System environment variables
System environment variables can be viewed from Control Panel bychoosing the System icon. These variables are always set no matter whologs on and they cannot be changed by any user.
There are a few additional predefined environment variables that areset when the user logs on that do not appear in the System dialog box:
USERNAME USERDOMAIN NTVERSION (not available in Windows NT 4.0 anymore) WINDIR OS PROCESSOR_ARCHITECTURE
values: x86, MIPS or ALPHA
values for x86: 3, 4, 5 values for MIPS: 3000, 4000 values for ALPHA: 21064
HOMEPATH HOMEDRIVE HOMESHARE
These three environment variables are set based on the value of the home directory. The user's home directory is specified in User Manager (Choose Profile and Properties). If the home directory uses universal naming conventions (UNC), then they will have the following values:
HOMESHARE=\\<server name>\<share name> HOMEPATH=\<path> HOMEDRIVE=<drive letter>:
If the home directory is a local path such as c:\nt then they will look like this:
HOMEDRIVE=c: HOMESHARE= HOMEPATH=\nt
All above environment variables are always present and therefore maybe used in log on scripts.
User environment variables
User environment variables can be viewed from Control Panel as well.The user may add, delete or modify the environment variables in theUser Environment Variables for User field. These variables takeprecedence over system environment variables. The user path isappended to the system path.
AUTOEXEC.BAT environment variables
All environment variables and the paths set in the AUTOEXEC.BAT fileare used to create the Windows NT environment. Any paths in theAUTOEXEC.BAT file are append to the system path.
How environment variables are set
Environment variables are set in the following order:
- System variables
- AUTOEXEC.BAT variables
- User variables
How the path is built
The Path is constructed from the system path, which can be viewed inthe System Environment Variables field in the System dialog box. TheUser path is appended to the system path. Then the path from theAUTOEXEC.BAT file is appended.
Note: The environment variables LibPath and Os2LibPath are built thesame way (system path + user path + AUTOEXEC.BAT path).
Changing user environment variables by using Control Panel
User environment variables can be added, changed or deleted fromControl Panel. There is no need to reboot after making any of thesechanges. Changes take effect immediately after exiting the Systemdialog box.
The next application you start will use the new settings. All otherapplications running before the changes were made will not recognizethe changes.