[bpftrace] Nothing happens

Maybe I do not fully understood how to bpftrace/eBPF works, but this bpftrace script do not work (it seems):

bpftrace -e 'tracepoint:syscalls:sys_enter_open* { printf("A"); }'

When opening file by cat under bash, nothing happens.

No asterisk after the _open? Do the One-Liners here help? https://github.com/iovisor/bpftrace

On openSUSE Leap 15.4 doing:

localhost:/mnt # bpftrace -e 'BEGIN { printf("A"); }'
Attaching 1 probe...

do not print A.

Ok. It works as terminal. I forgot
escape character. Now BEGIN worked.