---
name: "scm"
section: "1"
platform: "linux"
package: "scm"
version: "5f4-3"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/scm"
---

# scm(1)

a Scheme Language Interpreter

## NAME

scm - a Scheme Language Interpreter

## SYNOPSIS

**scm** \[-a *kbytes* \] \[-muvqib\] \[--version\] \[--help\]\
 \[\[-\]-no-init-file\] \[--no-symbol-case-fold\]\
 \[-p *int* \] \[-r *feature* \] \[-h *feature* \]\
 \[-d *filename* \] \[-f *filename* \] \[-l *filename* \]\
 \[-c *expression* \] \[-e *expression* \] \[-o *dumpname* \]\
 \[-- \| - \| -s\] \[ *filename* \] \[ *arguments ...* \]\

## DESCRIPTION

*Scm* is a Scheme interpreter.

Upon startup *scm* loads the file specified by by the environment variable SCM\_INIT\_PATH or by the parameter IMPLINIT in the makefile (or scmfig.h) if SCM\_INIT\_PATH is not defined.  The makefiles attempt to set IMPLINIT to "Init.scm" in the source directory.

Unless the option *-no-init-file* or *--no-init-file* occurs in the command line or if *scm* is being invoked as a script, "Init.scm" checks to see if there is file "ScmInit.scm" in the path specified by the environment variable HOME (or in the current directory if HOME is undefined).  If it finds such a file, then it is loaded.

"Init.scm" then looks for command input from one of three sources: From an option on the command line, from a file named on the command line, or from standard input.

## OPTIONS

The options are processed in the order specified on the command line.

- **-a***kbytes*

  specifies that *scm* should allocate an initial heapsize of *kbytes.* This option, if present, must be the first on the command line.

- **--no-init-file**

  Inhibits the loading of "ScmInit.scm" as described above.

- **--no-symbol-case-fold**

  Symbol (and identifier) names are case-sensitive.

- **-e***expression*

  - **-c***expression*

  specifies that the scheme expression *expression* is to be evaluated.  These options are inspired by *perl* and *sh* respectively. On Amiga systems the entire option and argument need to be enclosed in quotes.  For instance "-e(newline)".

- **-r***feature*

  requires *feature.* This will load a file from SLIB if that *feature* is not already supported.  If *feature* is 2, 3, 4, or 5 *scm* will require the features necessary to support R2RS, R3RS, R4RS, or R5RS, respectively.

- **-h***feature*

  provides *feature.*

- **-l***filename*

  - **-f***filename*

  loads *filename.* *Scm* will load the first (unoptioned) file named on the command line if no -c, -e, -f, -l, or -s option precedes it.

- **-d***filename*

  opens (read-only) the extended relational database *filename.* If *filename* contains initialization code, it will be run when the database is opened.

- **-o***dumpname*

  saves the current SCM session as the executable program  *dumpname.* This option works only in SCM builds supporting  **dump.**

  If options appear on the command line after  *-o dumpname,* then the saved session will continue with processing those options when it is invoked.  Otherwise the (new) command line is processed as usual when the saved image is invoked.

- **-p***level*

  sets the prolixity (verboseness) to *level.* This is the same as the *scm* command (verbose *level* ).

- **-v**

  (verbose mode) specifies that *scm* will print prompts, evaluation times, notice of loading files, and garbage collection statistics.  This is the same as *-p3.*

- **-q**

  (quiet mode) specifies that *scm* will print no extra information.  This is the same as *-p0.*

- **-m**

  specifies that subsequent loads, evaluations, and user interactions will be with R4RS macro capability.  To use a specific R4RS macro implementation from SLIB (instead of SLIB's default) put *-r macropackage* before *-m* on the command line.

- **-u**

  specifies that subsequent loads, evaluations, and user interactions will be without R4RS macro capability.  R4RS macro capability can be restored by a subsequent *-m* on the command line or from Scheme code.

- **-i**

  specifies that *scm* should run interactively.  That means that *scm* will not terminate until the *(quit)* or *(exit)* command is given, even if there are errors.  It also sets the prolixity level to 2 if it is less than 2.  This will print prompts, evaluation times, and notice of loading files.  The prolixity level can be set by subsequent options.  If *scm* is started from a tty, it will assume that it should be interactive unless given a subsequent *-b* option.

- **-b**

  specifies that *scm* should run non-interactively.  That means that *scm* will terminate after processing the command line or if there are errors.

- **-s**

  specifies, by analogy with *sh,* that further options are to be treated as program arguments.

- **-**

  **--** specifies that there are no more options on the command line.

## ENVIRONMENT VARIABLES

- **SCM\_INIT\_PATH**

  is the pathname where *scm* will look for its initialization code.  The default is the file "Init.scm" in the source directory.

- **SCHEME\_LIBRARY\_PATH**

  is the SLIB Scheme library directory.

- **HOME**

  is the directory where "Init.scm" will look for the user initialization file "ScmInit.scm".

## SCHEME VARIABLES

- **\*argv\***

  contains the list of arguments to the program. *\*argv\** can change during argument processing.  This list is suitable for use as an argument to SLIB *getopt.*

- **\*R4RS-macro\***

  controls whether loading and interaction support R4RS macros.  Define this in "ScmInit.scm" or files specified on the command line.  This can be overridden by subsequent -m and -u options.

- **\*interactive\***

  controls interactivity as explained for the -i and -b options.  Define this in "ScmInit.scm" or files specified on the command line.  This can be overridden by subsequent -i and -b options.

## EXAMPLES

- % scm foo.scm arg1 arg2 arg3

  Load and execute the contents of foo.scm.  Parameters arg1 arg2 and arg3 are stored in the global list \*argv\*.

- % scm -f foo.scm arg1 arg2 arg3

  The same.

- % scm -s foo.scm arg1 arg2

  Set \*argv\* to ("foo.scm" "arg1" "arg2") and enter interactive session.

- % scm -e '(display (list-ref \*argv\* \*optind\*))' bar

  Print \`\`bar''

- % scm -rpretty-print -r format -i

  Load pretty-print and format and enter interactive mode.

- % scm -r5

  Load dynamic-wind, values, and R4RS macros and enter interactive (with macros) mode.

- % scm -r5 -r4

  Like above but rev4-optional-procedures are also loaded.

## FEATURES

Runs under Amiga, Atari-ST, MacOS, MS-DOS, OS/2, NOS/VE, Unicos, VMS, Unix and similar systems.  Support for ASCII and EBCDIC character sets.

Conforms to Revised^5 Report on the Algorithmic Language Scheme and the IEEE P1178 specification.

Support for SICP, R2RS, R3RS, and R4RS scheme code.

Many Common Lisp functions: logand, logor, logxor, lognot, ash, logcount, integer-length, bit-extract, defmacro, macroexpand, macroexpand1, gentemp, defvar, force-output, software-type, get-decoded-time, get-internal-run-time, get-internal-real-time, delete-file, rename-file, copy-tree, acons, and eval.

Char-code-limit, most-positive-fixnum, most-negative-fixnum, and internal-time-units-per-second constants.  \*Features\* and \*load-pathname\* variables.

Arrays and bit-vectors.  String ports and software emulation ports. I/O extensions providing most of ANSI C and POSIX.1 facilities.

User definable responses to interrupts and errors, Process-synchronization primitives, String regular expression matching, and the CURSES screen management package.

Available add-on packages including an interactive debugger, database, X-window graphics, BGI graphics, Motif, and Open-Windows packages.

A compiler (HOBBIT, available separately) and dynamic linking of compiled modules.

Setable levels of monitoring and timing information printed interactively (the \`verbose' function).  Restart, quit, and exec.

## FILES

- scm.texi

  Texinfo documentation of *scm* enhancements, internal representations, and how to extend or include *scm* in other programs.

## AUTHORS

Aubrey Jaffer (agj@alum.mit.edu)\
 Radey Shouman

## BUGS

## SEE ALSO

The SCM home-page:\
 http://people.csail.mit.edu/jaffer/SCM.html

The Scheme specifications for details on specific procedures (http://groups.csail.mit.edu/mac/ftpdir/scheme-reports) or

IEEE Std 1178-1990,\
 IEEE Standard for the Scheme Programming Language,\
 Institute of Electrical and Electronic Engineers, Inc.,\
 New York, NY, 1991

Brian Harvey and Matthew Wright\
 Simply Scheme: Introducing Computer Science\_\
 MIT Press, 1994 ISBN 0-262-08226-8

R. Kent Dybvig, The Scheme Programming Language,\
 Prentice-Hall Inc, Englewood Cliffs, New Jersey 07632, USA

H. Abelson, G. J. Sussman, and J. Sussman,\
 Structure and Interpretation of Computer Programs,\
 The MIT Press, Cambridge, Massachusetts, USA