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<img alt="Erlang logo" src="../../../../doc/erlang-logo.png"><br><small><a href="index.html">Reference Manual</a><br><a href="release_notes.html">Release Notes</a><br><a href="../pdf/kernel-2.15.3.pdf">PDF</a><br><a href="../../../../doc/index.html">Top</a></small><p><strong>Kernel</strong><br><strong>Reference Manual</strong><br><small>Version 2.15.3</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">
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<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>
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<li title="takeover-2"><a href="application.html#takeover-2">takeover/2</a></li>
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<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>
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<li title="Module:config_change-3"><a href="application.html#Module:config_change-3">Module:config_change/3</a></li>
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<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>
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<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>
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<li title="is_loaded-1"><a href="code.html#is_loaded-1">is_loaded/1</a></li>
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<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>
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<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>
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<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>
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<li id="no" title="disk_log " expanded="false">disk_log<ul>
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<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>
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<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
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<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">
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</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">
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<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>
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<li title="change_time-2"><a href="file.html#change_time-2">change_time/2</a></li>
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<li title="close-1"><a href="file.html#close-1">close/1</a></li>
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<li id="no" title="gen_tcp " expanded="false">gen_tcp<ul>
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</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 title="controlling_process-2"><a href="gen_tcp.html#controlling_process-2">controlling_process/2</a></li>
<li title="close-1"><a href="gen_tcp.html#close-1">close/1</a></li>
<li title="shutdown-2"><a href="gen_tcp.html#shutdown-2">shutdown/2</a></li>
</ul>
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<li title="open-1"><a href="gen_udp.html#open-1">open/1</a></li>
<li title="open-2"><a href="gen_udp.html#open-2">open/2</a></li>
<li title="send-4"><a href="gen_udp.html#send-4">send/4</a></li>
<li title="recv-2"><a href="gen_udp.html#recv-2">recv/2</a></li>
<li title="recv-3"><a href="gen_udp.html#recv-3">recv/3</a></li>
<li title="controlling_process-2"><a href="gen_udp.html#controlling_process-2">controlling_process/2</a></li>
<li title="close-1"><a href="gen_udp.html#close-1">close/1</a></li>
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<li id="no" title="gen_sctp " expanded="false">gen_sctp<ul>
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<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="peeloff-2"><a href="gen_sctp.html#peeloff-2">peeloff/2</a></li>
<li title="recv-1"><a href="gen_sctp.html#recv-1">recv/1</a></li>
<li title="recv-2"><a href="gen_sctp.html#recv-2">recv/2</a></li>
<li title="send-3"><a href="gen_sctp.html#send-3">send/3</a></li>
<li title="send-4"><a href="gen_sctp.html#send-4">send/4</a></li>
<li title="error_string-1"><a href="gen_sctp.html#error_string-1">error_string/1</a></li>
</ul>
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<li id="no" title="global " expanded="false">global<ul>
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<li title="del_lock-2"><a href="global.html#del_lock-2">del_lock/2</a></li>
<li title="notify_all_name-3"><a href="global.html#notify_all_name-3">notify_all_name/3</a></li>
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<li title="random_notify_name-3"><a href="global.html#random_notify_name-3">random_notify_name/3</a></li>
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<li title="register_name-3"><a 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>
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<li title="send-2"><a href="global.html#send-2">send/2</a></li>
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<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>
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<li title="trans-4"><a href="global.html#trans-4">trans/4</a></li>
<li title="unregister_name-1"><a href="global.html#unregister_name-1">unregister_name/1</a></li>
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<li title="info-0"><a href="global_group.html#info-0">info/0</a></li>
<li title="monitor_nodes-1"><a href="global_group.html#monitor_nodes-1">monitor_nodes/1</a></li>
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<li title="whereis_name-2"><a href="global_group.html#whereis_name-2">whereis_name/2</a></li>
</ul>
</li>
<li id="no" title="heart " expanded="false">heart<ul>
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<li title="set_cmd-1"><a href="heart.html#set_cmd-1">set_cmd/1</a></li>
<li title="clear_cmd-0"><a href="heart.html#clear_cmd-0">clear_cmd/0</a></li>
<li title="get_cmd-0"><a href="heart.html#get_cmd-0">get_cmd/0</a></li>
</ul>
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<li id="no" title="inet " expanded="false">inet<ul>
<li><a href="inet.html">
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<li title="close-1"><a href="inet.html#close-1">close/1</a></li>
<li title="get_rc-0"><a href="inet.html#get_rc-0">get_rc/0</a></li>
<li title="format_error-1"><a href="inet.html#format_error-1">format_error/1</a></li>
<li title="getaddr-2"><a href="inet.html#getaddr-2">getaddr/2</a></li>
<li title="getaddrs-2"><a href="inet.html#getaddrs-2">getaddrs/2</a></li>
<li title="gethostbyaddr-1"><a href="inet.html#gethostbyaddr-1">gethostbyaddr/1</a></li>
<li title="gethostbyname-1"><a href="inet.html#gethostbyname-1">gethostbyname/1</a></li>
<li title="gethostbyname-2"><a href="inet.html#gethostbyname-2">gethostbyname/2</a></li>
<li title="gethostname-0"><a href="inet.html#gethostname-0">gethostname/0</a></li>
<li title="getifaddrs-0"><a href="inet.html#getifaddrs-0">getifaddrs/0</a></li>
<li title="getopts-2"><a href="inet.html#getopts-2">getopts/2</a></li>
<li title="getstat-1"><a href="inet.html#getstat-1">getstat/1</a></li>
<li title="getstat-2"><a href="inet.html#getstat-2">getstat/2</a></li>
<li title="peername-1"><a href="inet.html#peername-1">peername/1</a></li>
<li title="port-1"><a href="inet.html#port-1">port/1</a></li>
<li title="sockname-1"><a href="inet.html#sockname-1">sockname/1</a></li>
<li title="setopts-2"><a href="inet.html#setopts-2">setopts/2</a></li>
</ul>
</li>
<li id="loadscrollpos" title="inet_res " expanded="true">inet_res<ul>
<li><a href="inet_res.html">
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</a></li>
<li title="getbyname-2"><a href="inet_res.html#getbyname-2">getbyname/2</a></li>
<li title="getbyname-3"><a href="inet_res.html#getbyname-3">getbyname/3</a></li>
<li title="gethostbyaddr-1"><a href="inet_res.html#gethostbyaddr-1">gethostbyaddr/1</a></li>
<li title="gethostbyaddr-2"><a href="inet_res.html#gethostbyaddr-2">gethostbyaddr/2</a></li>
<li title="gethostbyname-1"><a href="inet_res.html#gethostbyname-1">gethostbyname/1</a></li>
<li title="gethostbyname-2"><a href="inet_res.html#gethostbyname-2">gethostbyname/2</a></li>
<li title="gethostbyname-3"><a href="inet_res.html#gethostbyname-3">gethostbyname/3</a></li>
<li title="lookup-3"><a href="inet_res.html#lookup-3">lookup/3</a></li>
<li title="lookup-4"><a href="inet_res.html#lookup-4">lookup/4</a></li>
<li title="lookup-5"><a href="inet_res.html#lookup-5">lookup/5</a></li>
<li title="resolve-3"><a href="inet_res.html#resolve-3">resolve/3</a></li>
<li title="resolve-4"><a href="inet_res.html#resolve-4">resolve/4</a></li>
<li title="resolve-5"><a href="inet_res.html#resolve-5">resolve/5</a></li>
<li title="nslookup-3"><a href="inet_res.html#nslookup-3">nslookup/3</a></li>
<li title="nslookup-4"><a href="inet_res.html#nslookup-4">nslookup/4</a></li>
<li title="nnslookup-4"><a href="inet_res.html#nnslookup-4">nnslookup/4</a></li>
<li title="nnslookup-5"><a href="inet_res.html#nnslookup-5">nnslookup/5</a></li>
</ul>
</li>
<li title="init"><a href="init.html">init</a></li>
<li id="no" title="net_adm " expanded="false">net_adm<ul>
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<li title="dns_hostname-1"><a href="net_adm.html#dns_hostname-1">dns_hostname/1</a></li>
<li title="host_file-0"><a href="net_adm.html#host_file-0">host_file/0</a></li>
<li title="localhost-0"><a href="net_adm.html#localhost-0">localhost/0</a></li>
<li title="names-0"><a href="net_adm.html#names-0">names/0</a></li>
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</ul>
</li>
<li id="no" title="net_kernel " expanded="false">net_kernel<ul>
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<li title="monitor_nodes-2"><a href="net_kernel.html#monitor_nodes-2">monitor_nodes/2</a></li>
<li title="get_net_ticktime-0"><a href="net_kernel.html#get_net_ticktime-0">get_net_ticktime/0</a></li>
<li title="set_net_ticktime-1"><a href="net_kernel.html#set_net_ticktime-1">set_net_ticktime/1</a></li>
<li title="set_net_ticktime-2"><a href="net_kernel.html#set_net_ticktime-2">set_net_ticktime/2</a></li>
<li title="start-1"><a href="net_kernel.html#start-1">start/1</a></li>
<li title="start-1"><a href="net_kernel.html#start-1">start/1</a></li>
<li title="start-1"><a href="net_kernel.html#start-1">start/1</a></li>
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</ul>
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<li id="no" title="os " expanded="false">os<ul>
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<li title="cmd-1"><a href="os.html#cmd-1">cmd/1</a></li>
<li title="find_executable-1"><a href="os.html#find_executable-1">find_executable/1</a></li>
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</ul>
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<li title="create-1"><a href="pg2.html#create-1">create/1</a></li>
<li title="delete-1"><a href="pg2.html#delete-1">delete/1</a></li>
<li title="get_closest_pid-1"><a href="pg2.html#get_closest_pid-1">get_closest_pid/1</a></li>
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<li title="get_local_members-1"><a href="pg2.html#get_local_members-1">get_local_members/1</a></li>
<li title="join-2"><a href="pg2.html#join-2">join/2</a></li>
<li title="leave-2"><a href="pg2.html#leave-2">leave/2</a></li>
<li title="which_groups-0"><a href="pg2.html#which_groups-0">which_groups/0</a></li>
<li title="start-0"><a href="pg2.html#start-0">start/0</a></li>
<li title="start_link-0"><a href="pg2.html#start_link-0">start_link/0</a></li>
</ul>
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<li id="no" title="rpc " expanded="false">rpc<ul>
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</a></li>
<li title="call-4"><a href="rpc.html#call-4">call/4</a></li>
<li title="call-5"><a href="rpc.html#call-5">call/5</a></li>
<li title="block_call-4"><a href="rpc.html#block_call-4">block_call/4</a></li>
<li title="block_call-5"><a href="rpc.html#block_call-5">block_call/5</a></li>
<li title="async_call-4"><a href="rpc.html#async_call-4">async_call/4</a></li>
<li title="yield-1"><a href="rpc.html#yield-1">yield/1</a></li>
<li title="nb_yield-1"><a href="rpc.html#nb_yield-1">nb_yield/1</a></li>
<li title="nb_yield-2"><a href="rpc.html#nb_yield-2">nb_yield/2</a></li>
<li title="multicall-3"><a href="rpc.html#multicall-3">multicall/3</a></li>
<li title="multicall-4"><a href="rpc.html#multicall-4">multicall/4</a></li>
<li title="multicall-5"><a href="rpc.html#multicall-5">multicall/5</a></li>
<li title="cast-4"><a href="rpc.html#cast-4">cast/4</a></li>
<li title="eval_everywhere-3"><a href="rpc.html#eval_everywhere-3">eval_everywhere/3</a></li>
<li title="eval_everywhere-4"><a href="rpc.html#eval_everywhere-4">eval_everywhere/4</a></li>
<li title="abcast-2"><a href="rpc.html#abcast-2">abcast/2</a></li>
<li title="abcast-3"><a href="rpc.html#abcast-3">abcast/3</a></li>
<li title="sbcast-2"><a href="rpc.html#sbcast-2">sbcast/2</a></li>
<li title="sbcast-3"><a href="rpc.html#sbcast-3">sbcast/3</a></li>
<li title="server_call-4"><a href="rpc.html#server_call-4">server_call/4</a></li>
<li title="multi_server_call-2"><a href="rpc.html#multi_server_call-2">multi_server_call/2</a></li>
<li title="multi_server_call-3"><a href="rpc.html#multi_server_call-3">multi_server_call/3</a></li>
<li title="safe_multi_server_call-2"><a href="rpc.html#safe_multi_server_call-2">safe_multi_server_call/2</a></li>
<li title="safe_multi_server_call-3"><a href="rpc.html#safe_multi_server_call-3">safe_multi_server_call/3</a></li>
<li title="parallel_eval-1"><a href="rpc.html#parallel_eval-1">parallel_eval/1</a></li>
<li title="pmap-3"><a href="rpc.html#pmap-3">pmap/3</a></li>
<li title="pinfo-1"><a href="rpc.html#pinfo-1">pinfo/1</a></li>
<li title="pinfo-2"><a href="rpc.html#pinfo-2">pinfo/2</a></li>
</ul>
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<li title="set_token-2"><a href="seq_trace.html#set_token-2">set_token/2</a></li>
<li title="get_token-0"><a href="seq_trace.html#get_token-0">get_token/0</a></li>
<li 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>
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<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>
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<li title="zlib"><a href="zlib.html">zlib</a></li>
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</div></div>
<div id="content">
<div class="innertube">
<!-- refpage --><center><h1>inet_res</h1></center>
<h3>MODULE</h3>
<div class="REFBODY">inet_res</div>
<h3>MODULE SUMMARY</h3>
<div class="REFBODY">A Rudimentary DNS Client</div>
<h3>DESCRIPTION</h3>
<div class="REFBODY"><p>
<p>Performs DNS name resolving towards recursive name servers</p>
<p>See also
<span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','inet_cfg.html');">
ERTS User's Guide: Inet configuration
</a></span> for more
information on how to configure an Erlang runtime system for IP
communication and how to enable this DNS client by defining
<span class="code">'dns'</span> as a lookup method. It then acts
as a backend for the resolving functions in
<span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','kernel','inet.html');">inet</a></span>.</p>
<p>This DNS client can resolve DNS records even if it
is not used for normal name resolving in the node.</p>
<p>This is not a full-fledged resolver. It is just a
DNS client that relies on asking trusted recursive nameservers.</p>
</p></div>
<h3><a name="id129787">Name Resolving</a></h3>
<div class="REFBODY">
<p>UDP queries are used unless resolver option
<span class="code">usevc</span> is <span class="code">true</span>, which forces TCP queries.
If the query is to large for UDP, TCP is used instead.
For regular DNS queries 512 bytes is the size limit.
When EDNS is enabled (resolver option
<span class="code">edns</span> is set to the EDNS version i.e <span class="code">0</span>
instead of <span class="code">false</span>), resolver option
<span class="code">udp_payload_size</span> sets the limit. If a nameserver
replies with the TC bit set (truncation), indicating
the answer is incomplete, the query is retried
to that nameserver using TCP. The resolver option
<span class="code">udp_payload_size</span> also sets the advertised
size for the max allowed reply size, if EDNS is
enabled, otherwise the nameserver uses the limit
512 byte. If the reply is larger it gets truncated,
forcing a TCP re-query.</p>
<p>For UDP queries, the resolver options <span class="code">timeout</span>
and <span class="code">retry</span> control retransmission.
Each nameserver in the <span class="code">nameservers</span> list is
tried with a timeout of <span class="code">timeout</span> / <span class="code">retry</span>.
Then all nameservers are tried again doubling the
timeout, for a total of <span class="code">retry</span> times.</p>
<p>For queries that not use the <span class="code">search</span> list,
if the query to all <span class="code">nameservers</span> results in
<span class="code">{error,nxdomain}</span>or an empty answer, the same
query is tried for the <span class="code">alt_nameservers</span>.</p>
</div>
<h3>DATA TYPES</h3>
<p>Resolver types:</p>
<p>
<span class="bold_code"><a name="type-res_option">res_option()</a> = {alt_nameservers, [<span class="bold_code"><a href="#type-nameserver">nameserver()</a></span>]}<br> | {edns, 0 | false}<br> | {inet6, boolean()}<br> | {nameservers, [<span class="bold_code"><a href="#type-nameserver">nameserver()</a></span>]}<br> | {recurse, boolean()}<br> | {retry, integer()}<br> | {timeout, integer()}<br> | {udp_payload_size, integer()}<br> | {usevc, boolean()}</span><br></p>
<p>
<span class="bold_code"><a name="type-nameserver">nameserver()</a> = {<span class="bold_code"><a href="inet.html#type-ip_address">inet:ip_address()</a></span>, Port :: 1..65535}</span><br></p>
<p>
<span class="bold_code"><a name="type-res_error">res_error()</a> = formerr<br> | qfmterror<br> | servfail<br> | nxdomain<br> | notimp<br> | refused<br> | badvers<br> | timeout</span><br></p>
<p><a name="dns_types"></a>DNS types:</p>
<p>
<span class="bold_code"><a name="type-dns_name">dns_name()</a> = string()</span><br></p>
<div class="REFBODY"><p><p>A string with no adjacent dots.</p></p></div>
<p>
<span class="bold_code"><a name="type-rr_type">rr_type()</a> = a<br> | aaaa<br> | cname<br> | gid<br> | hinfo<br> | ns<br> | mb<br> | md<br> | mg<br> | mf<br> | minfo<br> | mx<br> | naptr<br> | null<br> | ptr<br> | soa<br> | spf<br> | srv<br> | txt<br> | uid<br> | uinfo<br> | unspec<br> | wks</span><br></p>
<p>
<span class="bold_code"><a name="type-dns_class">dns_class()</a> = in | chaos | hs | any</span><br></p>
<p>
<span class="bold_code"><a name="type-dns_msg">dns_msg()</a> = term()</span><br></p>
<div class="REFBODY"><p>
<p>This is the start of a hiearchy of opaque data structures
that can be examined with access functions in inet_dns that
return lists of {Field,Value} tuples. The arity 2 functions
just return the value for a given field.
<div class="example"><pre>
dns_msg() = DnsMsg
inet_dns:msg(DnsMsg) ->
[ {header, dns_header()}
| {qdlist, dns_query()}
| {anlist, dns_rr()}
| {nslist, dns_rr()}
| {arlist, dns_rr()} ]
inet_dns:msg(DnsMsg, header) -> dns_header() % for example
inet_dns:msg(DnsMsg, Field) -> Value
dns_header() = DnsHeader
inet_dns:header(DnsHeader) ->
[ {id, integer()}
| {qr, boolean()}
| {opcode, 'query' | iquery | status | integer()}
| {aa, boolean()}
| {tc, boolean()}
| {rd, boolean()}
| {ra, boolean()}
| {pr, boolean()}
| {rcode, integer(0..16)} ]
inet_dns:header(DnsHeader, Field) -> Value
query_type() = axfr | mailb | maila | any | rr_type()
dns_query() = DnsQuery
inet_dns:dns_query(DnsQuery) ->
[ {domain, dns_name()}
| {type, query_type()}
| {class, dns_class()} ]
inet_dns:dns_query(DnsQuery, Field) -> Value
dns_rr() = DnsRr
inet_dns:rr(DnsRr) -> DnsRrFields | DnsRrOptFields
DnsRrFields = [ {domain, dns_name()}
| {type, rr_type()}
| {class, dns_class()}
| {ttl, integer()}
| {data, dns_data()} ]
DnsRrOptFields = [ {domain, dns_name()}
| {type, opt}
| {udp_payload_size, integer()}
| {ext_rcode, integer()}
| {version, integer()}
| {z, integer()}
| {data, dns_data()} ]
inet_dns:rr(DnsRr, Field) -> Value
There is an info function for the types above:
inet_dns:record_type(dns_msg()) -> msg;
inet_dns:record_type(dns_header()) -> header;
inet_dns:record_type(dns_query()) -> dns_query;
inet_dns:record_type(dns_rr()) -> rr;
inet_dns:record_type(_) -> undefined.
So; inet_dns:(inet_dns:record_type(X))(X) will convert
any of these data structures into a {Field,Value} list.</pre></div></p>
</p></div>
<p>
<span class="bold_code"><a name="type-dns_data">dns_data()</a> = <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span><br> | <span class="bold_code"><a href="inet.html#type-ip4_address">inet:ip4_address()</a></span><br> | <span class="bold_code"><a href="inet.html#type-ip6_address">inet:ip6_address()</a></span><br> | {MName :: <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span>,<br> RName :: <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span>,<br> Serial :: integer(),<br> Refresh :: integer(),<br> Retry :: integer(),<br> Expiry :: integer(),<br> Minimum :: integer()}<br> | {<span class="bold_code"><a href="inet.html#type-ip4_address">inet:ip4_address()</a></span>,<br> Proto :: integer(),<br> BitMap :: binary()}<br> | {CpuString :: string(), OsString :: string()}<br> | {RM :: <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span>, EM :: <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span>}<br> | {Prio :: integer(), <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span>}<br> | {Prio :: integer(),<br> Weight :: integer(),<br> Port :: integer(),<br> <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span>}<br> | {Order :: integer(),<br> Preference :: integer(),<br> Flags :: string(),<br> Services :: string(),<br> Regexp :: string(),<br> <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span>}<br> | [string()]<br> | binary()</span><br></p>
<div class="REFBODY"><p><p><span class="code">Regexp</span> is a string with characters encoded in the
UTF-8 coding standard.</p>
</p></div>
<h3>EXPORTS</h3>
<p><a name="getbyname-2"></a><span class="bold_code">getbyname(Name, Type) -> {ok, Hostent} | {error, Reason}</span><br><a name="getbyname-3"></a><span class="bold_code">getbyname(Name, Type, Timeout) -> {ok, Hostent} | {error, Reason}</span><br><div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES"><span class="bold_code">Name = <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Type = <span class="bold_code"><a href="#type-rr_type">rr_type()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Timeout = timeout()</span></div>
<div class="REFTYPES"><span class="bold_code">Hostent = <span class="bold_code"><a href="inet.html#type-hostent">inet:hostent()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Reason = <span class="bold_code"><a href="inet.html#type-posix">inet:posix()</a></span> | <span class="bold_code"><a href="#type-res_error">res_error()</a></span></span></div>
</div></p>
<div class="REFBODY"><p>
<p>Resolve a DNS record of the given type for the given host,
of class <span class="code">in</span>. On success returns a <span class="code">hostent()</span> record with
<span class="code">dns_data()</span> elements in the address list field.
</p><p>
This function uses the resolver option <span class="code">search</span> that
is a list of domain names. If the name to resolve contains
no dots, it is prepended to each domain name in the
search list, and they are tried in order. If the name
contains dots, it is first tried as an absolute name
and if that fails the search list is used. If the name
has a trailing dot it is simply supposed to be
an absolute name and the search list is not used.
</p>
</p></div>
<p><a name="gethostbyaddr-1"></a><span class="bold_code">gethostbyaddr(Address) -> {ok, Hostent} | {error, Reason}</span><br><a name="gethostbyaddr-2"></a><span class="bold_code">gethostbyaddr(Address, Timeout) -> {ok, Hostent} | {error, Reason}</span><br><div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES"><span class="bold_code">Address = <span class="bold_code"><a href="inet.html#type-ip_address">inet:ip_address()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Timeout = timeout()</span></div>
<div class="REFTYPES"><span class="bold_code">Hostent = <span class="bold_code"><a href="inet.html#type-hostent">inet:hostent()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Reason = <span class="bold_code"><a href="inet.html#type-posix">inet:posix()</a></span> | <span class="bold_code"><a href="#type-res_error">res_error()</a></span></span></div>
</div></p>
<div class="REFBODY"><p>
<p>Backend functions used by
<span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','kernel','inet.html#gethostbyaddr-1');">
inet:gethostbyaddr/1
</a></span>.
</p>
</p></div>
<p><a name="gethostbyname-1"></a><span class="bold_code">gethostbyname(Name) -> {ok, Hostent} | {error, Reason}</span><br><a name="gethostbyname-2"></a><span class="bold_code">gethostbyname(Name, Family) -> {ok, Hostent} | {error, Reason}</span><br><a name="gethostbyname-3"></a><span class="bold_code">gethostbyname(Name, Family, Timeout) -><br> {ok, Hostent} | {error, Reason}</span><br><div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES"><span class="bold_code">Name = <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Hostent = <span class="bold_code"><a href="inet.html#type-hostent">inet:hostent()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Timeout = timeout()</span></div>
<div class="REFTYPES"><span class="bold_code">Family = <span class="bold_code"><a href="inet.html#type-address_family">inet:address_family()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Reason = <span class="bold_code"><a href="inet.html#type-posix">inet:posix()</a></span> | <span class="bold_code"><a href="#type-res_error">res_error()</a></span></span></div>
</div></p>
<div class="REFBODY"><p>
<p>Backend functions used by
<span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','kernel','inet.html#gethostbyname-1');">
inet:gethostbyname/1,2
</a></span>.
</p><p>
This function uses the resolver option <span class="code">search</span> just like
<span class="bold_code"><a href="#getbyname-2">getbyname/2,3</a></span>.
</p><p>
If the resolver option <span class="code">inet6</span> is <span class="code">true</span>,
an IPv6 address is looked up, and if that fails
the IPv4 address is looked up and returned on
IPv6 mapped IPv4 format.
</p>
</p></div>
<p><a name="lookup-3"></a><span class="bold_code">lookup(Name, Class, Type) -> [<span class="bold_code"><a href="#type-dns_data">dns_data()</a></span>]</span><br><a name="lookup-4"></a><span class="bold_code">lookup(Name, Class, Type, Opts) -> [<span class="bold_code"><a href="#type-dns_data">dns_data()</a></span>]</span><br><a name="lookup-5"></a><span class="bold_code">lookup(Name, Class, Type, Opts, Timeout) -> [<span class="bold_code"><a href="#type-dns_data">dns_data()</a></span>]</span><br><div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES"><span class="bold_code">Name = <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span> | <span class="bold_code"><a href="inet.html#type-ip_address">inet:ip_address()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Class = <span class="bold_code"><a href="#type-dns_class">dns_class()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Type = <span class="bold_code"><a href="#type-rr_type">rr_type()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Opts = [<span class="bold_code"><a href="#type-res_option">res_option()</a></span> | verbose]</span></div>
<div class="REFTYPES"><span class="bold_code">Timeout = timeout()</span></div>
</div></p>
<div class="REFBODY"><p>
<p>Resolve the DNS data for the record of the given type and class
for the given name. On success filters out the answer records
with the correct <span class="code">Class</span> and <span class="code">Type</span> and returns
a list of their data fields. So a lookup for type <span class="code">any</span>
will give an empty answer since the answer records have
specific types that are not <span class="code">any</span>. An empty answer
as well as a failed lookup returns an empty list.
</p><p>
Calls <span class="bold_code"><a href="#resolve-3">resolve/2..4</a></span>
with the same arguments and filters the result, so
<span class="code">Opts</span> is explained there.
</p>
</p></div>
<p><a name="resolve-3"></a><span class="bold_code">resolve(Name, Class, Type) -> {ok, <span class="bold_code"><a href="#type-dns_msg">dns_msg()</a></span>} | Error</span><br><a name="resolve-4"></a><span class="bold_code">resolve(Name, Class, Type, Opts) -> {ok, <span class="bold_code"><a href="#type-dns_msg">dns_msg()</a></span>} | Error</span><br><a name="resolve-5"></a><span class="bold_code">resolve(Name, Class, Type, Opts, Timeout) -><br> {ok, <span class="bold_code"><a href="#type-dns_msg">dns_msg()</a></span>} | Error</span><br><div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES"><span class="bold_code">Name = <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span> | <span class="bold_code"><a href="inet.html#type-ip_address">inet:ip_address()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Class = <span class="bold_code"><a href="#type-dns_class">dns_class()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Type = <span class="bold_code"><a href="#type-rr_type">rr_type()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Opts = [Opt]</span></div>
<div class="REFTYPES"><span class="bold_code">Opt = <span class="bold_code"><a href="#type-res_option">res_option()</a></span> | verbose | atom()</span></div>
<div class="REFTYPES"><span class="bold_code">Timeout = timeout()</span></div>
<div class="REFTYPES"><span class="bold_code">Error = {error, Reason} | {error, {Reason, <span class="bold_code"><a href="#type-dns_msg">dns_msg()</a></span>}}</span></div>
<div class="REFTYPES"><span class="bold_code">Reason = <span class="bold_code"><a href="inet.html#type-posix">inet:posix()</a></span> | <span class="bold_code"><a href="#type-res_error">res_error()</a></span></span></div>
</div></p>
<div class="REFBODY"><p>
<p>Resolve a DNS record of the given type and class for the given name.
The returned <span class="code">dns_msg()</span> can be examined using
access functions in <span class="code">inet_db</span> as described
in <span class="bold_code"><a href="#dns_types">DNS types</a></span>.
</p><p>
If <span class="code">Name</span> is an <span class="code">ip_address()</span>, the domain name
to query for is generated as the standard reverse
".IN-ADDR.ARPA." name for an IPv4 address, or the
".IP6.ARPA." name for an IPv6 address.
In this case you most probably want to use
<span class="code">Class = in</span> and <span class="code">Type = ptr</span> but it
is not done automatically.
</p><p>
<span class="code">Opts</span> override the corresponding resolver options.
If the option <span class="code">nameservers</span> is given, it is
also assumed that it is the complete list of nameserves,
so the resolver option <span class="code">alt_nameserves</span> is ignored.
Of course, if that option is also given to this function,
it is used.
</p><p>
The <span class="code">verbose</span> option (or rather <span class="code">{verbose,true}</span>),
causes diagnostics printout through
<span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','stdlib','io.html#format-3');">io:format/2</a></span>
of queries, replies retransmissions, etc, similar
to from utilities like <span class="code">dig</span>, <span class="code">nslookup</span> et.al.
</p><p>
If <span class="code">Opt</span> is an arbitrary atom it is interpreted
as <span class="code">{Opt,true}</span> unless the atom string starts with
<span class="code">"no"</span> making the interpretation <span class="code">{Opt,false}</span>.
For example: <span class="code">usevc</span> is an alias for <span class="code">{usevc,true}</span>,
and <span class="code">nousevc</span> an alias for <span class="code">{usevc,false}</span>.
</p><p>
The <span class="code">inet6</span> option currently has no effect on this function.
You probably want to use <span class="code">Type = a | aaaa</span> instead.
</p>
</p></div>
<h3><a name="id130400">Examples</a></h3>
<div class="REFBODY">
<p>Access functions example: how
<span class="bold_code"><a href="#lookup-3">lookup/3</a></span>
could have been implemented using
<span class="bold_code"><a href="#resolve-3">resolve/3</a></span>
from outside the module.
</p>
<div class="example"><pre>
example_lookup(Name, Class, Type) ->
case inet_res:resolve(Name, Class, Type) of
{ok,Msg} ->
[inet_dns:rr(RR, data)
|| RR <- inet_dns:msg(Msg, anlist),
inet_dns:rr(RR, type) =:= Type,
inet_dns:rr(RR, class) =:= Class];
{error,_} ->
[]
end.</pre></div>
</div>
<h3><a name="id130432">Legacy Functions</a></h3>
<div class="REFBODY">
<p>These have been deprecated due to the annoying double
meaning of the nameservers/timeout argument, and
because they had no decent place for a resolver options list.</p>
</div>
<h3>EXPORTS</h3>
<p><a name="nslookup-3"></a><span class="bold_code">nslookup(Name, Class, Type) -> {ok, <span class="bold_code"><a href="#type-dns_msg">dns_msg()</a></span>} | {error, Reason}</span><br><a name="nslookup-4"></a><span class="bold_code">nslookup(Name, Class, Type, Timeout) -><br> {ok, <span class="bold_code"><a href="#type-dns_msg">dns_msg()</a></span>} | {error, Reason}</span><br><span class="bold_code">nslookup(Name, Class, Type, Nameservers) -><br> {ok, <span class="bold_code"><a href="#type-dns_msg">dns_msg()</a></span>} | {error, Reason}</span><br><div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES"><span class="bold_code">Name = <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span> | <span class="bold_code"><a href="inet.html#type-ip_address">inet:ip_address()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Class = <span class="bold_code"><a href="#type-dns_class">dns_class()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Type = <span class="bold_code"><a href="#type-rr_type">rr_type()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Timeout = timeout()</span></div>
<div class="REFTYPES"><span class="bold_code">Nameservers = [<span class="bold_code"><a href="#type-nameserver">nameserver()</a></span>]</span></div>
<div class="REFTYPES"><span class="bold_code">Reason = <span class="bold_code"><a href="inet.html#type-posix">inet:posix()</a></span> | <span class="bold_code"><a href="#type-res_error">res_error()</a></span></span></div>
</div></p>
<div class="REFBODY"><p>
<p>Resolve a DNS record of the given type and class for the given name.
</p>
</p></div>
<p><a name="nnslookup-4"></a><span class="bold_code">nnslookup(Name, Class, Type, Nameservers) -><br> {ok, <span class="bold_code"><a href="#type-dns_msg">dns_msg()</a></span>} | {error, Reason}</span><br><a name="nnslookup-5"></a><span class="bold_code">nnslookup(Name, Class, Type, Nameservers, Timeout) -><br> {ok, <span class="bold_code"><a href="#type-dns_msg">dns_msg()</a></span>} | {error, Reason}</span><br><div class="REFBODY">
<p>Types:</p>
<div class="REFTYPES"><span class="bold_code">Name = <span class="bold_code"><a href="#type-dns_name">dns_name()</a></span> | <span class="bold_code"><a href="inet.html#type-ip_address">inet:ip_address()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Class = <span class="bold_code"><a href="#type-dns_class">dns_class()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Type = <span class="bold_code"><a href="#type-rr_type">rr_type()</a></span></span></div>
<div class="REFTYPES"><span class="bold_code">Timeout = timeout()</span></div>
<div class="REFTYPES"><span class="bold_code">Nameservers = [<span class="bold_code"><a href="#type-nameserver">nameserver()</a></span>]</span></div>
<div class="REFTYPES"><span class="bold_code">Reason = <span class="bold_code"><a href="inet.html#type-posix">inet:posix()</a></span></span></div>
</div></p>
<div class="REFBODY"><p>
<p>Resolve a DNS record of the given type and class for the given name.
</p>
</p></div>
</div>
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