Linker

Linker is a compiler component that is used to combine several object code files from various sources into one executable file. Its main purpose is to resolve references between the files (symbol resolution) and perform relocation for memory segments, so that all the data in the program is correctly linked together.

Linkers are used on many platforms, but are especially prevalent in the context of personal computers (PCs). They are often used in the development process for applications, and serve to organize a large amount of code into a smaller, more compact file.

Linkers are usually part of a compiler package, and can also be used to link together libraries, both from the development environment (static linking) and perhaps from other libraries (dynamic linking).

The main stages of a link edit are:

1. Library search – Searching through the list of libraries to locate the necessary code.

2. Symbol resolution – Resolving the references between objects and their implementation.

3. Object code joining – Combining the object programs into one executable program.

4. Address relocation – Adjusting references in the code, in case the loaded segments are not located in the same memory addresses as indicated in the code.

5. Debugging information – Generating debugging information to allow for easier debugging.

Linkers can also perform tasks such as running additional scripts to perform additional configuration, adding security checks to the application and ensuring compatibility with other platforms.

Computer viruses have also been created for malicious use, specifically to infect and link malicious code into existing programs. Therefore one of the most important tasks for a linker is to ensure safety and security of the linked program.