Reads the value of an environment variable from the environment table of the calling process.
The function environment-variable
reads the environment variable specified by name and returns its value, or nil
if the variable could not be found.
A setf
method is also defined, allowing you to set the value of an environment variable:
(setf (environment-variable name) value)
If value is a string, then name is set to be value. If value is nil
then name is removed from the environment table.
In this first example the value of the environment variable PATH
is returned:
(environment-variable "PATH")
The result is a string of all the defined paths:
"c:\\hqbin\\nt\\x86;c:\\hqbin\\nt\\x86\\perl;c:\\hqbin\\win32;c:\\usr\\local\\bin;C:\\WINNT35\\system32;C:\\WINNT35;;C:\\MSTOOLS\\bin;C:\\TGS3D\\PROGRAM;c:\\program files\\devstudio\\sharedide\\bin\\ide;c:\\program files\\devstudio\\sharedide\\bin;c:\\program files\\devstudio\\vc\\bin;c:\\msdev\\bin;C:\\WINDOWS;C:\\WINDOWS\\COMMAND;C:\\WIN95\\COMMAND;C:\\MSINPUT\\MOUSE"
In the second example, the variable MYTZONE
is found not to be in the environment table:
(environment-variable "MYTZONE")
NIL
It is set to be GMT
using the setf
method:
(setf (environment-variable "MYTZONE") "GMT")
LispWorks User Guide and Reference Manual - 20 Sep 2017