Working with the Unix OS

Interprocess Communication
#include
main ()
{
int msqid;
msqid = msgget((key_t)10, IPC_CREAT);
printf("Message queue created with key %d\n", msqid);
}
$ipcs -q
IPC status from /dev/krnem as of Mon May 3 22:30:31 1993
T ID KEY MODE OWNER GROUP
Message Queues:
q 0 0x0000000a ---------- neville staff
struct ipc_perm {
ushort uid; /* owners user id */
ushort gid; /* owners group id */
ushort cuid; /* creators user id */
ushort cgid; /* creators group id */
ushort mode; /* access modes */
ushort seq; /* slot usage sequence nice number */
key_t key; /* key; */
};
/* -------------------------------------- */
#include
#include
#include
main ( )
{
int msqid;
key_t key = 32769;
msqid = msgget(key, IPC_CREAT | IPC_EXCL);
if (msqid < 0)
perror ("msgget failed");
else
printf ("Message queue created with key %d\n", msqid);
}
$ipcrrn -q
QUEUE PERMISSIONS
#include
#include
#include
main()
{
int msqid;
key_t key = 15;
msqid = msgget(key, IPC_CREAT | 0644);
if (msqid < 0)
perror("msgget failed");
else
printf ("Message queue created with key %d\n", msqid);
}
$ipcs -q
IPC status from /dev/krnem as of Mon May 3 22:30:31 1993
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