The log message to be formatted/computed.
The message format to use
The formatted log message.
%b
: short UTC month name (Jan–Dec)%c
: UTC timestamp shortcut (Mon dd hh:mm:ss)%d
: 2-digit UTC day of month (01–31)%e
: 2-digit UTC month with leading whitespace for single-digit months ( 1–12)%H
: 2-digit UTC hour (00–23)%l
: log level%M
: 2-digit UTC minute (00–59)%m
: 2-digit UTC month (01–12)%p
: prefix (with trailing delimiter if present)%S
: 2-digit UTC second (00–59)%s
: message contents%Y
: 4-digit UTC year
Formats the log message