EXTERNAL-PROGRAM enables running programs outside the Lisp process. It is an attempt to make the RUN-PROGRAM functionality in implementations like SBCL and CCL as portable as possible without sacrificing much in the way of power.

Note: This library is available via Quicklisp.

Here are some of the differences:

• splits START (async) and RUN (sync) into two separate functions, rather than using a single function with a WAIT parameter that changes the function's specification;
• offers a REPLACE-ENVIRONMENT-P parameter that indicates whether provided env vars should build on or replace the current environment.

Read the API documention for details. It’s a bit spartan, but should explain a lot.

Not all functionality is available on all platforms. EXTERNAL-PROGRAM provides warnings and errors when these limitations are encountered. But I'll try my best to work around them.

There is currently at least some support for:

• Allegro (blocking only)
• Armed Bear (blocking only)
• CLisp
• Clozure CL (née OpenMCL)
• CMUCL
• ECL
• LispWorks
• SBCL

In addition to some implementations only providing blocking calls, some don’t use $PATH – the ones that don’t won’t find bareword commands, you’ll need to use a pathname.