In the previous section you got to know how to do a YaST program. Well, normally YCP-scripts are executed involving the whole YaST-machinery, e.g. during installation, which requires correct embedding of the script into the surrounding YCP environment. Fortunately there is a way to let run YCP-scripts isolated, i.e. stand-alone.

To do so we make use of the architectural separation of components featured by YaST. The “command line version” of YaST is called y2base and can usually be found in /usr/lib/YaST2/bin. You could set the PATH to include this location to avoid typing in the full path every time.

$> y2base -h

Usage: y2base [LogOpts] Client [ClientOpts] Server [Generic ServerOpts] [Specific ServerOpts]
LogOptions are:
    -l | --logfile LogFile    : Set logfile
ClientOptions are:
    -s                        : Get options as one YCPList from stdin
    -f FileName               : Get YCPValue(s) from file
    '(any YCPValue)'          : Parameter _IS_ a YCPValue
Generic ServerOptions are:
    -p FileName               : Evaluate YCPValue(s) from file (preload)
    '(any YCPValue)'          : Parameter _IS_ a YCPValue to be evaluated
Specific ServerOptions are any options passed on unevaluated.

Examples:
y2base installation qt
    Start binary y2base with intallation.ycp as client and qt as server
y2base installation '("test")' qt
    Provide YCPValue '"test"' as parameter for client installation
y2base installation qt -geometry 800x600
    Provide geometry information as specific server options

This help page, showing the possible options in a call of y2base, is rather self-explaining. For the moment the interesting parameters are Client and Server. In Section 2.4, “External Programs” we learned that YaST consists of several modules, some of them being client-components and some others being server-components. By invoking YaST in the way displayed above we can connect any client-component with any server-component.

Because a YCP-program (also called YCP-module) can act as a client-component, it is possible to connect it with a server-component suitable of executing it. Since our “Hello, World!”-program displays something on screen, we need to use the UI as server-component in this case. As already said the UI is able to use a text-based console environment as well as a graphical X11 environment which leads to the following two methods of running a YCP-script.