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A Unix shell embedded into Scheme, with access to all Posix calls Reviewed by: max Submitted by: cracauer@cons.org "Martin Cracauer"
85 lines
3.5 KiB
Plaintext
85 lines
3.5 KiB
Plaintext
Scsh is a Unix shell in that is has significant syntax entensions to
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make writing Unix shell scripts easy (constructing pipelines, setting
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I/O redirection, conditional execution etc.). It also offers access to
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lower-level functionality like all Posix system calls, TCP/IP sockets
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and a full-featured regular expression library. All this is embedded
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into a general-purpose programming language with proper handling of
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quoting, real data types and extensive, syntactically clean control
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constructs.
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Scsh is also a full implementation of R4RS Scheme with some
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non-standard behaviour (required for scripting) that shouldn't be a
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problem in practice. As a result, a wide varity of exsting Scheme code
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can be used.
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Offered functionality:
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- Scheme special forms to work with Unix commands and command chains
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- the ability to be used to write self-identifying scripts with
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'#!/usr/local/bin/scsh' as the first line.
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- all Posix system calls including signals, tty and time handling
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- regular expressions, uses the same C library as *BSD, returns a
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proper structure describing the matches and/or matched substrings.
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- delimited strings, awk-like record/field processing
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- several socket layers
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- A foreign function interface to use other C code, including a tool
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(cig) to automate integration process.
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- elisp code to run it as a subprocess under emacs
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- On the Scheme side: a module system, basic thread support, optional
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static linker (compiles images to C, then into an executable).
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The underlying Scheme implementation is a virtual machine for compact
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byte code.
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Installed Items:
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----------------
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Main program name(s): "scsh"
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Manpage(s): scsh(1)
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Info files: <none>
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Other documentation: lib/scsh/doc/ (also linked to share/doc/scsh)
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Learning entry point: lib/scsh/doc/scsh-paper.ps or
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http://www-swiss.ai.mit.edu/scsh/
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General Notes:
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--------------
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Changing ${PREFIX} to something other than /usr/local works
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flawlessly, as far as scsh itself is concerned (that means: it will
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run and find everythings it needs). You will have to change the
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initial "#!/usr/local/bin/scsh" line when running shell scripts, of
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course. An additional problem is the location of optional packages
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like slib, these are still expected to be in /usr/local. I looked
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into the sources and all the hardcoded /usr/local I found are in files
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that are installed sourcecode form when scsh is installed
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(i.e. slib-init.scm).
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To load slib, install slib into /usr/local/lib/slib and run
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(load "slib-init.scm")
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in scsh. It requires no additional setup (paths or such).
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The emacs interface is in the original distribution in emacs/. For
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documentation see doc/user-quide.txt.
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Differences between FreeBSD port and generic scsh release:
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----------------------------------------------------------
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1) When hitting C-d (end-of-file), scsh asks 100 times for
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confirmation. I changed the default to do this just once. See constant
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*y-or-n-eof-count* in scsh/rw.scm to change it.
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2) The original scsh sends a mail to the scsh authors everytime you
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make the package. The FreeBSD port doesn't. The authors of scsh would
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appreciate it if you do a `(cd work/scsh-0.4.4 && make .notify)` after
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you build this package.
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3) A symbolic link ${PREFIX}/share/doc/scsh to the documentation is
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created.
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4) Some basic description text files from the distribution base dir
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are copied to lib/doc. The emacs directory is copied into
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lib/scsh/emacs. scsh's default is not to install these files.
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5) Some /usr/tmp -> /var/tmp
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FreeBSD port provided by Martin Cracauer <cracauer@cons.org>
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