B. The Command Line Interface

Xselect v3.0 replaced the old XPI command-line interface with a built-in command interpreter. Its behaviour will be familiar to XPI users: it is not case sensitive, commands and parameter names can be abbreviated to the shortest unique string, and it provides scripting, logging, history recall and alias facilities. Parameters are managed by APE, the standard HEASoft parameter interface, so Xselect follows the same parameter-file conventions as the other FTOOLS.

The UNIX version also inherits the nice command line editing features of the READLINE library, which has an EMACS like syntax for command line searches, and supports up and down arrow history recall, and filename completion using the tab key.

There are some magic characters, which are captured in the parser, and so they must be surrounded by double quotes to be passed through as part of an argument.

In most cases, the parser is fairly forgiving, so you do not need too detailed a knowledge of it. For all practical purposes, you only need to know what the magic characters are (see Special Characters), and the general syntax of the command line.