Perl Networking Functions - System V IPC

msgctl(ID,CMD,ARG)
Calls the System V IPC function msgctl. If CMD is &IPC_STAT, then ARG must be a variable which will hold the returned msqid_ds structure. Returns like ioctl: the undefined value for error, "0 but true" for zero, or the actual return value otherwise.

msgget(KEY,FLAGS)
Calls the System V IPC function msgget. Returns the message queue id, or the undefined value if there is an error.

msgsnd(ID,MSG,FLAGS)
Calls the System V IPC function msgsnd to send the message MSG to the message queue ID. MSG must begin with the long integer message type, which may be created with `pack("L", $type)'. Returns true if successful, or false if there is an error.


msgrcv(ID,VAR,SIZE,TYPE,FLAGS)
Calls the System V IPC function msgrcv to receive a message from message queue ID into variable VAR with a maximum message size of SIZE. Note that if a message is received, the message type will be the first thing in VAR, and the maximum length of VAR is SIZE plus the size of the message type. Returns true if successful, or false if there is an error.

semctl(ID,SEMNUM,CMD,ARG)
Calls the System V IPC function semctl. If CMD is &IPC_STAT or &GETALL, then ARG must be a variable which will hold the returned semid_ds structure or semaphore value array. Returns like ioctl: the undefined value for error, "0 but true" for zero, or the actual return value otherwise.

semget(KEY,NSEMS,SIZE,FLAGS)
Calls the System V IPC function semget. Returns the semaphore id, or the undefined value if there is an error.

semop(KEY,OPSTRING)
Calls the System V IPC function semop to perform semaphore operations such as signaling and waiting. OPSTRING must be a packed array of semop structures. Each semop structure can be generated with `pack("sss", $semnum, $semop, $semflag)'. The number of semaphore operations is implied by the length of OPSTRING. Returns true if successful, or false if there is an error. As an example, the following code waits on semaphore $semnum of semaphore id $semid:

$semop = pack("sss", $semnum, -1, 0);
die "Semaphore trouble: $!\n" unless semop($semid, $semop);

To signal the semaphore, replace `-1' with `1'.

shmctl(ID,CMD,ARG)
Calls the System V IPC function shmctl. If CMD is &IPC_STAT, then ARG must be a variable which will hold the returned shmid_ds structure. Returns like ioctl: the undefined value for error, "0 but true" for zero, or the actual return value otherwise.

shmget(KEY,SIZE,FLAGS)
Calls the System V IPC function shmget. Returns the shared memory segment id, or the undefined value if there is an error.

shmread(ID,VAR,POS,SIZE)
shmwrite(ID,STRING,POS,SIZE)
Reads or writes the System V shared memory segment ID starting at position POS for size SIZE by attaching to it, copying in/out, and detaching from it. When reading, VAR must be a variable which will hold the data read. When writing, if STRING is too long, only SIZE bytes are used; if STRING is too short, nulls are written to fill out SIZE bytes. Returns true if successful, or false if there is an error