Load symbols from file (mess):

> file mess
Reading symbols from mess...done.
> target exec mess
> b main
> r

Renesas simulator:

> file rx52n.elf
> target sim
> load
> b main
> r

Script from file:

gdb -x mess.gdb

Script from file (CLI):

> source mess_gdb.py

Python API for scripts (https://sourceware.org/gdb/onlinedocs/gdb/Python-API.html#Python-API)

Pause running process:

> [CTRL+C]

TUI:

> [CTRL+x+a]
> layout asm

Print:

> p/x $x30 - hex
> p/t $x30 - binary
> p/d $x30 - decimal
> display/x $x30 - print after each gdb stop
> i r x30