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GNO Snooper CDA

The GNO Snooper CDA is a utility that is very helpful in debugging software, and reporting system crashes. Snooper has access to information inside the kernel that is not generally available to processes.

When you enter the control panel and choose ``GNO Snooper'' a process list is displayed, which is very similar to the ps(1) shell command, and a menu is presented with the following options, each of which is invoked by typing it's first letter:

D)etails

Get detailed information on a process. Snooper asks you for the process ID number of the process you want to investigate. Snooper then dumps the state of the 65816 registers and shows various other information about the process.

K)ill

This option sends a SIGKILL to a process. Just type in the process ID of the process you want to kill.

P)rocess Group Dump

Dumps the system process group tables, which is very useful for debugging code which manipulates process groups. The first table, ``pgrp'', is the process group reference count table. This table lists how many processes (and TTYs) belong to that process group. Process group ids start at 2, so the first pgrp listed is 2.

The second listing is the ttyStruct table. This table shows to which process group each TTY belongs. The TTYs start with .null (0), then move on to .ttyb, .ttya, .ttyco, etc.

F)ile Table Dump

Lists all open files known to GNO. The information is presented in tuples. The first element is the real GS/OS refNum or device driver ID. The second is the type of file (GSOS, ttyXX, or PIPE). The third is how many references to that file are open. This information is global, so if two processes have .NULL opened, the refcount for .tty00 will be 2.


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