Aids to the User

Xselect has several on-line features to help the user. The first is the on-line help. To get help on a particular topic, just type

xsel > help topic

The only detail of note is that to get help on a compound command, you must surround the command name in double quotes to protect the spaces. For example:

xsel > help "command show events"

will give you the "events" subtopic of the help topic "show".

If you type ??, you will get a list of all the available commands.

The next useful command is the XPI command LPARM. This will list all the parameters that a given command takes, as well as their types, and current default values. It is very useful for reminding yourself of what options any given command has.

All the commonly used parameters will be prompted for, if not entered on the command line. It is often best, when you are not sure of the order of parameters in a command, to just type the command name and let Xselect prompt you for the values it wants. Whenever a given command has a number of subcommands (e.g. SHOW STATUS, SHOW DATA,...), Xselect will list the available subcommands before giving the prompt.

On UNIX systems, Xselect uses the READLINE command line interpreter. This supports command line editing, filename completion ( use the tab key, hit once it makes the longest unique completion, and if there is more than one completion, a second tab will show you all the possible options) and up and down arrow keys for command recall.

Finally, if you cannot remember the name of some file, or what exactly you called the directory where you stored your data, the $ command, with no arguments, will always break to the shell. You return to Xselect by typing exit, and you will come back at the point you left.

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Last modified: Tuesday, 10-Jan-2023 11:03:01 EST

HEASARC Staff Scientist Position - Applications are now being accepted for a Staff Scientist with significant experience and interest in the technical aspects of astrophysics research, to work in the High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. Refer to the AAS Job register for full details.