(gdb) gcore
warning: target file /proc/21937/cmdline contained unexpected null characters
warning: Memory read failed for corefile section, 1048576 bytes at 0x7f62505b7000.
warning: Memory read failed for corefile section, 1048576 bytes at 0x7f6250f41000.
warning: Memory read failed for corefile section, 1048576 bytes at 0x7f625114b000.
Saved corefile core.21937