Is it safe to recompile an executable while it's running?

Question

What happens if I recompile an executable while it\'s running? Does the operating system read all of the executable\'s contents into memory when it starts running it, so it

Answer 1

It depends.

If the OS read the whole of the executable into memory and doesn't refer back to the disk image then yes you can recompile it while it was "in use".

In practice this doesn't always happen. If the OS keeps a file handle open (like Windows does) on the executable this will prevent the file being deleted and/or overwritten.

With Linux/Unix it is possible to overwrite a file that's "in use". See David Thornley's answer for a detailed explanation.