4.2 Variables
All variables are global and can be used in Sections or Functions. Note that by default, variables are limited to 1024 characters. To extend this limit, build NSIS with a bigger value of the NSIS_MAX_STRLEN build setting or use the special build.
4.2.1 User Variables
$VARNAME
User variables must be declared with the Var command. You can use these variables to store values, work with string manipulation etc.
4.2.1.1 Var
[/GLOBAL] var_name
Declare a user variable. Allowed characters for variables names: [a-z][A-Z][0-9] and '_'. All defined variables are global, even if defined in a section or a function. To make this clear, variables defined in a section or a function must use the /GLOBAL flag. The /GLOBAL flag is not required outside of sections and functions.
Var example Function testVar Var /GLOBAL example2 StrCpy $example "example value" StrCpy $example2 "another example value" FunctionEnd
4.2.2 Other Writable Variables
$0, $1, $2, $3, $4, $5, $6, $7, $8, $9, $R0, $R1, $R2, $R3, $R4, $R5, $R6, $R7, $R8, $R9
Registers. These variables can be used just like user variables, but are usually used in shared functions or macros. You don't have to declare these variables so you won't get any name conflicts when using them in shared code. When using these variables in shared code it's recommended that you use the stack to save and restore their original values. These variables can also be used for communication with plug-ins because they can be read and written by the plug-in DLLs.
$INSTDIR
The installation directory ($INSTDIR is modifiable using StrCpy, ReadRegStr, ReadINIStr, etc. - This could be used, for example, in the .onInit function to do a more advanced detection of install location).
Note that in uninstaller code, $INSTDIR contains the directory where the uninstaller lies. It does not necessarily contain the same value it contained in the installer. For example, if you write the uninstaller to $WINDIR and the user doesn't move it, $INSTDIR will be $WINDIR in the uninstaller. If you write the uninstaller to another location, you should keep the installer's $INSTDIR in the registry or an alternative storing facility and read it in the uninstaller.
$OUTDIR
The current output directory (set implicitly via SetOutPath or explicitly via StrCpy, ReadRegStr, ReadINIStr, etc)
$CMDLINE
The command line of the installer. The format of the command line can be one of the following:
- "full\path to\installer.exe" PARAMETER PARAMETER PARAMETER
- installer.exe PARAMETER PARAMETER PARAMETER
- For parsing out the PARAMETER portion, see GetParameters. If /D= is specified on the command line (to override the install directory) it won't show up in $CMDLINE.
$LANGUAGE
The identifier of the language that is currently used. For example, English is 1033. You can only change this variable in .onInit.
4.2.3 Constants
Constants can also be used in the InstallDir attribute.
Note that some of the new constants will not work on every OS. For example, $CDBURN_AREA will only work on Windows XP and above. If it's used on Windows 98, it'll be empty. Unless mentioned otherwise, a constant should be available on every OS.
$PROGRAMFILES, $PROGRAMFILES32, $PROGRAMFILES64
The program files directory (usually C:\Program Files but detected at runtime). On Windows x64, $PROGRAMFILES and $PROGRAMFILES32 point to C:\Program Files (x86) while $PROGRAMFILES64 points to C:\Program Files. Use $PROGRAMFILES64 when installing x64 applications.
$COMMONFILES, $COMMONFILES32, $COMMONFILES64
The common files directory. This is a directory for components that are shared across applications (usually C:\Program Files\Common Files but detected at runtime). On Windows x64, $COMMONFILES and $COMMONFILES32 point to C:\Program Files (x86)\Common Files while $COMMONFILES64 points to C:\Program Files\Common Files. Use $COMMONFILES64 when installing x64 applications.
$DESKTOP
The Windows desktop directory. The context of this constant (All Users or Current user) depends on the SetShellVarContext setting. The default is the current user.
$EXEDIR
The directory containing the installer executable (technically this is a variable and you can modify it, but it is probably not a good idea).
$EXEFILE
The base name of the installer executable.
$EXEPATH
The full path of the installer executable.
${NSISDIR}
A symbol that contains the path where NSIS is installed. Useful if you want to reference resources that are in NSIS directory e.g. Icons, UIs etc.
When compiled with support for keeping makensis and the data in the same place (the default on Windows), it is in the same place as makensis, on other platforms it is set at compile time (See the INSTALL file for info). In both instances you can modify it at runtime by setting the NSISDIR environment variable. See section 3.1.3 for more info.
$WINDIR
The Windows directory (usually C:\Windows or C:\WinNT but detected at runtime).
$SYSDIR
The Windows system directory (usually C:\Windows\System or C:\WinNT\System32 but detected at runtime).
$TEMP
The temporary directory.
$STARTMENU
The start menu folder (useful for adding start menu items using CreateShortcut). The context of this constant (All Users or Current user) depends on the SetShellVarContext setting. The default is the current user.
$SMPROGRAMS
The start menu programs folder (use this whenever you want $STARTMENU\Programs). The context of this constant (All Users or Current user) depends on the SetShellVarContext setting. The default is the current user.
$SMSTARTUP
The start menu programs / startup folder. The context of this constant (All Users or Current user) depends on the SetShellVarContext setting. The default is the current user.
$QUICKLAUNCH
The quick launch folder for IE4 active desktop and above. If quick launch is not available it simply returns the same as $TEMP.
$DOCUMENTS
The documents directory. A typical path for the current user is C:\Documents and Settings\Foo\My Documents. The context of this constant (All Users or Current user) depends on the SetShellVarContext setting. The default is the current user.
This constant is not available on Windows 95 unless Internet Explorer 4 is installed.
$SENDTO
The directory that contains Send To menu shortcut items.
$RECENT
The directory that contains shortcuts to the user's recently used documents.
$FAVORITES
The directory that contains shortcuts to the user's favorite websites, documents, etc. The context of this constant (All Users or Current user) depends on the SetShellVarContext setting. The default is the current user.
This constant is not available on Windows 95 unless Internet Explorer 4 is installed.
$MUSIC
The user's music files directory. The context of this constant (All Users or Current user) depends on the SetShellVarContext setting. The default is the current user.
This constant is available on Windows XP, ME and above.
$PICTURES
The user's picture files directory. The context of this constant (All Users or Current user) depends on the SetShellVarContext setting. The default is the current user.
This constant is available on Windows 2000, XP, ME and above.
$VIDEOS
The user's video files directory. The context of this constant (All Users or Current user) depends on the SetShellVarContext setting. The default is the current user.
This constant is available on Windows XP, ME and above.
$NETHOOD
The directory that contains link objects that may exist in the My Network Places/Network Neighborhood folder.
This constant is not available on Windows 95 unless Internet Explorer 4 with Active Desktop is installed.
$FONTS
The system's fonts directory.
$TEMPLATES
The document templates directory. The context of this constant (All Users or Current user) depends on the SetShellVarContext setting. The default is the current user.
$APPDATA
The application data directory. Detection of the current user path requires Internet Explorer 4 and above. Detection of the all users path requires Internet Explorer 5 and above. The context of this constant (All Users or Current user) depends on the SetShellVarContext setting. The default is the current user.
This constant is not available on Windows 95 unless Internet Explorer 4 with Active Desktop is installed.
$LOCALAPPDATA
The local (non-roaming) application data directory.
This constant is available on Windows 2000 and above.
$PRINTHOOD
The directory that contains link objects that may exist in the Printers folder.
This constant is not available on Windows 95 and Windows 98.
$INTERNET_CACHE
Internet Explorer's temporary internet files directory.
This constant is not available on Windows 95 nor Windows NT 4 unless Internet Explorer 4 with Active Desktop is installed.
$COOKIES
Internet Explorer's cookies directory.
This constant is not available on Windows 95 nor Windows NT 4 unless Internet Explorer 4 with Active Desktop is installed.
$HISTORY
Internet Explorer's history directory.
This constant is not available on Windows 95 nor Windows NT 4 unless Internet Explorer 4 with Active Desktop is installed.
$PROFILE
The user's profile directory. A typical path is C:\Documents and Settings\Foo.
This constant is available on Windows 2000 and above.
$ADMINTOOLS
A directory where administrative tools are kept. The context of this constant (All Users or Current user) depends on the SetShellVarContext setting. The default is the current user.
This constant is available on Windows 2000, ME and above.
$RESOURCES
The resources directory that stores themes and other Windows resources (usually $WINDIR\Resources but detected at runtime).
This constant is available on Windows XP and above.
$RESOURCES_LOCALIZED
The localized resources directory that stores themes and other Windows resources (usually $WINDIR\Resources\1033 but detected at runtime).
This constant is available on Windows XP and above.
$CDBURN_AREA
A directory where files awaiting to be burned to CD are stored.
This constant is available on Windows XP and above.
$HWNDPARENT
HWND of the main window (in decimal).
$PLUGINSDIR
The path to a temporary folder created upon the first usage of a plug-in or a call to InitPluginsDir. This folder is automatically deleted when the installer exits. This makes this folder the ideal folder to hold INI files for InstallOptions, bitmaps for the splash plug-in, or any other file that a plug-in needs to work.
4.2.4 Constants Used in Strings
$$
Use to represent $.
$\r
Use to represent a carriage return (\r).
$\n
Use to represent a newline (\n).
$\t
Use to represent a tab (\t).