GWBASIC User's Manual

GW-BASIC User's Guide
ENVIRON Statement
Purpose:
To allow the user to modify parameters in GW-BASIC's environment string table. This may be to
change the path parameter for a child process, (see ENVIRON$, SHELL, and the MS-DOS
utilities PATH command), or to pass parameters to a child by inventing a new environment
parameter.
Syntax:
ENVIRON string
Comments:
string is a valid string expression containing the new environment string parameter.
string must be of the following form
parmid=text
where parmid is the name of the parameter such as PATH.
parmid must be separated from text by an equal sign or a blank. ENVIRON takes everything to
the left of the first blank or equal sign as the parmid; everything following is taken as text.
text is the new parameter text. If text is a null string, or consists only of a single semicolon,
then the parameter (including parmid=) is removed from the environment string table, and the
table is compressed. text must not contain any embedded blanks.
If parmid does not exist, then string is added at the end of the environment string table.
If parmid does exist, it is deleted, the environment string table is compressed, and the new string
is added at the end.
Examples:
Assuming the environment string table is empty, the following statement will create a default
path to the root directory on Disk A:
ENVIRON "PATH=A:\"
If your work subdirectory were john, you would be able to get DEBUG from the root.
A new parameter may be added:
ENVIRON "COMSPEC=A:\COMMAND.COM"
The environment string table now contains
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