Outputs the name of the logger that published the logging event. The logger conversion specifier can be optionally followed by precision specifier, which consists of a decimal integer, or a pattern starting with a decimal integer.

When the precision specifier is an integer value, it reduces the size of the logger name. If the number is positive, the layout prints the corresponding number of rightmost logger name components. If negative, the layout removes the corresponding number of leftmost logger name components.

If the precision contains any non-integer characters, then the layout abbreviates the name based on the pattern. If the precision integer is less than one, the layout still prints the right-most token in full. By default, the layout prints the logger name in full.

Outputs the date of the logging event. The date conversion specifier may be followed by a set of braces containing a date and time pattern string per SimpleDateFormat .

The predefined named formats are:

You can also use a set of braces containing a time zone id per java.util.TimeZone.getTimeZone. If no date format specifier is given then the DEFAULT format is used.

You can define custom date formats:

%d{UNIX} outputs the UNIX time in seconds. %d{UNIX_MILLIS} outputs the UNIX time in milliseconds. The UNIX time is the difference, in seconds for UNIX and in milliseconds for UNIX_MILLIS, between the current time and midnight, January 1, 1970 UTC. While the time unit is milliseconds, the granularity depends on the operating system (Windows). This is an efficient way to output the event time because only a conversion from long to String takes place, there is no Date formatting involved.

Log4j 2.11 adds limited support for timestamps more precise than milliseconds when running on Java 9. Note that not all DateTimeFormatter formats are supported. Only timestamps in the formats mentioned in the table above may use the "nano-of-second" pattern letter n instead of the "fraction-of-second" pattern letter S.

Users may revert back to a millisecond-precision clock when running on Java 9 by setting system property log4j2.Clock to SystemMillisClock.

Outputs the Throwable trace bound to the logging event, by default this will output the full trace as one would normally find with a call to Throwable.printStackTrace().

You can follow the throwable conversion word with an option in the form %throwable{option}.

%throwable{short} outputs the first line of the Throwable.

%throwable{short.className} outputs the name of the class where the exception occurred.

%throwable{short.methodName} outputs the method name where the exception occurred.

%throwable{short.fileName} outputs the name of the class where the exception occurred.

%throwable{short.lineNumber} outputs the line number where the exception occurred.

%throwable{short.message} outputs the message.

%throwable{short.localizedMessage} outputs the localized message.

%throwable{n} outputs the first n lines of the stack trace.

Specifying %throwable{none} or %throwable{0} suppresses output of the exception.

Use {filters(packages)} where packages is a list of package names to suppress matching stack frames from stack traces.

Use {suffix(pattern)} to add the output of pattern at the end of each stack frames.

Use a {separator(...)} as the end-of-line string. For example: separator(|). The default value is the line.separator system property, which is operating system dependent.

Adds ANSI colors to the result of the enclosed pattern based on the current event's logging level. (See Jansi configuration.)

The default colors for each level are:

The color names are ANSI names defined in the AnsiEscape class.

The color and attribute names and are standard, but the exact shade, hue, or value.

You can use the default colors with:

%highlight{%d [%t] %-5level: %msg%n%throwable}

You can override the default colors in the optional {style} option. For example:

%highlight{%d [%t] %-5level: %msg%n%throwable}{FATAL=white, ERROR=red, WARN=blue, INFO=black, DEBUG=green, TRACE=blue}

You can highlight only the a portion of the log event:

%d [%t] %highlight{%-5level: %msg%n%throwable}

You can style one part of the message and highlight the rest the log event:

%style{%d [%t]}{black} %highlight{%-5level: %msg%n%throwable}

You can also use the STYLE key to use a predefined group of colors:

%highlight{%d [%t] %-5level: %msg%n%throwable}{STYLE=Logback}

Outputs location information of the caller which generated the logging event.

The location information depends on the JVM implementation but usually consists of the fully qualified name of the calling method followed by the callers source the file name and line number between parentheses.

Generating location information is an expensive operation and may impact performance. Use with caution.

Outputs the application supplied message associated with the logging event.

Add {ansi} to render messages with ANSI escape codes (requires JAnsi, see configuration.)

The default syntax for embedded ANSI codes is:

@|code(,code)* text|@

For example, to render the message "Hello" in green, use:

@|green Hello|@

To render the message "Hello" in bold and red, use:

@|bold,red Warning!|@

You can also define custom style names in the configuration with the syntax:

%message{ansi}{StyleName=value(,value)*( StyleName=value(,value)*)*}%n

For example:

%message{ansi}{WarningStyle=red,bold KeyStyle=white ValueStyle=blue}%n

The call site can look like this:

logger.info("@|KeyStyle {}|@ = @|ValueStyle {}|@", entry.getKey(), entry.getValue());

Use {nolookups} to log messages like "${date:YYYY-MM-dd}" without using any lookups. Normally calling logger.info("Try ${date:YYYY-MM-dd}") would replace the date template ${date:YYYY-MM-dd} with an actual date. Using nolookups disables this feature and logs the message string untouched.

Outputs the result of evaluating the pattern and truncating the result. If the length is greater than 20, then the output will contain a trailing ellipsis. If the provided length is invalid, a default value of 100 is used.

Example syntax: %maxLen{%p: %c{1} - %m%notEmpty{ =>%ex{short}}}{160} will be limited to 160 characters with a trailing ellipsis. Another example: %maxLen{%m}{20} will be limited to 20 characters and no trailing ellipsis.

Outputs the result of System.nanoTime() at the time the log event was created.

Outputs the result of evaluating the pattern if and only if all variables in the pattern are not empty.

For example:

%notEmpty{[%marker]}

The same as the %throwable conversion word but the stack trace is printed starting with the first exception that was thrown followed by each subsequent wrapping exception.

The throwable conversion word can be followed by an option in the form %rEx{short} which will only output the first line of the Throwable or %rEx{n} where the first n lines of the stack trace will be printed.

Specifying %rEx{none} or %rEx{0} will suppress printing of the exception.

Use filters(packages) where packages is a list of package names to suppress matching stack frames from stack traces.

Use a separator string to separate the lines of a stack trace. For example: separator(|). The default value is the line.separator system property, which is operating system dependent.

Use rEx{suffix(pattern) to add the output of pattern to the output only when there is a throwable to print.

Uses ANSI escape sequences to style the result of the enclosed pattern. The style can consist of a comma separated list of style names from the following table. (See Jansi configuration.)

For example:

%style{%d{ISO8601}}{black} %style{[%t]}{blue} %style{%-5level:}{yellow} %style{%msg%n%throwable}{green}

You can also combine styles:

%d %highlight{%p} %style{%logger}{bright,cyan} %C{1.} %msg%n

You can also use % with a color like %black, %blue, %cyan, and so on. For example:

%black{%d{ISO8601}} %blue{[%t]} %yellow{%-5level:} %green{%msg%n%throwable}

If true, the appender includes the location information in the generated XML. Defaults to false.

Generating location information is an expensive operation and may impact performance. Use with caution.