February 2012
Intermediate to advanced
1184 pages
37h 17m
English
Content preview from Programming Perl, 4th Editionsemctl
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semctl 
semctlID,SEMNUM,CMD,ARG
This function calls the System V IPC function
semctl(2). You’ll probably have to say use IPC::SysV first to get the correct
constant definitions. If CMD is IPC_STAT or GETALL, then ARG
must be a variable that will hold the returned semid_ds structure or semaphore value array.
As with ioctl and fcntl, return values are undef for error, “0
but true” for zero, and the actual return value
otherwise.
See also the IPC::Semaphore module. This function is available only on machines
supporting System V IPC.
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