After i quit GDB every user-defined function disappear. Im sure there should be some way to make it available between sessions.
GDB reads the following files before starting:
It is a common practice to edit e.g.
~/.gdbinit to define the user-defined function using an external editor and use
source ~/.gdbinit in a GDB session to reload that file. Once the function works as you expect, just leave it in your
~/.gdbinit and it will be available in all future GDB sessions.