# Runtime

The ABS runtime lets you customize how ABS scripts are interpreted, and exposes some useful global variables.

# ABS init file

When the ABS interpreter starts running, it will load an optional ABS script as its init file. The ABS init file path can be configured via the OS environment variable ABS_INIT_FILE. The default value is ABS_INIT_FILE=~/.absrc.

If the ABS_INIT_FILE exists, it will be evaluated before the interpreter begins in both interactive REPL or script modes. The result of all expressions evaluated in the init file become part of the ABS global environment which are available to command line expressions or script programs.

Have a look at an example ABS init file (opens new window).


The ABS_INTERACTIVE global environment variable is pre-set to true or false so that the init file can determine which mode is running. This is useful if you wish to set the ABS REPL command line prompt or history configuration variables in the init file. This will preset the prompt and history parameters for the interactive REPL (see REPL Command History above).

$ abs
Hello user, welcome to the ABS programming language!
Type 'quit' when you're done, 'help' if you get lost!