參考自 https://ss64.com/nt/syntax-variables.html
Standard (built-in) Environment Variables
| Variable | Volatile (Read-Only) | Default value assuming the system drive is C: |
|---|---|---|
| ALLUSERSPROFILE | C:\ProgramData | |
| APPDATA | C:\Users\{username}\AppData\Roaming | |
| CD | Y | The current directory (string). |
| ClientName | Y | Terminal servers only – the ComputerName of a remote host. |
| CMDEXTVERSION | Y | The current Command Processor Extensions version number. (NT = “1”, Win2000+ = “2”.) |
| CMDCMDLINE | Y | The original command line that invoked the Command Processor. |
| CommonProgramFiles | C:\Program Files\Common Files | |
| COMMONPROGRAMFILES(x86) | C:\Program Files (x86)\Common Files | |
| COMPUTERNAME | {computername} | |
| COMSPEC | C:\Windows\System32\cmd.exe or if running a 32 bit WOW – C:\Windows\SysWOW64\cmd.exe | |
| DATE | Y | The current date using same region specific format as DATE. |
| ERRORLEVEL | Y | The current ERRORLEVEL value, automatically set when a program exits. |
| FPS_BROWSER_APP_PROFILE_STRING FPS_BROWSER_USER_PROFILE_STRING | Internet Explorer Default These are undocumented variables for the Edge browser in Windows 10. | |
| HighestNumaNodeNumber | Y (hidden) | The highest NUMA node number on this computer. |
| HOMEDRIVE | Y | C: |
| HOMEPATH | Y | \Users\{username} |
| LOCALAPPDATA | C:\Users\{username}\AppData\Local | |
| LOGONSERVER | \\{domain_logon_server} | |
| NUMBER_OF_PROCESSORS | Y | The Number of processors running on the machine. |
| OS | Y | Operating system on the user’s workstation. |
| PATH | User and System | C:\Windows\System32\;C:\Windows\;C:\Windows\System32\Wbem;{plus program paths} |
| PATHEXT | .COM; .EXE; .BAT; .CMD; .VBS; .VBE; .JS ; .WSF; .WSH; .MSC Determine the default executable file extensions to search for and use, and in which order, left to right. The syntax is like the PATH variable – semicolon separators. | |
| PROCESSOR_ARCHITECTURE | Y | AMD64/IA64/x86 This doesn’t tell you the architecture of the processor but only of the current process, so it returns “x86” for a 32 bit WOW process running on 64 bit Windows. See detecting OS 32/64 bit |
| PROCESSOR_ARCHITEW6432 | =%PROCESSOR_ARCHITECTURE% (but only available to 64 bit processes) | |
| PROCESSOR_IDENTIFIER | Y | Processor ID of the user’s workstation. |
| PROCESSOR_LEVEL | Y | Processor level of the user’s workstation. |
| PROCESSOR_REVISION | Y | Processor version of the user’s workstation. |
| ProgramW6432 | =%ProgramFiles%(but only available when running under a 64 bit OS) | |
| ProgramData | C:\ProgramData | |
| ProgramFiles | C:\Program Files or C:\Program Files (x86) | |
| ProgramFiles(x86) 1 | C:\Program Files (x86) (but only available when running under a 64 bit OS) | |
| PROMPT | Code for current command prompt format,usually $P$G C:> | |
| PSModulePath | %SystemRoot%\system32\WindowsPowerShell\v1.0\Modules\ | |
| Public | C:\Users\Public | |
| RANDOM | Y | A random integer number, anything from 0 to 32,767 (inclusive). |
| %SessionName% | Terminal servers only – for a terminal server session, SessionName is a combination of the connection name, followed by #SessionNumber. For a console session, SessionName returns “Console”. | |
| SYSTEMDRIVE | C: | |
| SYSTEMROOT | By default, Windows is installed to C:\Windows but there’s no guarantee of that, Windows can be installed to a different folder, or a different drive letter. systemroot is a read-only system variable that will resolve to the correct location. Defaults in early Windows versions are C:\WINNT, C:\WINNT35 and C:\WTSRV | |
| TEMP and TMP | User Variable | C:\Users\{Username}\AppData\Local\Temp Under XP this was \{username}\Local Settings\Temp |
| TIME | Y | The current time using same format as TIME. |
| UserDnsDomain | Y User Variable | Set if a user is a logged on to a domain and returns the fully qualified DNS domain that the currently logged on user’s account belongs to. |
| USERDOMAIN | {userdomain} | |
| USERDOMAIN_roamingprofile | The user domain for RDS or standard roaming profile paths. Windows 8/10/2012 (or Windows 7/2008 with Q2664408) | |
| USERNAME | {username} | |
| USERPROFILE | %SystemDrive%\Users\{username} This is equivalent to the $HOME environment variable in Unix/Linux | |
| WINDIR | %windir% is a regular User variable and can be changed, which makes it less robust than %SystemRoot% Set by default as windir=%SystemRoot% %WinDir% pre-dates Windows NT, its use in many places has been replaced by the system variable: %SystemRoot% |
1 Only on 64 bit systems, is used to store 32 bit programs.
Unless stated otherwise, all the variables above are System variables
Environment variables are stored in the registry:
User Variables: HKEY_CURRENT_USER\Environment
System Variables: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment
By default, files stored under Local Settings do not roam with a roaming profile.
Dynamic environment variables are read-only and are computed each time the variable is expanded. When all variables are listed with SET, these will not appear in the list. Do not attempt to directly SET a dynamic variable.
Shell variables
Variables for current shell session are created with the SET command and are available only to the current CMD shell. These are only stored in memory not the registry. Shell variables are destroyed when the current shell (CMD) exits.
Running the SET command with no options will display all shell variables but also all User and System environment variables.
If the SET command is used to modify the PATH, or if it is removed completely with PATH ; that will not affect any other programs or CMD sessions opened before or after the current one.