projects / thirdparty / man-pages.git / blame
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1 | .\" Copyright (c) 2019 by Michael Kerrisk <mtk.manpages@gmail.com> |
| 2 | .\" | |
| 5fbde956 | 3 | .\" SPDX-License-Identifier: Linux-man-pages-copyleft |
| 1d36b4e1 MK |
4 | .\" |
| 5 | .\" | |
| 45186a5d | 6 | .TH IPC_NAMESPACES 7 2019-08-02 "Linux man-pages (unreleased)" |
| 1d36b4e1 | 7 | .SH NAME |
| 1f294696 | 8 | ipc_namespaces \- overview of Linux IPC namespaces |
| 1d36b4e1 MK |
9 | .SH DESCRIPTION |
| 10 | IPC namespaces isolate certain IPC resources, | |
| 11 | namely, System V IPC objects (see | |
| 12 | .BR sysvipc (7)) | |
| 13 | and (since Linux 2.6.30) | |
| 14 | .\" commit 7eafd7c74c3f2e67c27621b987b28397110d643f | |
| 15 | .\" https://lwn.net/Articles/312232/ | |
| 16 | POSIX message queues (see | |
| 17 | .BR mq_overview (7)). | |
| 18 | The common characteristic of these IPC mechanisms is that IPC | |
| 19 | objects are identified by mechanisms other than filesystem | |
| 20 | pathnames. | |
| 21 | .PP | |
| 22 | Each IPC namespace has its own set of System V IPC identifiers and | |
| 23 | its own POSIX message queue filesystem. | |
| 24 | Objects created in an IPC namespace are visible to all other processes | |
| 25 | that are members of that namespace, | |
| 26 | but are not visible to processes in other IPC namespaces. | |
| 27 | .PP | |
| 28 | The following | |
| 29 | .I /proc | |
| 30 | interfaces are distinct in each IPC namespace: | |
| 31 | .IP * 3 | |
| 32 | The POSIX message queue interfaces in | |
| 33 | .IR /proc/sys/fs/mqueue . | |
| 34 | .IP * | |
| 35 | The System V IPC interfaces in | |
| 36 | .IR /proc/sys/kernel , | |
| 37 | namely: | |
| 38 | .IR msgmax , | |
| 39 | .IR msgmnb , | |
| 40 | .IR msgmni , | |
| 41 | .IR sem , | |
| 42 | .IR shmall , | |
| 43 | .IR shmmax , | |
| 44 | .IR shmmni , | |
| 45 | and | |
| 46 | .IR shm_rmid_forced . | |
| 47 | .IP * | |
| 48 | The System V IPC interfaces in | |
| 49 | .IR /proc/sysvipc . | |
| 50 | .PP | |
| 51 | When an IPC namespace is destroyed | |
| 52 | (i.e., when the last process that is a member of the namespace terminates), | |
| 53 | all IPC objects in the namespace are automatically destroyed. | |
| 54 | .PP | |
| 55 | Use of IPC namespaces requires a kernel that is configured with the | |
| 56 | .B CONFIG_IPC_NS | |
| 57 | option. | |
| 58 | .SH SEE ALSO | |
| 59 | .BR nsenter (1), | |
| 60 | .BR unshare (1), | |
| 61 | .BR clone (2), | |
| 62 | .BR setns (2), | |
| 63 | .BR unshare (2), | |
| 64 | .BR mq_overview (7), | |
| 65 | .BR namespaces (7), | |
| 66 | .BR sysvipc (7) |