When NESL is started, it loads the file .nesl (if it exists) from your home directory. This file should be in the same format as any NESL file--it can contain definitions as well as top-level commands. It is typically used to modify environment defaults such as the preferred configuration (set config) , memory size (set memory_size) , editor (set editor) , and maximum print length for sequences returned at the top level (set print_length) . These commands are all described later in this manual.