hangs.py

import r2pipe

r = r2pipe.open()

r.cmd('ood')
r.cmd('dcu @main')

last_pointer = '1'
while True:
    poiner_from_stack = str(r.cmdj('pxqj 8 @rsp')[0])
    if last_pointer!=poiner_from_stack:
        # will never stop when run as r2 /bin/ls
        print(poiner_from_stack)
        break
    r.cmd('ds')
    # why ds does not change pxqj?

works_good.py

import r2pipe

# when used with '/bin/ls' it does not loop forever
r = r2pipe.open('/bin/ls')

r.cmd('ood')
r.cmd('dcu @main')

last_pointer = '1'
while True:
    poiner_from_stack = str(r.cmdj('pxqj 8 @rsp')[0])
    if last_pointer!=poiner_from_stack:
        print(poiner_from_stack)
        break
    r.cmd('ds')