For the people that watched the Licences & Vulnerabilities Tech Tips where I talked about linking vs static compiling in the context of GPL…
When you want to make use of functions in a library within your code you have options:

So, I have a library, `foo.c` with some functions that I want to use in my application, `bar`
1. Use the library _statically_ – that means the functions in the library are going to be part of your binary
– Compile the library
`gcc -c -o foo.o foo.c`
– Then make it a static library
`ar rcs libfoo.a foo.o`
– Now use it in your code
`gcc -c bar.c -o bar.o`
`gcc -o bar bar.o -L. -lfoo`

You have a single binary that includes both your code and the library’s code.
This is classed as a _derivative work_ so if the library was LGPL or GPL, then your code must also be GPL

2. Use the library as a _shared object_
This means that the library code has been compiled with a `-shared` flag and you end up with a `.so` file – e.g. `libfoo.so`
In _your_ code you can then link to that library
`gcc -L. -lfoo -o bar bar.c`

In this instance, the original library is untouched and your code is just making use of it. As long as the library ls licensed under **LGPL**, then your code can be commercial.

That is a highly simplified answer – I may do a blog post about it where I can use more space.

For those of you who didn’t watch the tech tips… Go watch it on the replay!