Sys.setFileTime(path, time)
"POSIXct"
or an object which can
be coerced to one. Fractions of a second are ignored.
On a Unix-alike it uses the system call utimes
if that is
available, otherwise utimes
. On a POSIX file system it sets
both the last-access and modification times.
On Windows it uses the system call SetFileTime
to set the
last write time. Some Windows file systems only record the
time at a resolution of two seconds.