1, Windows system environment variables explain
% USERPROFILE% represents C: DocumentsandSettings current user name
% ALLUSERSPROFILE% represents C: DocumentsandSettingsAllUsers
% APPDATA% represents C: DocumentsandSettings current username ApplicationData
% ALLAPPDATA% represents C: DocumentsandSettingsAllUsersApplicationData
% SYSTEMDRIVE% represents C:
% HOMEDRIVE% represents C:
% SYSTEMROOT% representation C: Windows
% WINDIR% represents C: Windows
% TEMP% and% TMP% represents C: DocumentsandSettings current user name LocalSettingsTemp
% ProgramFiles% represents C: ProgramFiles
% CommonProgramFiles% represents C: ProgramFilesCommonFiles
set environment variables in two ways: the first is set in the command prompt window, run; the second is by clicking on "my The "Environment Variables" button of the Computer → Properties → Advanced tab is set. It should be noted that the first way to set environment variables is only valid for the current running window. After closing the running window, the setting will not work, and the second way to set environment variables is permanent.
2, how to set environment variables in the command prompt window?
after the "Start → Run" box, enter "cmd" press "OK" button, run the command window. Enter "set" at the command prompt to see the environment variable settings. To view the settings of a specific environment variable, for example to view the settings of the path environment variable, you can enter "setpath". To create an environment variable, such as to create an environment variable named aa with a value of "c:", you can enter the "setaa=c:" command. To delete an environment variable, such as to delete the aa environment variable, you can enter the "setaa=" command (note = no spaces after). How to change the settings of an environment variable? There are two ways to change the environment variable: one is the append mode, that is, the value of the variable is increased without changing the existing settings of the environment variable. For example, to add a value of "D:" to the environment variable aa, you can enter "setaa=%path%;D:". The other is a complete modification. For this method, we can implement it by directly creating an environment variable.
3, what is the relationship between user and system variables are variables?
click on "My Computer → Properties → Advanced" tab of the "Environment Variables" button, "Environment Variables" dialog box appears, the user Administrator user login system of the above, the dialog is as if the current Administrator Variables, below the dialog box are system variables (that is, user variables equivalent to all users in the system). Sometimes we will see that there is an environment variable in the user variable and system variable, such as path, then the value of path is the value in the user variable or the value in the system variable, or neither? The answer is that neither is. The value of the path variable is a superposition of the value in the user variable and the value in the system variable.
4, change the value of environment variables and environment variables should pay attention to what?
the value of environment variables and environment variables do not contain spaces, do not use Chinese, remember!