[R] Convert Unix (Epoch) timestamp to DD/MM/YY and HH:MM:SS

[Jim Hargreaves]

Dear List,

After much searching with no success, I would like to ask how I can 
convert a unix/POSIX time (seconds since Jan 01, 1970) into a string 
like "01/01/1970 00:00"

This is probably easily done with a system(date...) but it would be 
great if I could do it in R.

Kind Regards,
Jim Hargreaves