gettz 
Get System Timezone Information
Motivation
Many date and time conversion need information about the local timezone. It
is common to set the environment variable TZ. However, sometimes it is
unset, and we need a fallback. Or maybe we just want a fallback to not
always have to set the TZ variable by hand.
R has a helper function Sys.timezone() which queries the system timezone
information. Sadly, we have seen it fail (possibly because /etc/localtime
was not a symbolic link as it expected, but rather a copy of the
corresponding (local) timezone metadata). Another issue is, once again, that
the code which R uses here is sadly not accessible to users via a callable
API for C or C++. So there is a need for something different---and Duane
McCully provided just that
in this StackOverflow answer. This
package essentially adapted his code to be callable from R.
Status
Works on Linux, expected to also work on Solaris and BSD, builds on OS
X but only returns NULL due to the apparent lack of any programmatic
interface.
Windows could possibly be supported by querying the registry.
Installation
The package is now on CRAN and can be installed via a standard
R> install.packages("gettz")provided you are on a Unix system.
Author
Dirk Eddelbuettel
License
GPL (>= 2)
