The FileHandler class allows the substitution of paths such as the user's home directory or the system's temporary directory.
The forward slash (/) is used as a directory separator/
The forward slash (/) works for both Unix and Windows machines.
The FileHandler class supported to specify where the generation number goes in the filename when log files are rotated.
These patterns are each prefixed with a percent sign (%).
To include the percent sign in the filename, specify two percent signs (%%).
The following table contains all the valid percent-sign substitutions.
PatternDescription
%tFull path of the system temporary directory
%hValue of the user.home system property
%gGeneration number used to distinguish rotated logs
%uUnique number used to resolve process conflicts