The engine function has one argument options
: the
source code of the current chunk is in
options$code
. Usually we can call external
programs to run the code via system
.
Other chunk options are also contained in this argument,
e.g. options$echo
and options$eval
, etc. In most cases, options$engine
can be directly used
in command line to execute the code, e.g. python
or ruby
, but sometimes we may want to specify the
path of the engine program, in which case we can pass it
through the engine.path
option. For example,
engine='ruby', engine.path='/usr/bin/ruby1.9.1'
.
Additional command line arguments can be passed through
options$engine.opts
, e.g. engine='ruby',
engine.opts='-v'
.