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<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE chapter SYSTEM "chapter.dtd">
<chapter>
<header>
<copyright>
<year>2003</year><year>2018</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
</legalnotice>
<title>Error Logging</title>
<prepared></prepared>
<docno></docno>
<date></date>
<rev></rev>
<file>error_logging.xml</file>
</header>
<marker id="error logging"></marker>
<section>
<title>Error Information From the Runtime System</title>
<p>Error information from the runtime system, that is, information
about a process terminating because of an uncaught error exception,
is by default written to terminal (tty):</p>
<code type="none"><![CDATA[
=ERROR REPORT==== 9-Dec-2003::13:25:02 ===
Error in process <0.27.0> with exit value: {{badmatch,[1,2,3]},[{m,f,1},{shell,eval_loop,2}]}]]></code>
<p>The error information is handled by Logger, which is part of
the Kernel application.</p>
<p>The exit reasons (such as <c>badarg</c>) used by
the runtime system are described in
<seealso marker="doc/reference_manual:errors#exit_reasons">
Errors and Error Handling</seealso>.</p>
<p>For information about Logger and its user
interface, see the
<seealso marker="kernel:logger">logger(3)</seealso>
manual page and
the <seealso marker="kernel:logger_chapter">Logging</seealso>
section in the Kernel User's Guide. The system can be configured so that
log events are
written to file or to tty, or both. In addition, user-defined
applications can send and format log events using
Logger.</p>
</section>
<section>
<title>Log events from OTP behaviours</title>
<p>The standard behaviours (<c>supervisor</c>, <c>gen_server</c>,
and so on) send progress and error information to
Logger. Progress reports are by default not logged, but can be
enabled by setting the primary log level to <c>info</c>, for
example by using the Kernel configuration
parameter <c>logger_level</c>. Supervisor reports, crash reports
and other error and information reports are by default logged
through the log handler which is set up when the Kernel
application is started.</p>
<p>Prior to Erlang/OTP 21.0, supervisor, crash, and progress
reports were only logged when the SASL application was
running. This behaviour can, for backwards compatibility, be
enabled by setting the Kernel configuration
parameter <seealso marker="kernel:kernel_app#logger_sasl_compatible">
<c>logger_sasl_compatible</c></seealso>
to <c>true</c>. For more information, see
<seealso marker="sasl:error_logging">SASL Error Logging</seealso>
in the SASL User's Guide.</p>
<pre>
% <input>erl -kernel logger_level info</input>
Erlang/OTP 21 [erts-10.0] [source-13c50db] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe]
=PROGRESS REPORT==== 8-Jun-2018::16:54:19.916404 ===
application: kernel
started_at: nonode@nohost
=PROGRESS REPORT==== 8-Jun-2018::16:54:19.922908 ===
application: stdlib
started_at: nonode@nohost
=PROGRESS REPORT==== 8-Jun-2018::16:54:19.925755 ===
supervisor: {local,kernel_safe_sup}
started: [{pid,<0.74.0>},
{id,disk_log_sup},
{mfargs,{disk_log_sup,start_link,[]}},
{restart_type,permanent},
{shutdown,1000},
{child_type,supervisor}]
=PROGRESS REPORT==== 8-Jun-2018::16:54:19.926056 ===
supervisor: {local,kernel_safe_sup}
started: [{pid,<0.75.0>},
{id,disk_log_server},
{mfargs,{disk_log_server,start_link,[]}},
{restart_type,permanent},
{shutdown,2000},
{child_type,worker}]
Eshell V10.0 (abort with ^G)
1> </pre>
</section>
</chapter>
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