Scsh 0.6.1 Release notes -*- outline -*- We are pleased to release scsh version 0.6.1. This release fixes most of the known bugs of the previous version. Users of version 0.6.0 are strongly encouraged to upgrade to the new version. The text below gives a general description of scsh, instructions for obtaining it, pointers to discussion forums, and a description of the new features in release 0.6.1. (Emacs should display this document is in outline mode. Say c-h m for instructions on how to move through it by sections (e.g., c-c c-n, c-c c-p).) * Contents ========== What is scsh Scsh as a scripting language Scsh as a systems-programming language Scsh is a portable programming environment Obtaining and installing scsh Getting in touch The World-Wide What? New in this release API changes Bugfixes New in 0.6.0 Thanks * What is scsh ============== Scsh is a broad-spectrum systems-programming environment for Unix embedded in R5RS Scheme. It has an open-source copyright, and runs on most major Unix systems. ** Scsh as a scripting language ------------------------------- Scsh has a high-level process notation for doing shell-script like tasks: running programs, establishing pipelines and I/O redirection. For example, the shell pipeline gunzip < paper.tex.gz | detex | spell | lpr -Ppulp & would be written in scsh as (& (| (gunzip) (detex) (spell) (lpr -Ppulp)) ; Background a pipeline (< paper.tex.gz)) ; with this redirection Scsh embeds this process notation within a full Scheme implementation. 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. Scripts can be written as standalone Scheme source files, with a leading #!/usr/local/bin/scsh -s trigger line. ** Scsh as a systems-programming language ----------------------------------------- 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. "Complete 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. In brief, you can now write Unix systems programs in Scheme instead of C. For example, we have implemented an extensible HTTP server at MIT entirely in scsh. As important as full access to the OS is the manner in which it is provided. Scsh integrates the OS support into Scheme in a manner which respects the general structure of the language. The details of the design are discussed in a joint MIT Lab for Computer Science/University of Hong Kong technical report, "A Scheme Shell," also to appear in a revised format in the "Journal of Lisp and Symbolic Computation." This paper is also available by ftp: ftp://ftp.scsh.net/pub/scsh/papers/scsh-paper.ps ** Scsh is a portable programming environment --------------------------------------------- Scsh is designed for portability. It is implemented on top of Scheme 48, a byte-code-interpreter Scheme implementation. The Scheme 48 virtual machine can be compiled on any system with a C compiler; the rest of Scheme 48 is machine-independent across 32-bit processors. Scsh's OS interface is also quite portable, providing a consistent interface across different Unix platforms. We currently have scsh implementations for: AIX BSD/OS CXUX FreeBSD HP-UX IRIX Linux NetBSD Solaris SunOS Ultrix Win32 Darwin/Mac OS X Scsh code should run without change across these systems. Porting to new platforms is usually not difficult. * Obtaining and installing scsh =============================== You can get a copy of scsh via anonymous ftp, from ftp://ftp.scsh.net/pub/scsh/scsh.tar.gz The tar file includes a detailed manual and a paper describing the design of the system. For the lazily curious, we also have the manual separately available as ftp://ftp.scsh.net/pub/scsh/0.6/scsh-manual.ps Just click 'n view. You *should* be able to build scsh on the standard platforms with exactly five commands: gunzip, tar, cd, ./configure, and make. The configure script figures out the special flags and switches needed to make the build work (thanks to the GNU project for the autoconfig tool that makes this possible). After doing the make, you can start up a Scheme shell and try it out by saying ./go See the manual for full details on the command-line switches. If it's harder than this, and your system is standard, we'd like to know about it. * Getting in touch ================== There are two main ways to join in scsh-related discussion: the mailing-list scsh@zurich.ai.mit.edu and the netnews group comp.lang.scheme.scsh These two forums should be equivalent, being bi-directionally gatewayed at MIT, but due to technical problems it's better to read them both. Bugs can be reported to scsh-bugs@zurich.ai.mit.edu or via the Scsh project's bugs section on SourceForge: http://sourceforge.net/projects/scsh/ If you do not netnews hierarchy, or wish to join the mailing list for other reasons, send mail to scsh-request@zurich.ai.mit.edu * The World-Wide What? ====================== We even have one of those dot-com cyberweb things: http://www.scsh.net We manage the project using SourceForge: http://sourceforge.net/projects/scsh/ * New in this release ===================== ** API changes For sre's, BOW, EOW, WORD, and WORD+ (which were already unsupported in 0.6.0 on most platforms) are gone for good. ** Bugfixes Most of the known bugs of version 0.6.0 have been fixed, many thanks for the precise reports! See the project page on SourceForge for a list of the remaining known bugs. Here is a brief overview of the fixes: - GC_PROTECT'ed the necessary variables (specifically, where >1 arg to a function 'may GC') (Thanks to Steven Jenkins for dealing with this) - Fixed various race conditons in the signal handling and process reaping code - Fixed bug in set-process-group - If $HOME is unset, consult (user-info (user-uid)) for the value of home-directory - Fix external-call-from-callback problem leading to spurious gc-protection-mismatch exceptions. - Let s48-do-gc return 0 so the PreScheme compiler will emit the correct signature of the function. - scsh/linux/tty-consts.scm: num-ttychars seems to be 32 not 19. - scsh/top.scm: Return 0 exit status for -c and -e. - *.c: Replaced // comments. - scsh/syslog1.c: Remove LOG_LPR from list of syslog levels. - scsh/network1.c: Pass SYSCALL argument to ERRNO-ERROR. - scsh/syscalls1.c: Disable timer interrupts before execve - scsh/network.scm: Correct name extraction in bind-socket - Added export for with-error-output-port - Install HTML version of manual under $(libdir) - ./configure is more rebost wrt $(srcdir) - Fixed installation of the S48 manual - Replaced several /tmp by /var/tmp - Catch EISDIR in delete-filesys-object - flush-all-ports is now non-blocking * New in 0.6.0 ============== ** Scsh is now based on Scheme 48 0.53 With the move from Scheme 48 version 0.36 to version 0.53 in this release the underlying system received a massive update. The most significant changes include: User level threads Advanced garbage collector Improved foreign function interface to C The most significant change for Scsh users is the addition of a user-level thread system. Scsh provides various features to deal with this new power in a system programming environment: An event based interface to interrupts, thread local process state and thread-safe system calls. ** A manual for Scheme 48 has been included Richard Kelsey, the author of Scheme 48, has graciously allowed us to retrofit the current Scheme 48 manual for inclusion in this scsh release. ** Interfaces to dot-locking, crypt and syslog Scsh now provides advisory file locking via the dot-locking scheme and a direct binding to the crypt function. Furthermore we added a complete, system-independent and thread-safe interface to syslog. ** API changes Some features of the previous releases are currently not supported as we did not have the time to implement them. Please tell us, if you can't get along without them. Here is a listing of these currently dereleased features: select select! ODBC support bufpol/line The following procedures received new names in this release: sleep (now process-sleep) sleep-until (now process-sleep-until) network-info, service-info and protocol-info now return #f on non-success. The default directory for creating temporary files has changed: It's now the value of $TMPDIR if set and /var/tmp otherwise. The nth procedure is still there but is now officially obsolete. It will go away in a future release. ** HTML version of the manual There is now a HTML version of the scsh manual generated by tex2page * Thanks ======== We would like to thank the members of local-resistance cells for the Underground everywhere for bug reports, bug fixes, design review and comments that were incorporated into this release. We really appreciate their help, particularly in the task of porting scsh to new platforms. Friedrich Dominicus Jay Nietling Tim Bradshaw Robert Brown Eric Marsden Paul Emsley Pawel Turnau Hannu Koivisto Andy Gaynor Francisco Vides Fernandez Tim Burgess Brian Denheyer Harvey Stein Eric Hilsdale Andreas Bernauer Reini Urban Peter Biber Roland Weiss Richard Günther Dirk Staneker Johannes Hirche Brought to you by the Scheme Underground. Go forth and write elegant systems programs. -Olin Shivers, Brian Carlstrom, Martin Gasbichler & Mike Sperber