11.1.1 BEGIN Probe

The BEGIN probe fires before any other probe. No other probe fires until all BEGIN clauses have completed. This probe can be used to initialize any state that is needed in other probes. The following example shows how to use the BEGIN probe to initialize an associative array to map between mmap() protection bits and a textual representation:

  prot[0] = "---";
  prot[1] = "r--";
  prot[2] = "-w-";
  prot[3] = "rw-";
  prot[4] = "--x";
  prot[5] = "r-x";
  prot[6] = "-wx";
  prot[7] = "rwx";

  printf("mmap with prot = %s", prot[arg2 & 0x7]);

The BEGIN probe fires in an unspecified context, which means the output of stack or ustack, and the value of context-specific variables such as execname, are all arbitrary. These values should not be relied upon or interpreted to infer any meaningful information. No arguments are defined for the BEGIN probe.