Introduction

xshow is a simple tool for displaying continually updating values of keywords. It can also display keyword values graphically as a function of time. It is commonly used for updating text displays of important parameters for either the telescope subsystems or instruments.

Text Displays

To display keyword values in a text format, use the form:

xshow -s service key1 key2 key3 key4 key5

where service is the service name or keyword library name, such as "lris", "dcs", "ao", or "nirc". This is the same format as "modify" and "show" command access to keyword libraries. "key1" through "key5" are keywords within this library.

As an example, the following shows a DCS xshow screen, displaying RA, Dec, UTC, and various other useful parameters:

This was invoked by the command:

    xshow -s dcs lst ut ha ra dec airmass \
    poname targname axestat telfocus secfocus tubetemp domeposn az el parang \
    rotpposn rotposn

Note that the left column contains the keyword name, and the right column contains the value; the same information seen if you were to type "show -s dcs lst", except that the show command may have additional comments such as units after the value.

Also note that the two columns are always forced to have the same width. Very long keyword names or (more likely) values will force the window to resize to a large width, potentially with a lot of wasted white space.

The flag "-twocol" can be used to create a four-column (despite the flag name!) list, two columns each of (name, value) pairs. The end of this Web page discusses other command-line options.

Graphical Displays

xshow can alternatively display a time series of one keyword value.

Common Command-Line Options

xshow [-serv service_name].. [-twocol] [-noprime] [-nohead] [-noquit] [-histo [-aut]] keywords