Add support for %z (offset from UTC) in dateformat

[markkuleinio]

I'm proposing adding support for %z (offset from UTC) in dateformat.

From https://man7.org/linux/man-pages/man3/strftime.3.html:

%z The +hhmm or -hhmm numeric timezone (that is, the hour and minute offset from UTC).

Use case is hourly log rotation configurations where using local timestamps are desired. Without the UTC offset there will be duplicate file names when DST ends.

Without %z the only logrotate-only workaround I know to get unique hour-based file names is adding the unix timestamp with %s, but it provides confusingly long string of numbers.

(My current workaround is using a fixed string "-rotated" for dateformat and using a lastaction to run a Python script that renames the files to the desired syntax.)

[cgzones]

Please give #594 a try.

[markkuleinio]

Seems to work:

$ cat logrotate.conf
/home/markku/temp/logrotate-3.21.0/test.log
{
...
        dateformat -%Y%m%d-%H%z
}
$ ./logrotate -f logrotate.conf
$ ls test.log*
test.log-20240321-17+0200.gz
$