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Full Discussion: Problem with semaphores
Top Forums Programming Problem with semaphores Post 302448907 by Corona688 on Friday 27th of August 2010 11:12:53 AM
Old 08-27-2010
You can tell what line the segmentation fault occurs on by compiling with -ggdb, then running with gdb. i.e.

Code:
gdb
run ./filename
(text informing you the program crashed)
bt f

 

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IPCS(1) 						    BSD General Commands Manual 						   IPCS(1)

NAME
ipcs -- report System V interprocess communication facilities status SYNOPSIS
ipcs [-abcmopqstMQST] [-C system] [-N core] DESCRIPTION
The ipcs program provides information on System V interprocess communication (IPC) facilities on the system. The options are as follows: -a Show the maximum amount of information possible when displaying active semaphores, message queues, and shared memory segments. (This is shorthand for specifying the -b, -c, -o, -p, and -t options.) -b Show the maximum allowed sizes for active semaphores, message queues, and shared memory segments. The ``maximum allowed size'' is the maximum number of bytes in a message on a message queue, the size of a shared memory segment, or the number of semaphores in a set of semaphores. -c Show the creator's name and group for active semaphores, message queues, and shared memory segments. -m Display information about active shared memory segments. -o Show outstanding usage for active message queues, and shared memory segments. The ``outstanding usage'' is the number of messages in a message queue, or the number of processes attached to a shared memory segment. -p Show the process ID information for active semaphores, message queues, and shared memory segments. The ``process ID information'' is the last process to send a message to or receive a message from a message queue, the process that created a semaphore, or the last process to attach or detach a shared memory segment. -q Display information about active message queues. -s Display information about active semaphores. -t Show access times for active semaphores, message queues, and shared memory segments. The access times is the time of the last con- trol operation on an IPC object, the last send or receive of a message, the last attach or detach of a shared memory segment, or the last operation on a semaphore. -C system Extract the name list from the specified system instead of the default ``/netbsd''. -M Display system information about shared memory. -N core Extract values associated with the name list from the specified core instead of the default ``/dev/kmem''. and semaphores. -Q Display system information about messages queues. -S Display system information about semaphores. -T Display system information about shared memory, message queues and semaphores. (This is shorthand for specifying the -M, -Q, and -S options.) If none of the -M, -m, -Q, -q, -S, -s, or -T options are specified, information about all active IPC facilities is listed. RESTRICTIONS
System data structures may change while ipcs is running; the output of ipcs is not guaranteed to be consistent. FILES
/dev/kmem default kernel memory /netbsd default system name list SEE ALSO
ipcrm(1), shmat(2), shmctl(2), shmdt(2), shmget(2) AUTHORS
Thorsten Lockert <tholo@sigmasoft.com> BUGS
This manual page is woefully incomplete, because it does not at all attempt to explain the information printed by ipcs. BSD
March 21, 2004 BSD
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