Gacutil.exe (Global Assembly Cache Tool)

The Global Assembly Cache tool allows you to view and manipulate the contents of the global assembly cache and download cache.

The Global Assembly Cache tool is automatically installed with Visual Studio. To start the tool, use the Visual Studio Command Prompt. At the command prompt, type the following:

gacutil [options] [assemblyName | assemblyPath | assemblyListFile]

Parameters

Option	Description
/cdl	Deletes the contents of the download cache.
/f	Specify this option with the /i or /il options to force an assembly to reinstall. If an assembly with the same name already exists in the global assembly cache, the tool overwrites it.
/h[elp]	Displays command syntax and options for the tool.
/i assemblyPath	Installs an assembly into the global assembly cache.
/if assemblyPath	Installs an assembly into the global assembly cache. If an assembly with the same name already exists in the global assembly cache, the tool overwrites it. Specifying this option is equivalent to specifying the /i and /f options together.
/il assemblyListFile	Installs one or more assemblies specified in assemblyListFile into the global assembly cache.
/ir assemblyPath scheme id description	Installs an assembly into the global assembly cache and adds a reference to count the assembly. You must specify the assemblyPath, scheme, id,and description parameters with this option. For a description of the valid values you can specify for these parameters, see the /r option. Specifying this option is equivalent to specifying the /i and /r options together.
/l [assemblyName]	Lists the contents of the global assembly cache. If you specify the assemblyName parameter, the tool lists only the assemblies matching that name.
/ldl	Lists the contents of the downloaded files cache.
/lr [assemblyName]	Lists all assemblies and their corresponding reference counts. If you specify the assemblyName parameter, the tool lists only the assemblies matching that name and their corresponding reference counts.
/nologo	Suppresses the Microsoft startup banner display.
/r [assemblyName | assemblyPath] scheme id description	Specifies a traced reference to an assembly or assemblies to install or uninstall. Specify this option with the /i, /il, /u, or /ul options. To install an assembly, specify the assemblyPath, scheme, id,and description parameters with this option. To uninstall an assembly, specify the assemblyName, scheme, id,and description parameters. To remove a reference to an assembly, you must specify the same scheme, id, and description parameters that were specified with the /i and /r (or /ir) options when the assembly was installed. If you are uninstalling an assembly, the tool also removes the assembly from the global assembly cache if it is the last reference to remove and if Windows Installer has no outstanding references to the assembly. The scheme parameter specifies the type of installation scheme. You can specify one of the following values: UNINSTALL_KEY: Specify this value if the installer adds the application to Add/Remove Programs in Microsoft Windows. Applications add themselves to Add/Remove Programs by adding a registry key to HKLM\Software\Microsoft\Windows\CurrentVersion. FILEPATH: Specify this value if the installer does not add the application to Add/Remove Programs. OPAQUE: Specify this value if supplying a registry key or file path does not apply to your installation scenario. This value allows you to specify custom information for the id parameter. The value to specify for the id parameter depends on the value specified for the scheme parameter: If you specify UNINSTALL_KEY for the scheme parameter, specify the name of the application set in the HKLM\Software\Microsoft\Windows\CurrentVersion registry key. For example, if the registry key is HKLM\Software\Microsoft\Windows\CurrentVersion\MyApp, specify MyApp for the id parameter. If you specify FILEPATH for the scheme parameter, specify the full path to the executable file that installs the assembly as the id parameter. If you specify OPAQUE for the scheme parameter, you can supply any piece of data as the id parameter. The data you specify must be enclosed in quotation marks (""). The description parameter allows you to specify descriptive text about the application to install. This information is displayed when references are enumerated.
/silent	Suppresses the display of all output.
/u assemblyName	Uninstalls an assembly from the global assembly cache.
/uf assemblyName	Forces a specified assembly to uninstall by removing all references to the assembly. Specifying this option is equivalent to specifying the /u and /f options together. Note You cannot use this option to remove an assembly that was installed using Microsoft Windows Installer. If you attempt this operation, the tool displays an error message.
/ul assemblyListFile	Uninstalls one or more assemblies specified in assemblyListFile from the global assembly cache.
/u[ngen] assemblyName	Uninstalls a specified assembly from the global assembly cache. If the specified assembly has existing reference counts, the tool displays the reference counts and does not remove the assembly from the global assembly cache. Note In the .NET Framework version 2.0, /ungen is not supported. Instead, use the uninstall command of the Ngen.exe (Native Image Generator). In the .NET Framework versions 1.0 and 1.1, specifying /ungen causes Gacutil.exe to remove the assembly from the native image cache. This cache stores the native images for assemblies that have been created using the Ngen.exe (Native Image Generator).
/ur assemblyName scheme id description	Uninstalls a reference to a specified assembly from the global assembly cache. To remove a reference to an assembly, you must specify the same scheme, id, and description parameters that were specified with the /i and /r (or /ir) options when the assembly was installed. For a description of the valid values you can specify for these parameters, see the /r option. Specifying this option is equivalent to specifying the /u and /r options together.
/?	Displays command syntax and options for the tool.

Remarks

This tool provides much of the same functionality for viewing the cache as the Windows Shell Extension (Shfusion.dll), but is more usable from build scripts, makefiles, and batch files.

Note
You must have administrator privileges to use Gacutil.exe.

Specifically, Gacutil.exe allows you to install assemblies into the cache, remove them from the cache, and list the contents of the cache.

Gacutil.exe provides options that support reference counting similar to the reference counting scheme supported by Windows Installer. You can use Gacutil.exe to install two applications that install the same assembly; the tool keeps track of the number of references to the assembly. As a result, the assembly will remain on the computer until both applications are uninstalled. If you are using Gacutil.exe for actual product installations, use the options that support reference counting. Use the /i and /r options together to install an assembly and add a reference to count it. Use the /u and /r options together to remove a reference count for an assembly. Be aware that using the /i and /u options alone does not support reference counting. These options are appropriate for use during product development but not for actual product installations.

Use the /il or /ul options to install or uninstall a list of assemblies stored in an ANSI text file. The contents of the text file must be formatted correctly. To use a text file to install assemblies, specify the path to each assembly on a separate line in the file. The following example demonstrates the contents of a file containing assemblies to install.

myAssembly1.dll
myAssembly2.dll
myAssembly3.dll

To use a text file to uninstall assemblies, specify the fully qualified assembly name for each assembly on a separate line in the file. The following example demonstrates the contents of a file containing assemblies to uninstall.

myAssembly1,Version=1.1.0.0,Culture=en,PublicKeyToken=874e23ab874e23ab
myAssembly2,Version=1.1.0.0,Culture=en,PublicKeyToken=874e23ab874e23ab
myAssembly3,Version=1.1.0.0,Culture=en,PublicKeyToken=874e23ab874e23ab

Examples

The following command installs the assembly mydll.dll into the global assembly cache.

gacutil /i mydll.dll

The following command removes the assembly hello from the global assembly cache as long as no reference counts exist for the assembly.

gacutil /u hello

Note that the previous command might remove more than one assembly from the assembly cache because the assembly name is not fully specified. For example, if both version 1.0.0.0 and 3.2.2.1 of hello are installed in the cache, the command gacutil /u hello removes both of the assemblies.

Use the following example to avoid removing more than one assembly. This command removes only the hello assembly that matches the fully specified version number, culture, and public key.

gacutil /u hello, Version=1.0.0.1, Culture="de",PublicKeyToken=45e343aae32233ca

The following command installs the assemblies specified in the file assemblyList.txt into the global assembly cache.

gacutil /il assemblyList.txt

The following command removes the assemblies specified in the file assemblyList.txt from the global assembly cache.

gacutil /ul assemblyList.txt

The following command installs myDll.dll into the global assembly cache and adds a reference to count it. The assembly myDll.dll is used by the application MyApp. The UNINSTALL_KEY MyApp parameter specifies the registry key that adds MyApp to Add/Remove Programs in Windows. The description parameter is specified as My Application Description.

gacutil /i /r myDll.dll UNINSTALL_KEY MyApp "My Application Description"

The following command installs myDll.dll into the global assembly cache and adds a reference to count it. The scheme parameter, FILEPATH, and the id parameter, c:\applications\myApp\myApp.exe, specify the path to the application that is installing myDll.dll. The description parameter is specified as MyApp.

gacutil /i /r myDll.dll FILEPATH c:\applications\myApp\myApp.exe MyApp

The following command installs myDll.dll into the global assembly cache and adds a reference to count it. The scheme parameter, OPAQUE, allows you to customize the id and description parameters.

gacutil /i /r mydll.dll OPAQUE "Insert custom application details here" "Insert Custom description information here"

The following command removes the reference to myDll.dll by the application myApp. If this is the last reference to the assembly, it will also remove the assembly from the global assembly cache.

gacutil /u /r myDll.dll FILEPATH c:\applications\myApp\myApp.exe MyApp

The following command lists the contents of the global assembly cache.

gacutil /l

See Also

Reference

Shfusion.dll (Assembly Cache Viewer)

Regasm.exe (Assembly Registration Tool)

Visual Studio Command Prompt

Concepts

Global Assembly Cache

Other Resources

.NET Framework Tools