+[some connection information skipped here]
+[Remote] $ hostname
+name_of_the_remote_server
+[Remote] $ echo $DISPLAY
+localhost:19.0
+[Remote] $ xterm</code>
+==== On a Windows computer with PuTTY and an X server installed ====
+We assume here that [[other:putty_conf|PuTTY is already installed and configured]] and **correctly** configured (with ''Enable X11 forwarding'')
+We just have to open a pre-configured //PuTTY Session// on a remote server
+<code>[Remote] $ hostname
+name_of_the_remote_server
+[Remote] $ echo $DISPLAY
+localhost:19.0
+[Remote] $ xterm</code>
+==== 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]]
+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 =====
+==== Nothing works! ====
+That's unfortunate, but:
+  * Have you turned on your computer?
+  * Do you have network access, and an account on a remote server?
+  * Have you run the [[other:x_conf#testing|Tests]]?
+  * Have you installed and configured the //X server// correctly? Is it really running?
+  * 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 ====
+It's hard to know what the best //OpenGL// settings for your //X server// are: it depends on your local computer, the remote computer, the network speed, the application generating the graphics, the libraries' versions...
+  * If ''Native opengl'' is activated in ''VcXsrv'', you //may// have to also use the following environment variable on the remote computer: ''export LIBGL_ALWAYS_INDIRECT=1''
+    * or maybe not! You can try to understand the [[https://unix.stackexchange.com/questions/1437/what-does-libgl-always-indirect-1-actually-do|What does LIBGL_ALWAYS_INDIRECT=1 actually do?]] thread...
+==== Blurry display ====
+  * If you use ''VcXsrv'' and the content of some displayed //X windows// appear **blurry**, see if you can [[other:win10misc#vcxsrv_x_server|fix the compatibility settings]], or try to use **x410**.

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