The UNIX extension is loaded by evaluating
(require 'unix)
This causes the files unix.scm and unix.o to be loaded into the interpreter (unix.o has to be linked with the interpreter on platforms that do not support dynamic loading of object files). In addition, the record extension is automatically loaded if it is not yet present. The record extension is documented in a separate reference manual.
Loading the UNIX extension causes the features unix and unix.o to be provided. Optionally, one or more of the following features (described below) may be provided by the extension to indicate that certain UNIX features are available:
unix:wait-options unix:wait-process unix:record-locks unix:file-locking unix:symlinks unix:reliable-signals