A `scheme' interpreter designed for writing system programs

 Scsh has a high-level process notation for doing shell-script like
 tasks: running programs, establishing pipelines and I/O redirection.
 Scsh embeds this process notation within a full implementation of
 Scheme, a minimal and clean dialect of the Lisp programming language.
 The process notation is realized as a set of macro definitions, and
 is carefully designed to allow full integration with standard Scheme
 code. Scsh isn't Scheme-like; it is Scheme.
 .
 At the scripting level, scsh also has an Awk design, also implemented
 as a macro that can be embedded inside general Scheme code.
 .
 Scsh additionally provides the low-level access to the operating
 system normally associated with C. The current release provides full
 access to POSIX, plus important non-POSIX extensions, such as
 complete sockets support. "Full access to POSIX" means: fork, exec &
 wait, sockets, full read, write, open & close, seek & tell, complete
 file-system access, including stat, chmod/chgrp/chown, symlink, FIFO
 & directory access, tty & pty support, file locking, pipes, select,
 file-name pattern-matching, time & date, environment variables,
 signal handlers, and more.