Start bitcoind in a screen in a debugger

run.gdbscript

set disable-randomization off
set $_exitcode = -999
set height 0
handle SIGTERM nostop print pass
handle SIGPIPE nostop
define hook-stop
    if $_exitcode != -999
        quit
    else
        shell echo | mail -s "NOTICE: app has stopped on unhandled signal" root
    end
end
echo .gdbinit: running app\n
run

start.sh

#!/bin/bash
# Start bitcoind in a screen in a debugger
# This works like -daemon, except that it is possible to jump into the debugger at any time
# by attaching to the screen (screen -r). On a crash the debugger will keep running,
# on a normal exit it will quit automatically.
screen -d -m gdb -x run.gdbscript -args ./bitcoind -datadir=/usb/bitcoin

Important: don't forget set disable-randomization off in the gdb script. By default, GDB disables ASLR, which reduces hardening against various forms of exploitation. This is not a good idea for network software such as bitcoin core, so be sure to turn off that "feature".