Running MzScheme

The stand-alone version of MzScheme accepts a number of command-line flags. Under MacOS, a user can specify command-line flags by holding down the Command key while starting MzScheme, which provides a dialog for entering the command line. Dragging files onto the MzScheme icon in MacOS is equivalent to providing each file's name on the command line preceded by -f, so each file is loaded after MzScheme starts. When files are dragged onto MzScheme with the Command key pressed, the command line specified in the dialog is appended to the implicit command-line for loading the files.

MzScheme accepts the following flags:

• Startup file and expression flags:

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  -e expr : Evaluates expr after MzScheme starts.

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  -f file : Loads file after MzScheme starts.

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  -d file : Uses load/cd to load file after MzScheme starts.

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  -F : Loads each remaining argument as a file after MzScheme starts.

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  -D : Loads each remaining argument as a file using load/cd after MzScheme starts.

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  -l file : Loads the MzLib library file after MzScheme starts.

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  -L file collect : Loads the library file in the collection collect after MzScheme starts.

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  -r file or --script file : Use this flag for MzScheme-based scripts. It mutes the startup banner printout, suppresses the read-eval-print loop, and loads file after MzScheme starts. No argument after file is treated as a flag. The -r or --script flag is a shorthand for -fmv-.

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  -i file or --script-cd file : Same as -r file or --script file, except that the current directory is changed to file's directory before it is loaded. The -i or --script-cd flag is a shorthand for -dmv-.

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  -w or --awk : Loads the awk.ss library after MzScheme starts.

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  -k n m : Loads code embedded in the executable from file position n to m after MzScheme starts. This flag is useful for creating a stand-alone binary by appending code to the normal MzScheme executable. See PLT mzc: MzScheme Compiler Manual for more details.

• Initialization flags:

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  -x or --no-lib-path : Suppresses the initialization of current-library-collection-paths (as described in Chapter 15).

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  -q or --no-init-file : Suppresses loading the user's initialization file, as described below.

• Language setting flags:

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  -g or --case-sens : Creates an initial namespace where identifiers and symbols are case-sensitive.

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  -c or --esc-cont : Creates an initial namespace where call-with-current-continuation and call/cc capture escape continuations (like call/ec) instead of full continuations.

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  -s or --set-undef : Creates an initial namespace where set! will successfully mutate an undefined global variable (implicitly defining it).

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  -a or --no-auto-else : Creates an initial namespace where falling through all of the clauses in a cond or case expression raises the exn:else exception.

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  -n or --no-key : Creates an initial namespace where keywords are not enforced.

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  -y or --hash-percent-syntax : Creates an initial namespace that includes only the #% syntactic forms.

• Miscellaneous flags:

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  - : No argument following this flag is used as a flag.

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  -m or --mute-banner : Suppresses the startup banner text.

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  -v or --version : Suppresses the read-eval-print loop.

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  -h or --help : Shows information about MzScheme's command-line flags and then exits; ignoring other flags.

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  -p or --persistent : Catches the SIGDANGER (low page space) signal and ignores it (AIX only).

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  -Rfile or --restore file : Restores a saved image (see section 14.8). Extra arguments after file are returned as a vector of strings to the continuation of the write-image-to-file call that created the image.

Extra arguments following the last flag are put into the Scheme global variable argv as a vector of strings. The name used to start MzScheme is put into the global variable program as a string.

Multiple single-letter flags (the ones preceded by a single dash) can be collapsed into a single flag by concatenating the letters, as long as the the first flag is not -. The arguments for each flag are placed after the collapsed flags (in the order of the flags). For example,

  -vfme file expr 

  -v -f file -m -e expr 

The current-library-collection-paths parameter is initialized (as described in Chapter 15) before any expression or file is evaluated or loaded, unless the -x or --no-lib-path flag is specified.

Unless the -q or --no-init-file flag is specified, a user initialization file is loaded after current-library-collection-paths parameter is initialized and before any other expression or file is evaluated or loaded. The path to the user initialization file is obtained from MzScheme's find-system-path procedure using 'init-file.

Expressions and files are evaluated and loaded in order that they are provided on the command line. If an error occurs, the remaining expressions and files are skipped. The thread that loads the files and evaluates the expressions is the main thread. When the main thread terminates (or is killed), the MzScheme process exits.

After the command-line files and expressions are loaded and evaluated, the main thread calls , unless the -v, --version, -r, --script, -i, --script-cd flag is specified.

The exit status for the MzScheme process indicates an error if an error occurs evaluating or loading a command-line expression or file and is not called afterwards, or if the default exit handler is called with an exact integer between 1 and 255.