perl function semget

The semget function in Perl is used to create or access a semaphore set.

Here's an example of using semget to create a new semaphore set:

use IPC::Semaphore;

my $semid = semget(1234, 1, 0666 | IPC_CREAT) or die $!; # create a new semaphore set
print "Semaphore ID: $semid\n"; # print the ID of the semaphore set

In this example, the semget function is used to create a new semaphore set with an ID of 1234 and one semaphore. The 0666 parameter specifies the permissions for the semaphore set, and the IPC_CREAT flag indicates that a new semaphore set should be created if one with the specified ID does not already exist. If an error occurs, the semget function will return undef and the die function will print the error message.

The semget function returns the ID of the semaphore set, which is then printed using the print function.

Here's an example of using semget to access an existing semaphore set:

use IPC::Semaphore;

my $semid = semget(1234, 0, 0) or die $!; # access an existing semaphore set
print "Semaphore ID: $semid\n"; # print the ID of the semaphore set

In this example, the semget function is used to access an existing semaphore set with an ID of 1234. The second parameter is set to 0, which means that the semaphore set is not created if it does not already exist. The third parameter is also set to 0, which means that the permissions for the semaphore set are not modified. If an error occurs, the semget function will return undef and the die function will print the error message.

The semget function returns the ID of the semaphore set, which is then printed using the print function.