Specifications

Version 2.0
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Figure 1 Variable substitution flow chart
3.6.1 Environment Variables
Environment variables are variables that can hold the user specified contents and can
be used on the command line or in scripts. Each environment variable has a case-
sensitive name (a C-style identifier) and a string value. Environment variables can be
either volatile (they will lose their value on reset or power-off) or non-volatile (they
will maintain their value across reset or power-off).
Environment variables can be used on the command-line by using %variable-name%
where variable-name is the environment variable’s name. Variable substitution is not
recursive. Environment variables can also be retrieved by a UEFI Shell command by
using the GetEnv() (see page 39) function.
Environment variables can be displayed or changed using the set shell command.
They can also be changed by a UEFI Shell command using the SetEnv() function.
The following table lists the environment variables that have special meaning to the
UEFI Shell: