Error installing R package e1071

I wanted to play around with the Floyd-Warshall algorithm today. Lucky for me, it’s included as part of the e1071 package. When I tried to install it – from the CRAN repository and from source – I got

ERROR: 'configure' exists but is not executable

The solution (from a recent post on Jonathan Callahan’s blog) is to “set the TMPDIR environment variable which R will use as the compilation directory.” For me, this meant

$ mkdir ~/tmp
$ export TMPDIR=~/tmp