Archive:Getting Started/Run/Shell

Revision as of 20:41, 29 June 2011 by Neverendingo (Talk | contribs) (Text replace - "<code bash>" to "<syntaxhighlight lang="bash">")

Jump to: navigation, search


Using the normal shell with sux

For this method, the tool sux ( is required. sux is available on most distributions. Otherwise you could rely on the normal shell without sux method below. sux allows you to change to another user with an implicit managing of the X forwarding details (authentication and DISPLAY exporting) in a clean and simple way.

To login, type
sux - kde-devel</code>

All environment variables and everything else should be set up correctly by your {{path|[[Getting_Started/Increased_Productivity_in_KDE4_with_Scripts/.bashrc|.bashrc]]}}. To start an application, simply type it's name; for example <syntaxhighlight lang="bash">kwrite</code>
{{Note|If you get errors about missing mimetypes or such, try running the following:<syntaxhighlight lang="bash">unset XDG_DATA_DIRS ; kbuildsycoca4</code>

== Using the normal shell without sux ==
The simplest method to launch KDE 4 applications is using <tt>su</tt> to login as the <tt>kde-devel</tt> user and then simply start any KDE 4 application from command line. To login, type
<syntaxhighlight lang="bash">su - kde-devel</code>
and then, after entering your password
<syntaxhighlight lang="bash">export DISPLAY=:0</code>
{{Note|Exporting the <tt>DISPLAY</tt> variable is necessary so that the KDE 4 applications appear on your normal KDE 3 desktop.}}
All environment variables and everything else should be set up correctly by your {{path|[[Getting_Started/Increased_Productivity_in_KDE4_with_Scripts/.bashrc|.bashrc]]}}. To start an application, simply type it's name; for example <syntaxhighlight lang="bash">kwrite</code>
If you get errors about missing mimetypes or such, try the following:
* run <syntaxhighlight lang="bash">unset XDG_DATA_DIRS ; kbuildsycoca4</code>
If you get an error about not being able to connect to an X server, be sure to issue
<syntaxhighlight lang="bash">sudo xhost +local:kde-devel</code>
as your regular KDE 3 user to ensure that the application can connect to your current X session.

Although your X server should accept incoming TCP connections, this is often switched off as a distribution default (like with Kubuntu Feisty). When using <tt>kdm</tt> you must edit <tt>/etc/kde3/kdm/kdmrc</tt> as root and make sure it does not contain:
<code>ServerArgsLocal=-nolisten tcp</code>
Once you have fixed this, you will need to restart your X server. The <tt>xhost</tt> command should no longer return an "unable to open display" error.

For convenience, you should put this in the Autostart of your regular user. To do this, create a new file in the <tt>$HOME/.kde/Autostart</tt> directory of your regular user with the following content:
<syntaxhighlight lang="bash">
#! /bin/sh
xhost +local:kde-devel
Make sure that the new file is executable by using <tt>chmod +x</tt> on it.

If you'd like to find out more about the '''security issues''' involved with using <tt>xhost</tt>, see [ this article]

== Using SSH ==

The simplest way to run a KDE 4 application with SSH in your current desktop environment is to get an X-aware shell prompt as the <tt>kde-devel</tt> user like this:
<syntaxhighlight lang="bash">ssh -X kde-devel@localhost</code>
Now you can launch KDE apps as usual, for example:
<syntaxhighlight lang="bash">kwrite</code>
The two lines can be conveniently combined:
<syntaxhighlight lang="bash">ssh -X kde-devel@localhost kwrite</code>

If this gives you any errors, try the troubleshooting tips from the section above.
If you receive something like "kwrite: cannot connect to X server", open /etc/ssh/sshd_config and enable the "X11Forwarding" key.  Restart sshd and it should work fine.

=== Passwordless login ===
Before anything serious can be done using this method, a passwordless login needs to be set up. To start, run the following command as the regular desktop user:
<syntaxhighlight lang="bash">ssh-keygen -t rsa</code>
Hit enter three times to accept the path of {{path|~/.ssh/id_rsa}} and an empty passphrase. Now, copy the single line in {{path|~/.ssh/}} that's printed after running this command:
<syntaxhighlight lang="bash">cat ~/.ssh/</code>
After that line is copied, <tt>ssh</tt> back into the <tt>kde-devel</tt> user and put the copied line in the file {{path|$HOME/.ssh/authorized_keys}}:
<syntaxhighlight lang="bash">ssh -X kde-devel@localhost $HOME/kde/bin/kwrite \
Paste in the line, save the file, and quit KWrite.

Next make sure {{path|$HOME/.ssh/authorized_keys}} has the correct permissions:
<syntaxhighlight lang="bash">ssh kde-devel@localhost chmod og-xrw ~kde-devel/.ssh/authorized_keys</code>
Now try running KWrite again with the same SSH command; you shouldn't have to enter a password anymore:
<syntaxhighlight lang="bash">ssh -X kde-devel@localhost $HOME/kde/bin/kwrite</code>

{{warning|Using a passwordless SSH login has certain '''security risks''', so make sure you protect your <tt>~/.ssh/id_rsa</tt> file by restricting access to it with 
<syntaxhighlight lang="bash">chmod og-xrw ~/.ssh/id_rsa</code>(although the file should have these permissions when it is created)}}

=== The SSH desktop file ===
If you want to be able to launch apps more easily than running them with an SSH command from the command line, one way is to create <tt>.desktop</tt> files that <tt>ssh</tt> into the other account. 
{{Note|This will only be useful if your desktop environment supports .desktop files, but at least KDE and GNOME do.}}

You can start with an existing .desktop file as a template (like one from your desktop) or you can make one from scratch. The main idea is to prefix the command being run with this string:
<syntaxhighlight lang="bash">
ssh -X kde-devel@localhost $HOME/kde/bin/

A simple .desktop file that runs KWrite would have the following contents:

<syntaxhighlight lang="ini">
[Desktop Entry]
Exec=ssh -X kde-devel@localhost /home/kde-devel/kde/bin/kwrite %U
GenericName=Text Editor
Name=KWrite (kde-devel)

{{tip|Apps launched using SSH like this don't trigger the correct launch responses, so you probably want to disable "launch feedback" for your .desktop files}}

{{note|In order to create a .desktop file for a KDE 4 app by using this pattern, the app's package will have to have been installed into <tt>~/kde/bin</tt> using the <tt>cmakekde</tt> command}}


Content is available under Creative Commons License SA 4.0 unless otherwise noted.