sherpa

Starting Sherpa

From the CIAO command line, type:

unix% sherpa [-x|-b|-l|-n] <file>

Any or all of the following options which may be supplied when Sherpa is started:

• -x : launch Sherpa shell in separate display terminal.
• -b : runs Sherpa in batch mode
• -l : specifies which language to use, "slang" or "python".
• -n : prevents the Sherpa banner from being displayed on startup.
• <file>: a file of S-Lang or Python Sherpa commands to run

The startup script loads the Sherpa module, as well as the CRATES module, which handles file input and output ("ahelp crates"), and the Chips module, used for customizing the plots ("ahelp chips").

The language to use - S-Lang or Python - is determined by the hierarchy:

• language specified by the "-l" command-line option
• CHIPS_SCRIPT_LANG environment variable.
• SHERPA_SCRIPT_LANG environment variable (see "ahelp ciaorc")
• "shell" preference in the $HOME/.sherpa.rc file
• if none of the above are set, default to PYTHON

The "Starting Sherpa" thread has more details.

The Sherpa Resource File: .sherpa.rc

When Sherpa is started, it processes the $HOME/.sherpa.rc resource file. The resource file defines default behavior for the Sherpa commands and can be customized to the user's preferences; refer to "ahelp sherparc" for details.

Loading Modules in Python

To import the Sherpa, CRATES, and Chips modules in Python without using the "sherpa" startup script:

from sherpa.astro.ui import *
from pychips.hlui import *
from pycrates import *

Loading Modules in S-Lang

To import the Sherpa, CRATES, and Chips modules in S-Lang without using the "sherpa" startup script:

require("sherpa");
require("chips_hlui");
require("crates");

Getting Help

There are several ways to access the Sherpa help files.

From the CIAO command line:

o) Syntax, description and examples for a specific command:

unix% ahelp <command>

List of all Sherpa help files by context:

unix% ahelp -c py.sherpa

or

unix% ahelp -c sl.sherpa

From within Python or S-Lang, ahelp may be called two ways:

o) Python:

sherpa> ahelp("<command>")

sherpa> !ahelp <command>

o) S-Lang:

sherpa> ahelp("<command>");

sherpa> !ahelp <command>;

The native help systems - called "help" in both cases - may also be used to obtain syntax information:

# Python
sherpa> help <command>

# S-Lang
sherpa> help <command>;

CHANGES IN CIAO 4.1

Startup Option

The "-l" command-line option may be specified when ChIPS is started to select the language; see the text for details.