There are several shell variables which are used by Ab Initio. Unsurprisingly, they all begin with the prefix AB_ and, as is common Unix practice, are all upper case. It is normal to set all of these in the user's abinitio.rc file.

• AB_AIR_ROOT The directory where the EME repository resides
• AB_ALLOW_PROJECT_OVERVIEW When this is set, the EME will show the relationship between all graphs and datasets in a project. Deprecated as of version 2.14
• AB_HOME The directory where the Air tool resides
• AB_MAX_RECORD_BUFFER Defines the size of the buffer used for reading records. This is generally set to an impossibly high number so that if you see it overflowing, you probably have an invalid record definition or something wrong with the data.
• AI_SERIAL_LOG Where to send the run-log for a session. set to /stdout to display messages on the console.