The SASL Application


This section describes the SASL (System Architecture Support Libraries) application which provides the following services:

  • alarm_handler
  • overload
  • rb
  • release_handler
  • systools

The SASL application also includes error_logger event handlers for formatting SASL error and crash reports.


The SASL application in OTP has nothing to do with "Simple Authentication and Security Layer" (RFC 4422).

Error Logger Event Handlers

The following error logger event handlers are used by the SASL application.


Formats and writes supervisor reports, crash reports and progress reports to stdio.


Formats and writes supervisor reports, crash report and progress report to a single file.


This error logger writes all events sent to the error logger to disk.

To activate this event handler, the following three sasl configuration parameters must be set: error_logger_mf_dir, error_logger_mf_maxbytes and error_logger_mf_maxfiles. See below for more information about the configuration parameters.


The following configuration parameters are defined for the SASL application. See app(4) for more information about configuration parameters:

sasl_error_logger = Value <optional>

Value is one of:

Installs sasl_report_tty_h in the error logger. This is the default option.
Installs sasl_report_file_h in the error logger. This makes all reports go to the file FileName. FileName is a string.

No SASL error logger handler is installed.

errlog_type = error | progress | all <optional>

Restricts the error logging performed by the specified sasl_error_logger to error reports, progress reports, or both. Default is all.

error_logger_mf_dir = string() | false<optional>

Specifies in which directory the files are stored. If this parameter is undefined or false, the log_mf_h handler is not installed.

error_logger_mf_maxbytes = integer() <optional>

Specifies how large each individual file can be. If this parameter is undefined, the log_mf_h handler is not installed.

error_logger_mf_maxfiles = 0<integer()<256 <optional>

Specifies how many files are used. If this parameter is undefined, the log_mf_h handler is not installed.

overload_max_intensity = float() > 0 <optional>

Specifies the maximum intensity for overload. Default is 0.8.

overload_weight = float() > 0 <optional>

Specifies the overload weight. Default is 0.1.

start_prg = string() <optional>

Specifies which program should be used when restarting the system. Default is $OTP_ROOT/bin/start.

masters = [atom()] <optional>

Specifies which nodes this node uses to read/write release information. This parameter is ignored if the client_directory parameter is not set.

client_directory = string() <optional>

This parameter specifies the client directory at the master nodes. Refer to Release Handling in OTP Design Principles for more information. This parameter is ignored if the masters parameter is not set.

static_emulator = true | false <optional>

Indicates if the Erlang emulator is statically installed. A node with a static emulator cannot switch dynamically to a new emulator as the executable files are written into memory statically. This parameter is ignored if the masters and client_directory parameters are not set.

releases_dir = string() <optional>

Indicates where the releases directory is located. The release handler writes all its files to this directory. If this parameter is not set, the OS environment parameter RELDIR is used. By default, this is $OTP_ROOT/releases.

utc_log = true | false <optional>

If set to true, all dates in textual log outputs are displayed in Universal Coordinated Time with the string UTC appended.

See Also