def-specify-module-definition-file.md

description	Learn more about: /DEF (Specify module-definition file)
title	/DEF (Specify module-definition file)
ms.date	03/27/2025
f1_keywords	VC.Project.VCLinkerTool.ModuleDefinitionFile /def
helpviewer_keywords	module definition files, specifying DEF linker option -DEF linker option module definition files /DEF linker option

/DEF (Specify module-definition file)

Specifies a module-definition file to the linker.

Syntax

/DEF:filename

Arguments

filename
The name of a module-definition file (.def) to be passed to the linker. When expanded, the fully qualified filename must not exceed MAX_PATH (260 characters).

Remarks

The /DEF linker option passes a module-definition file (.def) to the linker. Only one .def file can be specified to LINK. For details about .def files, see Module-definition files.

To specify a .def file from within the development environment, add it to the project along with your other source files and then specify the file in the project's Property Pages dialog.

To set this linker option in the Visual Studio development environment

1. Open the project's Property Pages dialog box. For more information, see Set compiler and build properties.
2. Select the Configuration Properties > Linker > Input property page.
3. Modify the Module Definition File property. Choose OK or Apply to save your changes.

To set this linker option programmatically

• See xref:Microsoft.VisualStudio.VCProjectEngine.VCLinkerTool.ModuleDefinitionFile%2A.

See also

MSVC linker reference
MSVC Linker Options