How do you run system commands like loading a db over a handle

I've connected to a process and I want to load a db into it from another process. How do you do this in kdb+ as you can't use system"" because it clashes with handle""

You need to escape the quotation marks

h"system\"p\""

But better to use a list (edit: I had parse tree which is wrong as pointed out by Igor) when sending queries over IPC. One of the reasons for that is exactly the issue you run into.

h:hopen 9999                                                                                           
h"system\"p\""                                                                                          q)
9999i                                                                                                   
h(system;"p")                                                                                           
9999i                                                                                                   
q)    

You can read about parse trees here https://code.kx.com/q/basics/parsetrees/ and here https://www.defconq.tech/docs/concepts/functionalSelect