ENVIRON Statement


 Example

 See the ENVIRON statement programming example, which uses the
 ENVIRON$ function.




 ENVIRON Statement
 ----------------------------------------------------------------------------


 Action

 Modifies or adds a parameter in the DOS or OS-2 environment-string table.


 Syntax

  ENVIRON  stringexpression$


 Remarks

 The argument  stringexpression$ is a string constant or variable that
 contains the name of the environment variable, such as PATH or PROMPT. It
 can have the form  parameterID= text, or  parameterID  text. Everything to
 the left of the equal sign or space is assumed to be a parameter, and
 everything to the right, text.

 The argument  parameterID must contain all uppercase letters. For example.
-----------------------------------------------------------------------------
 This statement.                         Has this effect.
 ----------------------------------------------------------------------------
 This statement.                         Has this effect.
 ----------------------------------------------------------------------------
 ENVIRON "PATH=C.\SALES"                 Changes the path.

 ENVIRON "path=C.\SALES"                 Does not change the path. (It
                                         creates a new environment
                                         parameter not usable by the
                                         operating system.)



 If  parameterID did not previously exist in the environment-string table, it
 is appended to the end of the table. If  parameterID exists in the table
 when the  ENVIRON statement is executed, it is deleted and the new
 parameterID value is appended to the end of the table.

 The text string is the new parameter text. If the text is a null string ("")
 or a semicolon (";"), the existing parameter is removed from the
 environment-string table and the remaining body of the table is compressed.

 DOS or OS-2 discards the environment-string table modified by this function
 when your program ends. The environment-string table is then the same as it
 was before your program ran.


 Note

 You cannot increase the size of the environment-string table when using the
 ENVIRON statement. This means that before you can add a new environment
 variable or increase the size of an existing environment variable you must
 first delete or decrease the size of existing environment variable(s).


 You can use this statement to change the PATH parameter for a "child"
 process (a program or command started by a  SHELL statement) or to pass
 parameters to a child process by creating a new environment variable.

 BASIC generates the error message Out of memory when no more space can be
 allocated to the environment-string table. The amount of free space in the
 table usually is quite small.


 See Also

  ENVIRON$,  SHELL Function


 Example

 The following example uses the  ENVIRON$ function to get a copy of the
 current DOS path variable. The path variable is then changed using the
 ENVIRON statement. The contents of the environment-string table are then
 displayed using the  ENVIRON$ function.

 DEFINT A-Z
 ' Initialize variables.
 Path$ = "PATH="
 I% = 1
 ' Store the old PATH.
 OldPath$ = ENVIRON$("PATH")
 ENVIRON "PATH=C.\BIN;C.\DOS;C.\BUSINESS\ACCOUNTING\RECEIVABLES\MAY"
 ' Display the entire environment-string table.
 PRINT "Your current environment settings are."
 PRINT
 DO WHILE ENVIRON$(I%) <> ""
     PRINT ENVIRON$(I%)
     I% = I% + 1
 LOOP
 ' Change the PATH back to original.
 ENVIRON Path$ + OldPath$
 ' Verify the change.
 PRINT
 PRINT "Your PATH has been restored to."
 PRINT
 PRINT ENVIRON$("PATH")