01-27-2004
Note that processes do not have a limit of 20 file descriptors
as suggested in your mail - rather the limit is OPEN_MAX.
Here is the formal POSIX definition of a file descriptor:
A per-process unique, non-negative integer used to identify an open file for the purpose of file access. The value of a file descriptor is from zero to OPEN_MAX. A process can have no more than OPEN_MAX file descriptors open simultaneously.
Note also the difference between file DESCRIPTOR and file DESCRIPTION. From SUSv3 ....
(Open) File Description
A record of how a process or group of processes is accessing a file. Each file descriptor refers to exactly one open file description, but an open file description can be referred to by more than one file descriptor. The file offset, file status, and file access modes are attributes of an open file description.
- Finnbarr
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LEARN ABOUT HPUX
sem_destroy
sem_destroy(2) System Calls Manual sem_destroy(2)
NAME
sem_destroy - destroy an unnamed POSIX semaphore
SYNOPSIS
DESCRIPTION
is used to destroy an unnamed semaphore. A successful call to will invalidate the unnamed semaphore referred to by sem and removes all
descriptors referencing it. The semaphore should have been created by a previous call to and there should not be any processes blocked on
it.
To use this function, link in the realtime library by specifying on the compiler or linker command line.
EXAMPLES
The following call to will destroy an unnamed semaphore referred to by sem and remove all descriptors referencing it.
RETURN VALUE
If the semaphore was destroyed and the descriptors referencing it were removed, returns 0 to the caller.
If the semaphore could not be destroyed, the call returns -1 and sets to indicate the error.
ERRORS
fails and does not perform the requested operation if any of the following conditions are encountered:
[EBUSY] There are threads currently blocked on the semaphore or there are outstanding locks held on the semaphore.
[EINVAL] The argument sem is not a valid unnamed semaphore.
SEE ALSO
sem_init(2), sem_open(2), <semaphore.h>.
STANDARDS CONFORMANCE
sem_destroy(2)