{"id":441,"date":"2020-08-18T19:23:47","date_gmt":"2020-08-18T20:23:47","guid":{"rendered":"http:\/\/www.linux-tutorial.info\/?page_id=77"},"modified":"2020-08-22T19:26:19","modified_gmt":"2020-08-22T20:26:19","slug":"this-is-the-page-title-toplevel-274","status":"publish","type":"page","link":"http:\/\/www.linux-tutorial.info\/?page_id=441","title":{"rendered":"Sockets"},"content":{"rendered":"\n<title>Sockets<\/title>\n<p>\n<h3>System V IPC Mechanisms<\/h3>\nLinux supports three types of interprocess communication mechanisms that first\nappeared in Unix <sup><font size=-4><tt>T<\/tt>M<\/font><\/sup>&nbsp;System V (1983).\nThese are message queues, semaphores and shared memory.\nThese System V IPC mechanisms all share common authentication methods.\nProcesses may access these resources only by passing a unique reference identifier\nto the kernel via system calls.\nAccess to these System V IPC objects is checked using access permissions, much like\naccesses to files are checked.\nThe access rights to the System V IPC object is set by the creator of the object\nvia system calls.\nThe object&#8217;s reference identifier is used by each mechanism as an index into a table of\nresources.\nIt is not a straightforward index but requires some manipulation to\ngenerate it.\n<p>\nAll Linux data structures representing System V IPC objects in the system include an <tt>ipc_perm<\/tt>\nstructure which contains the owner and creator process&#8217;s user and group identifiers.\nThe access mode for this object (owner, group and other) and the IPC object&#8217;s key.\nThe key is used as a way of locating the System V IPC object&#8217;s reference identifier.\nTwo sets of keys are supported: public and private.\nIf the key is public then any process in the system, subject to rights checking, can\nfind the reference identifier for the System V IPC object.\nSystem V IPC objects can never be referenced with a key, only by their reference\nidentifier.\n<p>\n","protected":false},"excerpt":{"rendered":"<p>Sockets System V IPC Mechanisms Linux supports three types of interprocess communication mechanisms that first appeared in Unix TM&nbsp;System V (1983). These are message queues, semaphores and shared memory. These System V IPC mechanisms all share common authentication methods. Processes &hellip; <a href=\"http:\/\/www.linux-tutorial.info\/?page_id=441\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-441","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/pages\/441","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=441"}],"version-history":[{"count":1,"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/pages\/441\/revisions"}],"predecessor-version":[{"id":705,"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/pages\/441\/revisions\/705"}],"wp:attachment":[{"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=441"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}