date-format
The date-format variable followed by a space, specifies the log-format date containing any combination of regular characters and special format specifiers. They all begin with a percentage (%) sign. See `man strftime`.
%b
The abbreviated month name according to the current
locale. (Calculated from tm_mon.) (The specific names
used in the current locale can be obtained by calling
nl_langinfo(3) with ABMON_{1–12} as an argument.)