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1. UNIX for Beginners Questions & Answers
I was asked to add this piece of code to a c program which I will execute through the shell:
for(long i = 0; i < NITER; i++)
{ sem_wait( &sema);
count++;
sem_post( &sema); }
I didn't get it, which is the critical section ? if it's "count++" how would a thread wake up in order to enter it... (1 Reply)
Discussion started by: uniran
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Can anyone tell me abt the Semaphore concept and what is semaphore???
is semaphore id is associated in terms as in resources like semaphore id 1 indicates cpu share unit is given and semaphore id 2 will indicate abt the memore or semaphore id 3 will tell us the i/o components (1 Reply)
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3. Shell Programming and Scripting
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In my server code there is a thread per client...
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what is semaphore? can any body explain it in a more simple way than the manual ??
replies appreciated
Regards
raguram R (7 Replies)
Discussion started by: raguramtgr
7 Replies
6. Shell Programming and Scripting
Hi,
I am looking to use a semaphore for the first time in one of my scripts. I am just wondering if there are any simple examples or tutorials around?
I am a beginner so the simpler the better :)
Thanks
-Jaken (2 Replies)
Discussion started by: Jaken
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7. UNIX for Advanced & Expert Users
Hi All,
I am going through the semaphore concept and have a doubt regarding the same and hope to get a resolution here.
I have a file which has a number of records.
I want to write an application (in C) which will be able to do concurrent read/write on these records.
Of what I have... (8 Replies)
Discussion started by: maverix
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8. Programming
I'm running one multithreaded application, in that one of my thread
is waiting infinitely in a semphore. Is there a way to determine, in
which semaphore the particular thread is waiting and which thread(s)
is holding the semaphore. (5 Replies)
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9. UNIX for Dummies Questions & Answers
Hi,
I'm new to UNIX.
I need to know what's a semaphore
Do reply.
Thanks
VJ (3 Replies)
Discussion started by: vjsony
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10. UNIX for Dummies Questions & Answers
hi, is there any command where we can monitor semaphores? (1 Reply)
Discussion started by: yls177
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sem_unlink(2) System Calls Manual sem_unlink(2)
NAME
sem_unlink - unlink a named POSIX semaphore
SYNOPSIS
DESCRIPTION
is used to unlink named semaphores. A successful call to marks the semaphore, specified by name, for removal. Calling does not affect
processes, including the calling process, which currently have a descriptor, obtained from a call to Named semaphores are uniquely identi-
fied by character strings. All character string names will be pre-processed to ensure variations of a pathname resolve to the same sema-
phore name. If the semaphore is successfully marked for removal by a call to the semaphore will be removed when all processes remove their
descriptors to the specified semaphore by calling Subsequent calls to using the string name will refer to a new semaphore.
To use this function, link in the realtime library by specifying on the compiler or linker command line.
EXAMPLES
The following call to will remove the named semaphore named by the string name. If the semaphore is currently referenced by one or more
processes, the semaphore will be marked for removal and removed when there are no more processes referencing it.
RETURN VALUE
If the semaphore was unlinked successfully, returns 0.
If the semaphore could not be unlinked, 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:
[EACCES] The named semaphore exists and the process does not have the permissions to unlink the semaphore.
[ENAMETOOLONG] The name string is longer than
[ENOENT] The flag is not set in oflag (see sem_open(2)) and the named semaphore does not exist.
SEE ALSO
sem_close(2), sem_open(2), privileges(5), <semaphore.h>.
STANDARDS CONFORMANCE
sem_unlink(2)