Prior to starting a new SAS session, the SAS environment has to be initialized. This is done by means of one of the shell scripts created during the SAS software installation process (setsas.[c]sh; see § 1.1). The way this is done depends on the shell used. Assuming that the SAS software installation was done at:
/top_dir/xmmsas_YYYYMMDD_HHMM
the script can be executed as follows:
. /top_dir/xmmsas_YYYYMMDD_HHMM/setsas.sh [sh, bash, ksh] or source /top_dir/xmmsas_YYYYMMDD_HHMM/setsas.csh [csh, tcsh]
It is recommended to work in a directory different from that where SAS was installed. This way, analysis products do not mix with the SAS installation files.
The setsas.[c]sh script takes care of all the necessary environment setup required to work with SAS.
Some external tools are required to work with SAS. The URL,
http://www.cosmos.esa.int/web/xmm-newton/sas-requirements
provides detailed information on which these tools are and the versions required for a given SAS release. In recent versions of SAS, the HEASOFT software must be initialized prior to the initialization of SAS. Otherwise the SAS initialization will not be complete. Before the data analysis process can start, SAS has to know where the ODF and CCFs are.