<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html xmlns:fn="http://www.w3.org/2005/02/xpath-functions"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <link rel="stylesheet" href="../../../../doc/otp_doc.css" type="text/css"> <title>Erlang -- global_group</title> </head> <body bgcolor="white" text="#000000" link="#0000ff" vlink="#ff00ff" alink="#ff0000"><div id="container"> <script id="js" type="text/javascript" language="JavaScript" src="../../../../doc/js/flipmenu/flipmenu.js"></script><script id="js2" type="text/javascript" src="../../../../doc/js/erlresolvelinks.js"></script><script language="JavaScript" type="text/javascript"> <!-- function getWinHeight() { var myHeight = 0; if( typeof( window.innerHeight ) == 'number' ) { //Non-IE myHeight = window.innerHeight; } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) { //IE 6+ in 'standards compliant mode' myHeight = 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href="../../../../doc/index.html">Top</a></small><p><strong>Kernel</strong><br><strong>Reference Manual</strong><br><small>Version 2.14.5</small></p> <br><a href="javascript:openAllFlips()">Expand All</a><br><a href="javascript:closeAllFlips()">Contract All</a><p><small><strong>Table of Contents</strong></small></p> <ul class="flipMenu"> <li title="kernel (App)"><a href="kernel_app.html">kernel (App) </a></li> <li id="no" title="application " expanded="false">application<ul> <li><a href="application.html"> Top of manual page </a></li> <li title="get_all_env-0"><a href="application.html#get_all_env-0">get_all_env/0</a></li> <li title="get_all_env-1"><a href="application.html#get_all_env-1">get_all_env/1</a></li> <li title="get_all_key-0"><a href="application.html#get_all_key-0">get_all_key/0</a></li> <li title="get_all_key-1"><a href="application.html#get_all_key-1">get_all_key/1</a></li> <li title="get_application-0"><a href="application.html#get_application-0">get_application/0</a></li> <li title="get_application-1"><a href="application.html#get_application-1">get_application/1</a></li> <li title="get_env-1"><a href="application.html#get_env-1">get_env/1</a></li> <li title="get_env-2"><a href="application.html#get_env-2">get_env/2</a></li> <li title="get_key-1"><a href="application.html#get_key-1">get_key/1</a></li> <li title="get_key-2"><a href="application.html#get_key-2">get_key/2</a></li> <li title="load-1"><a href="application.html#load-1">load/1</a></li> <li title="load-2"><a href="application.html#load-2">load/2</a></li> <li title="loaded_applications-0"><a href="application.html#loaded_applications-0">loaded_applications/0</a></li> <li title="permit-2"><a href="application.html#permit-2">permit/2</a></li> <li title="set_env-3"><a href="application.html#set_env-3">set_env/3</a></li> <li title="set_env-4"><a href="application.html#set_env-4">set_env/4</a></li> <li title="start-1"><a href="application.html#start-1">start/1</a></li> <li title="start-2"><a href="application.html#start-2">start/2</a></li> <li title="start_type-0"><a href="application.html#start_type-0">start_type/0</a></li> <li title="stop-1"><a href="application.html#stop-1">stop/1</a></li> <li title="takeover-2"><a href="application.html#takeover-2">takeover/2</a></li> <li title="unload-1"><a href="application.html#unload-1">unload/1</a></li> <li title="unset_env-2"><a href="application.html#unset_env-2">unset_env/2</a></li> <li title="unset_env-3"><a href="application.html#unset_env-3">unset_env/3</a></li> <li title="which_applications-0"><a href="application.html#which_applications-0">which_applications/0</a></li> <li title="which_applications-1"><a href="application.html#which_applications-1">which_applications/1</a></li> <li title="Module:start-2"><a href="application.html#Module:start-2">Module:start/2</a></li> <li title="Module:start_phase-3"><a href="application.html#Module:start_phase-3">Module:start_phase/3</a></li> <li title="Module:prep_stop-1"><a href="application.html#Module:prep_stop-1">Module:prep_stop/1</a></li> <li title="Module:stop-1"><a href="application.html#Module:stop-1">Module:stop/1</a></li> <li title="Module:config_change-3"><a href="application.html#Module:config_change-3">Module:config_change/3</a></li> </ul> </li> <li id="no" title="auth " expanded="false">auth<ul> <li><a href="auth.html"> Top of manual page </a></li> <li title="is_auth-1"><a href="auth.html#is_auth-1">is_auth/1</a></li> <li title="cookie-0"><a href="auth.html#cookie-0">cookie/0</a></li> <li title="cookie-1"><a href="auth.html#cookie-1">cookie/1</a></li> <li title="node_cookie-1"><a href="auth.html#node_cookie-1">node_cookie/1</a></li> <li title="node_cookie-2"><a href="auth.html#node_cookie-2">node_cookie/2</a></li> </ul> </li> <li id="no" title="code " expanded="false">code<ul> <li><a href="code.html"> Top of manual page </a></li> <li title="set_path-1"><a href="code.html#set_path-1">set_path/1</a></li> <li title="get_path-0"><a href="code.html#get_path-0">get_path/0</a></li> <li title="add_path-1"><a href="code.html#add_path-1">add_path/1</a></li> <li title="add_pathz-1"><a href="code.html#add_pathz-1">add_pathz/1</a></li> <li title="add_patha-1"><a href="code.html#add_patha-1">add_patha/1</a></li> <li title="add_paths-1"><a href="code.html#add_paths-1">add_paths/1</a></li> <li title="add_pathsz-1"><a href="code.html#add_pathsz-1">add_pathsz/1</a></li> <li title="add_pathsa-1"><a href="code.html#add_pathsa-1">add_pathsa/1</a></li> <li title="del_path-1"><a href="code.html#del_path-1">del_path/1</a></li> <li title="replace_path-2"><a href="code.html#replace_path-2">replace_path/2</a></li> <li title="load_file-1"><a href="code.html#load_file-1">load_file/1</a></li> <li title="load_abs-1"><a href="code.html#load_abs-1">load_abs/1</a></li> <li title="ensure_loaded-1"><a href="code.html#ensure_loaded-1">ensure_loaded/1</a></li> <li title="load_binary-3"><a href="code.html#load_binary-3">load_binary/3</a></li> <li title="delete-1"><a href="code.html#delete-1">delete/1</a></li> <li title="purge-1"><a href="code.html#purge-1">purge/1</a></li> <li title="soft_purge-1"><a href="code.html#soft_purge-1">soft_purge/1</a></li> <li title="is_loaded-1"><a href="code.html#is_loaded-1">is_loaded/1</a></li> <li title="all_loaded-0"><a href="code.html#all_loaded-0">all_loaded/0</a></li> <li title="which-1"><a href="code.html#which-1">which/1</a></li> <li title="get_object_code-1"><a href="code.html#get_object_code-1">get_object_code/1</a></li> <li title="root_dir-0"><a href="code.html#root_dir-0">root_dir/0</a></li> <li title="lib_dir-0"><a href="code.html#lib_dir-0">lib_dir/0</a></li> <li title="lib_dir-1"><a href="code.html#lib_dir-1">lib_dir/1</a></li> <li title="lib_dir-2"><a href="code.html#lib_dir-2">lib_dir/2</a></li> <li title="compiler_dir-0"><a href="code.html#compiler_dir-0">compiler_dir/0</a></li> <li title="priv_dir-1"><a href="code.html#priv_dir-1">priv_dir/1</a></li> <li title="objfile_extension-0"><a href="code.html#objfile_extension-0">objfile_extension/0</a></li> <li title="stick_dir-1"><a href="code.html#stick_dir-1">stick_dir/1</a></li> <li title="unstick_dir-1"><a href="code.html#unstick_dir-1">unstick_dir/1</a></li> <li title="is_sticky-1"><a href="code.html#is_sticky-1">is_sticky/1</a></li> <li title="rehash-0"><a href="code.html#rehash-0">rehash/0</a></li> <li title="where_is_file-1"><a href="code.html#where_is_file-1">where_is_file/1</a></li> <li title="clash-0"><a href="code.html#clash-0">clash/0</a></li> <li title="is_module_native-1"><a href="code.html#is_module_native-1">is_module_native/1</a></li> </ul> </li> <li id="no" title="disk_log " expanded="false">disk_log<ul> <li><a href="disk_log.html"> Top of manual page </a></li> <li title="accessible_logs-0"><a href="disk_log.html#accessible_logs-0">accessible_logs/0</a></li> <li title="alog-2"><a href="disk_log.html#alog-2">alog/2</a></li> <li title="balog-2"><a href="disk_log.html#balog-2">balog/2</a></li> <li title="alog_terms-2"><a href="disk_log.html#alog_terms-2">alog_terms/2</a></li> <li title="balog_terms-2"><a href="disk_log.html#balog_terms-2">balog_terms/2</a></li> <li title="block-1"><a href="disk_log.html#block-1">block/1</a></li> <li title="block-2"><a href="disk_log.html#block-2">block/2</a></li> <li title="change_header-2"><a href="disk_log.html#change_header-2">change_header/2</a></li> <li title="change_notify-3"><a href="disk_log.html#change_notify-3">change_notify/3</a></li> <li title="change_size-2"><a href="disk_log.html#change_size-2">change_size/2</a></li> <li title="chunk-2"><a href="disk_log.html#chunk-2">chunk/2</a></li> <li title="chunk-3"><a href="disk_log.html#chunk-3">chunk/3</a></li> <li title="bchunk-2"><a href="disk_log.html#bchunk-2">bchunk/2</a></li> <li title="bchunk-3"><a href="disk_log.html#bchunk-3">bchunk/3</a></li> <li title="chunk_info-1"><a href="disk_log.html#chunk_info-1">chunk_info/1</a></li> <li title="chunk_step-3"><a href="disk_log.html#chunk_step-3">chunk_step/3</a></li> <li title="close-1"><a href="disk_log.html#close-1">close/1</a></li> <li title="format_error-1"><a href="disk_log.html#format_error-1">format_error/1</a></li> <li title="inc_wrap_file-1"><a href="disk_log.html#inc_wrap_file-1">inc_wrap_file/1</a></li> <li title="info-1"><a href="disk_log.html#info-1">info/1</a></li> <li title="lclose-1"><a href="disk_log.html#lclose-1">lclose/1</a></li> <li title="lclose-2"><a href="disk_log.html#lclose-2">lclose/2</a></li> <li title="log-2"><a href="disk_log.html#log-2">log/2</a></li> <li title="blog-2"><a href="disk_log.html#blog-2">blog/2</a></li> <li title="log_terms-2"><a href="disk_log.html#log_terms-2">log_terms/2</a></li> <li title="blog_terms-2"><a href="disk_log.html#blog_terms-2">blog_terms/2</a></li> <li title="open-1"><a href="disk_log.html#open-1">open/1</a></li> <li title="pid2name-1"><a href="disk_log.html#pid2name-1">pid2name/1</a></li> <li title="reopen-2"><a href="disk_log.html#reopen-2">reopen/2</a></li> <li title="reopen-3"><a href="disk_log.html#reopen-3">reopen/3</a></li> <li title="breopen-3"><a href="disk_log.html#breopen-3">breopen/3</a></li> <li title="sync-1"><a href="disk_log.html#sync-1">sync/1</a></li> <li title="truncate-1"><a href="disk_log.html#truncate-1">truncate/1</a></li> <li title="truncate-2"><a href="disk_log.html#truncate-2">truncate/2</a></li> <li title="btruncate-2"><a href="disk_log.html#btruncate-2">btruncate/2</a></li> <li title="unblock-1"><a href="disk_log.html#unblock-1">unblock/1</a></li> </ul> </li> <li id="no" title="erl_boot_server " expanded="false">erl_boot_server<ul> <li><a href="erl_boot_server.html"> Top of manual page </a></li> <li title="start-1"><a href="erl_boot_server.html#start-1">start/1</a></li> <li title="start_link-1"><a href="erl_boot_server.html#start_link-1">start_link/1</a></li> <li title="add_slave-1"><a href="erl_boot_server.html#add_slave-1">add_slave/1</a></li> <li title="delete_slave-1"><a href="erl_boot_server.html#delete_slave-1">delete_slave/1</a></li> <li title="which_slaves-0"><a href="erl_boot_server.html#which_slaves-0">which_slaves/0</a></li> </ul> </li> <li id="no" title="erl_ddll " expanded="false">erl_ddll<ul> <li><a href="erl_ddll.html"> Top of manual page </a></li> <li title="demonitor-1"><a href="erl_ddll.html#demonitor-1">demonitor/1</a></li> <li title="info-0"><a href="erl_ddll.html#info-0">info/0</a></li> <li title="info-1"><a href="erl_ddll.html#info-1">info/1</a></li> <li title="info-2"><a href="erl_ddll.html#info-2">info/2</a></li> <li title="load-2"><a href="erl_ddll.html#load-2">load/2</a></li> <li title="load_driver-2"><a href="erl_ddll.html#load_driver-2">load_driver/2</a></li> <li title="monitor-2"><a href="erl_ddll.html#monitor-2">monitor/2</a></li> <li title="reload-2"><a href="erl_ddll.html#reload-2">reload/2</a></li> <li title="reload_driver-2"><a href="erl_ddll.html#reload_driver-2">reload_driver/2</a></li> <li title="try_load-3"><a href="erl_ddll.html#try_load-3">try_load/3</a></li> <li title="try_unload-2"><a href="erl_ddll.html#try_unload-2">try_unload/2</a></li> <li title="unload-1"><a href="erl_ddll.html#unload-1">unload/1</a></li> <li title="unload_driver-1"><a href="erl_ddll.html#unload_driver-1">unload_driver/1</a></li> <li title="loaded_drivers-0"><a href="erl_ddll.html#loaded_drivers-0">loaded_drivers/0</a></li> <li title="format_error-1"><a href="erl_ddll.html#format_error-1">format_error/1</a></li> </ul> </li> <li title="erl_prim_loader"><a href="erl_prim_loader.html">erl_prim_loader</a></li> <li title="erlang"><a href="erlang.html">erlang</a></li> <li id="no" title="error_handler " expanded="false">error_handler<ul> <li><a href="error_handler.html"> Top of manual page </a></li> <li title="undefined_function-3"><a href="error_handler.html#undefined_function-3">undefined_function/3</a></li> <li title="undefined_lambda-3"><a href="error_handler.html#undefined_lambda-3">undefined_lambda/3</a></li> </ul> </li> <li id="no" title="error_logger " expanded="false">error_logger<ul> <li><a href="error_logger.html"> Top of manual page </a></li> <li title="error_msg-1"><a href="error_logger.html#error_msg-1">error_msg/1</a></li> <li title="error_msg-2"><a href="error_logger.html#error_msg-2">error_msg/2</a></li> <li title="format-2"><a href="error_logger.html#format-2">format/2</a></li> <li title="error_report-1"><a href="error_logger.html#error_report-1">error_report/1</a></li> <li title="error_report-2"><a href="error_logger.html#error_report-2">error_report/2</a></li> <li title="warning_map-0"><a href="error_logger.html#warning_map-0">warning_map/0</a></li> <li title="warning_msg-1"><a href="error_logger.html#warning_msg-1">warning_msg/1</a></li> <li title="warning_msg-2"><a href="error_logger.html#warning_msg-2">warning_msg/2</a></li> <li title="warning_report-1"><a href="error_logger.html#warning_report-1">warning_report/1</a></li> <li title="warning_report-2"><a href="error_logger.html#warning_report-2">warning_report/2</a></li> <li title="info_msg-1"><a href="error_logger.html#info_msg-1">info_msg/1</a></li> <li title="info_msg-2"><a href="error_logger.html#info_msg-2">info_msg/2</a></li> <li title="info_report-1"><a href="error_logger.html#info_report-1">info_report/1</a></li> <li title="info_report-2"><a href="error_logger.html#info_report-2">info_report/2</a></li> <li title="add_report_handler-1"><a href="error_logger.html#add_report_handler-1">add_report_handler/1</a></li> <li title="add_report_handler-2"><a href="error_logger.html#add_report_handler-2">add_report_handler/2</a></li> <li title="delete_report_handler-1"><a href="error_logger.html#delete_report_handler-1">delete_report_handler/1</a></li> <li title="tty-1"><a href="error_logger.html#tty-1">tty/1</a></li> <li title="logfile-1"><a href="error_logger.html#logfile-1">logfile/1</a></li> </ul> </li> <li id="no" title="file " expanded="false">file<ul> <li><a href="file.html"> Top of manual page </a></li> <li title="advise-4"><a href="file.html#advise-4">advise/4</a></li> <li title="change_group-2"><a href="file.html#change_group-2">change_group/2</a></li> <li title="change_mode-2"><a href="file.html#change_mode-2">change_mode/2</a></li> <li title="change_owner-2"><a href="file.html#change_owner-2">change_owner/2</a></li> <li title="change_owner-3"><a href="file.html#change_owner-3">change_owner/3</a></li> <li title="change_time-2"><a href="file.html#change_time-2">change_time/2</a></li> <li title="change_time-3"><a href="file.html#change_time-3">change_time/3</a></li> <li title="close-1"><a href="file.html#close-1">close/1</a></li> <li title="consult-1"><a href="file.html#consult-1">consult/1</a></li> <li title="copy-2"><a href="file.html#copy-2">copy/2</a></li> <li title="copy-3"><a href="file.html#copy-3">copy/3</a></li> <li title="del_dir-1"><a href="file.html#del_dir-1">del_dir/1</a></li> <li title="delete-1"><a href="file.html#delete-1">delete/1</a></li> <li title="eval-1"><a href="file.html#eval-1">eval/1</a></li> <li title="eval-2"><a href="file.html#eval-2">eval/2</a></li> <li title="file_info-1"><a href="file.html#file_info-1">file_info/1</a></li> <li title="format_error-1"><a href="file.html#format_error-1">format_error/1</a></li> <li title="get_cwd-0"><a href="file.html#get_cwd-0">get_cwd/0</a></li> <li title="get_cwd-1"><a href="file.html#get_cwd-1">get_cwd/1</a></li> <li title="list_dir-1"><a href="file.html#list_dir-1">list_dir/1</a></li> <li title="make_dir-1"><a href="file.html#make_dir-1">make_dir/1</a></li> <li title="make_link-2"><a href="file.html#make_link-2">make_link/2</a></li> <li title="make_symlink-2"><a href="file.html#make_symlink-2">make_symlink/2</a></li> <li title="native_name_encoding-0"><a href="file.html#native_name_encoding-0">native_name_encoding/0</a></li> <li title="open-2"><a href="file.html#open-2">open/2</a></li> <li title="path_consult-2"><a href="file.html#path_consult-2">path_consult/2</a></li> <li title="path_eval-2"><a href="file.html#path_eval-2">path_eval/2</a></li> <li title="path_open-3"><a href="file.html#path_open-3">path_open/3</a></li> <li title="path_script-2"><a href="file.html#path_script-2">path_script/2</a></li> <li title="path_script-3"><a href="file.html#path_script-3">path_script/3</a></li> <li title="pid2name-1"><a href="file.html#pid2name-1">pid2name/1</a></li> <li title="position-2"><a href="file.html#position-2">position/2</a></li> <li title="pread-2"><a href="file.html#pread-2">pread/2</a></li> <li title="pread-3"><a href="file.html#pread-3">pread/3</a></li> <li title="pwrite-2"><a href="file.html#pwrite-2">pwrite/2</a></li> <li title="pwrite-3"><a href="file.html#pwrite-3">pwrite/3</a></li> <li title="read-2"><a href="file.html#read-2">read/2</a></li> <li title="read_file-1"><a href="file.html#read_file-1">read_file/1</a></li> <li title="read_file_info-1"><a href="file.html#read_file_info-1">read_file_info/1</a></li> <li title="read_line-1"><a href="file.html#read_line-1">read_line/1</a></li> <li title="read_link-1"><a href="file.html#read_link-1">read_link/1</a></li> <li title="read_link_info-1"><a href="file.html#read_link_info-1">read_link_info/1</a></li> <li title="rename-2"><a href="file.html#rename-2">rename/2</a></li> <li title="script-1"><a href="file.html#script-1">script/1</a></li> <li title="script-2"><a href="file.html#script-2">script/2</a></li> <li title="set_cwd-1"><a href="file.html#set_cwd-1">set_cwd/1</a></li> <li title="sync-1"><a href="file.html#sync-1">sync/1</a></li> <li title="datasync-1"><a href="file.html#datasync-1">datasync/1</a></li> <li title="truncate-1"><a href="file.html#truncate-1">truncate/1</a></li> <li title="write-2"><a href="file.html#write-2">write/2</a></li> <li title="write_file-2"><a href="file.html#write_file-2">write_file/2</a></li> <li title="write_file-3"><a href="file.html#write_file-3">write_file/3</a></li> <li title="write_file_info-2"><a href="file.html#write_file_info-2">write_file_info/2</a></li> </ul> </li> <li id="no" title="gen_tcp " expanded="false">gen_tcp<ul> <li><a href="gen_tcp.html"> Top of manual page </a></li> <li title="connect-3"><a href="gen_tcp.html#connect-3">connect/3</a></li> <li title="connect-4"><a href="gen_tcp.html#connect-4">connect/4</a></li> <li title="listen-2"><a href="gen_tcp.html#listen-2">listen/2</a></li> <li title="accept-1"><a href="gen_tcp.html#accept-1">accept/1</a></li> <li title="accept-2"><a href="gen_tcp.html#accept-2">accept/2</a></li> <li title="send-2"><a href="gen_tcp.html#send-2">send/2</a></li> <li title="recv-2"><a href="gen_tcp.html#recv-2">recv/2</a></li> <li title="recv-3"><a href="gen_tcp.html#recv-3">recv/3</a></li> <li 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</a></li> <li title="abort-2"><a href="gen_sctp.html#abort-2">abort/2</a></li> <li title="close-1"><a href="gen_sctp.html#close-1">close/1</a></li> <li title="connect-4"><a href="gen_sctp.html#connect-4">connect/4</a></li> <li title="connect-5"><a href="gen_sctp.html#connect-5">connect/5</a></li> <li title="connect_init-4"><a href="gen_sctp.html#connect_init-4">connect_init/4</a></li> <li title="connect_init-5"><a href="gen_sctp.html#connect_init-5">connect_init/5</a></li> <li title="controlling_process-2"><a href="gen_sctp.html#controlling_process-2">controlling_process/2</a></li> <li title="eof-2"><a href="gen_sctp.html#eof-2">eof/2</a></li> <li title="listen-2"><a href="gen_sctp.html#listen-2">listen/2</a></li> <li title="open-0"><a href="gen_sctp.html#open-0">open/0</a></li> <li title="open-1"><a href="gen_sctp.html#open-1">open/1</a></li> <li title="open-2"><a href="gen_sctp.html#open-2">open/2</a></li> <li title="recv-1"><a href="gen_sctp.html#recv-1">recv/1</a></li> <li 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href="global.html#register_name-3">register_name/3</a></li> <li title="registered_names-0"><a href="global.html#registered_names-0">registered_names/0</a></li> <li title="re_register_name-2"><a href="global.html#re_register_name-2">re_register_name/2</a></li> <li title="re_register_name-3"><a href="global.html#re_register_name-3">re_register_name/3</a></li> <li title="send-2"><a href="global.html#send-2">send/2</a></li> <li title="set_lock-1"><a href="global.html#set_lock-1">set_lock/1</a></li> <li title="set_lock-2"><a href="global.html#set_lock-2">set_lock/2</a></li> <li title="set_lock-3"><a href="global.html#set_lock-3">set_lock/3</a></li> <li title="sync-0"><a href="global.html#sync-0">sync/0</a></li> <li title="trans-2"><a href="global.html#trans-2">trans/2</a></li> <li title="trans-3"><a href="global.html#trans-3">trans/3</a></li> <li title="trans-4"><a href="global.html#trans-4">trans/4</a></li> <li title="unregister_name-1"><a 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title="get_token-1"><a href="seq_trace.html#get_token-1">get_token/1</a></li> <li title="print-1"><a href="seq_trace.html#print-1">print/1</a></li> <li title="print-2"><a href="seq_trace.html#print-2">print/2</a></li> <li title="reset_trace-0"><a href="seq_trace.html#reset_trace-0">reset_trace/0</a></li> <li title="set_system_tracer-1"><a href="seq_trace.html#set_system_tracer-1">set_system_tracer/1</a></li> <li title="get_system_tracer-0"><a href="seq_trace.html#get_system_tracer-0">get_system_tracer/0</a></li> </ul> </li> <li title="user"><a href="user.html">user</a></li> <li id="no" title="wrap_log_reader " expanded="false">wrap_log_reader<ul> <li><a href="wrap_log_reader.html"> Top of manual page </a></li> <li title="chunk-1"><a href="wrap_log_reader.html#chunk-1">chunk/1</a></li> <li title="chunk-2"><a href="wrap_log_reader.html#chunk-2">chunk/2</a></li> <li title="close-1"><a href="wrap_log_reader.html#close-1">close/1</a></li> <li title="open-1"><a href="wrap_log_reader.html#open-1">open/1</a></li> <li title="open-2"><a href="wrap_log_reader.html#open-2">open/2</a></li> </ul> </li> <li title="zlib"><a href="zlib.html">zlib</a></li> <li title="app"><a href="app.html">app</a></li> <li title="config"><a href="config.html">config</a></li> <li id="no" title="packages " expanded="false">packages<ul> <li><a href="packages.html"> Top of manual page </a></li> <li title="-0"><a href="packages.html#-0">/0</a></li> </ul> </li> </ul> </div></div> <div id="content"> <div class="innertube"> <!-- refpage --><center><h1>global_group</h1></center> <h3>MODULE</h3> <div class="REFBODY">global_group</div> <h3>MODULE SUMMARY</h3> <div class="REFBODY">Grouping Nodes to Global Name Registration Groups</div> <h3>DESCRIPTION</h3> <div class="REFBODY"><p> <p>The global group function makes it possible to group the nodes in a system into partitions, each partition having its own global name space, refer to <span class="code">global(3)</span>. These partitions are called global groups.</p> <p>The main advantage of dividing systems to global groups is that the background load decreases while the number of nodes to be updated is reduced when manipulating globally registered names.</p> <p>The Kernel configuration parameter <span class="code">global_groups</span> defines the global groups (see also <span class="bold_code"><a href="kernel_app.html">kernel(6)</a></span>, <span class="bold_code"><a href="config.html">config(4)</a></span>:</p> <div class="example"><pre> {global_groups, [GroupTuple :: group_tuple()]}</pre></div> <p>For the processes and nodes to run smoothly using the global group functionality, the following criteria must be met:</p> <ul> <li> <p>An instance of the global group server, <span class="code">global_group</span>, must be running on each node. The processes are automatically started and synchronized when a node is started.</p> </li> <li> <p>All involved nodes must agree on the global group definition, or the behavior of the system is undefined.</p> </li> <li> <p><strong>All</strong> nodes in the system should belong to exactly one global group.</p> </li> </ul> <p>In the following description, a <strong>group node</strong> is a node belonging to the same global group as the local node.</p> </p></div> <h3>DATA TYPES</h3> <p> <span class="bold_code"><a name="type-group_tuple">group_tuple()</a> = {GroupName :: <span class="bold_code"><a href="#type-group_name">group_name()</a></span>, [node()]}<br> | {GroupName :: <span class="bold_code"><a href="#type-group_name">group_name()</a></span>,<br> PublishType :: <span class="bold_code"><a href="#type-publish_type">publish_type()</a></span>,<br> [node()]}</span><br></p> <div class="REFBODY"><p> <p>A <span class="code">GroupTuple</span> without <span class="code">PublishType</span> is the same as a <span class="code">GroupTuple</span> with <span class="code">PublishType == normal</span>.</p> </p></div> <p> <span class="bold_code"><a name="type-group_name">group_name()</a> = atom()</span><br></p> <p> <span class="bold_code"><a name="type-publish_type">publish_type()</a> = hidden | normal</span><br></p> <div class="REFBODY"><p> <p>A node started with the command line flag <span class="code">-hidden</span>, see <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','erl.html');">erl(1)</a></span>, is said to be a <strong>hidden</strong> node. A hidden node will establish hidden connections to nodes not part of the same global group, but normal (visible) connections to nodes part of the same global group.</p> <p>A global group defined with <span class="code">PublishType == hidden</span>, is said to be a hidden global group. All nodes in a hidden global group are hidden nodes, regardless if they are started with the <span class="code">-hidden</span> command line flag or not.</p> </p></div> <p> <span class="bold_code"><a name="type-name">name()</a> = atom()</span><br></p> <div class="REFBODY"><p><p>A registered name.</p></p></div> <p> <span class="bold_code"><a name="type-where">where()</a> = {node, node()} | {group, <span class="bold_code"><a href="#type-group_name">group_name()</a></span>}</span><br></p> <h3>EXPORTS</h3> <p><a name="global_groups-0"></a><span class="bold_code">global_groups() -> {GroupName, GroupNames} | undefined</span><br><div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"><span class="bold_code">GroupName = <span class="bold_code"><a href="#type-group_name">group_name()</a></span></span></div> <div class="REFTYPES"><span class="bold_code">GroupNames = [GroupName]</span></div> </div></p> <div class="REFBODY"><p> <p>Returns a tuple containing the name of the global group the local node belongs to, and the list of all other known group names. Returns <span class="code">undefined</span> if no global groups are defined.</p> </p></div> <p><a name="info-0"></a><span class="bold_code">info() -> [info_item()]</span><br><div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"> <span class="bold_code">info_item() = {state, State :: sync_state()}<br> | {own_group_name, GroupName :: <span class="bold_code"><a href="#type-group_name">group_name()</a></span>}<br> | {own_group_nodes, Nodes :: [node()]}<br> | {synched_nodes, Nodes :: [node()]}<br> | {sync_error, Nodes :: [node()]}<br> | {no_contact, Nodes :: [node()]}<br> | {other_groups, Groups :: [<span class="bold_code"><a href="#type-group_tuple">group_tuple()</a></span>]}<br> | {monitoring, Pids :: [pid()]}</span><br> </div> <div class="REFTYPES"> <span class="bold_code">sync_state() = no_conf | synced</span><br> </div> </div></p> <div class="REFBODY"><p> <p>Returns a list containing information about the global groups. Each element of the list is a tuple. The order of the tuples is not defined.</p> <dl> <dt><strong><span class="code">{state, State}</span></strong></dt> <dd> <p>If the local node is part of a global group, <span class="code">State == synced</span>. If no global groups are defined, <span class="code">State == no_conf</span>.</p> </dd> <dt><strong><span class="code">{own_group_name, GroupName}</span></strong></dt> <dd> <p>The name (atom) of the group that the local node belongs to.</p> </dd> <dt><strong><span class="code">{own_group_nodes, Nodes}</span></strong></dt> <dd> <p>A list of node names (atoms), the group nodes.</p> </dd> <dt><strong><span class="code">{synced_nodes, Nodes}</span></strong></dt> <dd> <p>A list of node names, the group nodes currently synchronized with the local node.</p> </dd> <dt><strong><span class="code">{sync_error, Nodes}</span></strong></dt> <dd> <p>A list of node names, the group nodes with which the local node has failed to synchronize.</p> </dd> <dt><strong><span class="code">{no_contact, Nodes}</span></strong></dt> <dd> <p>A list of node names, the group nodes to which there are currently no connections.</p> </dd> <dt><strong><span class="code">{other_groups, Groups}</span></strong></dt> <dd> <p><span class="code">Groups</span> is a list of tuples <span class="code">{GroupName, Nodes}</span>, specifying the name and nodes of the other global groups.</p> </dd> <dt><strong><span class="code">{monitoring, Pids}</span></strong></dt> <dd> <p>A list of pids, specifying the processes which have subscribed to <span class="code">nodeup</span> and <span class="code">nodedown</span> messages.</p> </dd> </dl> </p></div> <p><a name="monitor_nodes-1"></a><span class="bold_code">monitor_nodes(Flag) -> ok</span><br><div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"><span class="bold_code">Flag = boolean()</span></div> </div></p> <div class="REFBODY"><p> <p>Depending on <span class="code">Flag</span>, the calling process starts subscribing (<span class="code">Flag == true</span>) or stops subscribing (<span class="code">Flag == false</span>) to node status change messages.</p> <p>A process which has subscribed will receive the messages <span class="code">{nodeup, Node}</span> and <span class="code">{nodedown, Node}</span> when a group node connects or disconnects, respectively.</p> </p></div> <p><a name="own_nodes-0"></a><span class="bold_code">own_nodes() -> Nodes</span><br><div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"><span class="bold_code">Nodes = [Node :: node()]</span></div> </div></p> <div class="REFBODY"><p> <p>Returns the names of all group nodes, regardless of their current status.</p> </p></div> <p><a name="registered_names-1"></a><span class="bold_code">registered_names(Where) -> Names</span><br><div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"><span class="bold_code">Where = <span class="bold_code"><a href="#type-where">where()</a></span></span></div> <div class="REFTYPES"><span class="bold_code">Names = [Name :: <span class="bold_code"><a href="#type-name">name()</a></span>]</span></div> </div></p> <div class="REFBODY"><p> <p>Returns a list of all names which are globally registered on the specified node or in the specified global group.</p> </p></div> <p><a name="send-2"></a><span class="bold_code">send(Name, Msg) -> pid() | {badarg, {Name, Msg}}</span><br><a name="send-3"></a><span class="bold_code">send(Where, Name, Msg) -> pid() | {badarg, {Name, Msg}}</span><br><div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"><span class="bold_code">Where = <span class="bold_code"><a href="#type-where">where()</a></span></span></div> <div class="REFTYPES"><span class="bold_code">Name = <span class="bold_code"><a href="#type-name">name()</a></span></span></div> <div class="REFTYPES"><span class="bold_code">Msg = term()</span></div> </div></p> <div class="REFBODY"><p> <p>Searches for <span class="code">Name</span>, globally registered on the specified node or in the specified global group, or -- if the <span class="code">Where</span> argument is not provided -- in any global group. The global groups are searched in the order in which they appear in the value of the <span class="code">global_groups</span> configuration parameter.</p> <p>If <span class="code">Name</span> is found, the message <span class="code">Msg</span> is sent to the corresponding pid. The pid is also the return value of the function. If the name is not found, the function returns <span class="code">{badarg, {Name, Msg}}</span>.</p> </p></div> <p><a name="sync-0"></a><span class="bold_code">sync() -> ok</span><br></p> <div class="REFBODY"><p> <p>Synchronizes the group nodes, that is, the global name servers on the group nodes. Also check the names globally registered in the current global group and unregisters them on any known node not part of the group.</p> <p>If synchronization is not possible, an error report is sent to the error logger (see also <span class="code">error_logger(3)</span>).</p> <p>Failure: <span class="code">{error, {'invalid global_groups definition', Bad}}</span> if the <span class="code">global_groups</span> configuration parameter has an invalid value <span class="code">Bad</span>.</p> </p></div> <p><a name="whereis_name-1"></a><span class="bold_code">whereis_name(Name) -> pid() | undefined</span><br><a name="whereis_name-2"></a><span class="bold_code">whereis_name(Where, Name) -> pid() | undefined</span><br><div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"><span class="bold_code">Where = <span class="bold_code"><a href="#type-where">where()</a></span></span></div> <div class="REFTYPES"><span class="bold_code">Name = <span class="bold_code"><a href="#type-name">name()</a></span></span></div> </div></p> <div class="REFBODY"><p> <p>Searches for <span class="code">Name</span>, globally registered on the specified node or in the specified global group, or -- if the <span class="code">Where</span> argument is not provided -- in any global group. The global groups are searched in the order in which they appear in the value of the <span class="code">global_groups</span> configuration parameter.</p> <p>If <span class="code">Name</span> is found, the corresponding pid is returned. If the name is not found, the function returns <span class="code">undefined</span>.</p> </p></div> <h3><a name="id187731">NOTE</a></h3> <div class="REFBODY"> <p>In the situation where a node has lost its connections to other nodes in its global group, but has connections to nodes in other global groups, a request from another global group may produce an incorrect or misleading result. For example, the isolated node may not have accurate information about registered names in its global group.</p> <p>Note also that the <span class="code">send/2,3</span> function is not secure.</p> <p>Distribution of applications is highly dependent of the global group definitions. It is not recommended that an application is distributed over several global groups of the obvious reason that the registered names may be moved to another global group at failover/takeover. There is nothing preventing doing this, but the application code must in such case handle the situation.</p> </div> <h3><a name="id187760">SEE ALSO</a></h3> <div class="REFBODY"> <p><span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','erl.html');">erl(1)</a></span>, <span class="bold_code"><a href="global.html">global(3)</a></span></p> </div> </div> <div class="footer"> <hr> <p>Copyright © 1997-2011 Ericsson AB. All Rights Reserved.</p> </div> </div> </div></body> </html>