# Environment variables used by Sage¶

Sage uses several environment variables when running. These all have sensible default values, so many users won’t need to set any of these. (There are also variables used to compile Sage; see the Sage Installation Guide for more about those.)

• DOT_SAGE – this is the directory, to which the user has read and write access, where Sage stores a number of files. The default location is ~/.sage/, but you can change that by setting this variable.

• SAGE_RC_FILE – a shell script which is sourced after Sage has determined its environment variables. This script is executed before starting Sage or any of its subcommands (like sage -i <package>). The default value is $DOT_SAGE/sagerc. • SAGE_STARTUP_FILE – a file including commands to be executed every time Sage starts. The default value is $DOT_SAGE/init.sage.

• SAGE_SERVER – only used for installing packages. Alternative mirror from which to download sources, see the Installation Guide for details.

• BROWSER – on most platforms, Sage will detect the command to run a web browser, but if this doesn’t seem to work on your machine, set this variable to the appropriate command.

# Relevant environment variables for other packages¶

This is a non-exhaustive list of environment variables which influence some package contained within the SageMath distribution.

In many cases, SageMath uses a custom default value if the variable is not set, which is not the same default that the system-wide package would use. So, if you would like to use your system-wide configuration, you need to explicitly set the environment variable to the system-wide default.