msgget(2) System Calls Manual msgget(2) msgget - System V (libc -lc) #include int msgget(key_t key, int msgflg); msgget() System V key. ( msgflg key IPC_PRIVATE) . key IPC_PRIVATE key IPC_PRIVATE key IPC_CREAT msgflg. msgflg IPC_CREAT IPC_EXCL key msgget() errno EEXIST. ( O_CREAT | O_EXCL open(2).) msgflg . mode open(2). ( .) msqid_ds ( msgctl(2)) : o msg_perm.cuid msg_perm.uid . o msg_perm.cgid msg_perm.gid . o 9 msg_perm.mode 9 msgflg. o msg_qnum msg_lspid msg_lrpid msg_stime msg_rtime 0. o msg_ctime . o msg_qbytes MSGMNB. . msgget() ( ). -1 errno . EACCES key CAP_IPC_OWNER IPC . EEXIST IPC_CREAT IPC_EXCL msgflg key. ENOENT key msgflg IPC_CREAT. ENOMEM . ENOSPC (MSGMNI). POSIX.1-2024 XSI. SVr4, SUSv1, POSIX.1-2001 XSI. Linux 2.3.20 Linux EIDRM msgget() . IPC_PRIVATE key_t. key 9 msgflg ( ). msgget(): MSGMNI . Linux 3.19 . Linux 3.19 32,000. Linux /proc/sys/kernel/msgmni. IPC_PRIVATE IPC_NEW . msgctl(2), msgrcv(2), msgsnd(2), ftok(3), capabilities(7), mq_overview(7), sysvipc(7) 3 . . : . 6.18 11 2026 msgget(2)