SLSH(1)                                                                SLSH(1)



NAME
       slsh - Interpreter for S-Lang scripts

SYNOPSIS
       slsh [ --help ] [ --version ] [ -g ] [ -n ] [ --init file ] [ --no-
       readline ] [ -e string ] [ -i ] [ -q, --quiet ] [ -t ] [ -v ] [
       -|script-file args... ]


DESCRIPTION
       slsh is a simple program for interpreting S-Lang scripts.  It supports
       dynamic loading of S-Lang modules and includes a readline interface for
       interactive use.

OPTIONS
       --help Show a summary of options

       --version
              Show slsh version information

       -g     Compile with debugging code, tracebacks, etc

       -n     Don't load the personal initialization file

       --init file
              Use this file instead of ~/.slshrc

       --no-readline
              Do not use a readline interface for the interactive mode

       -e string
              Execute ``string'' as S-Lang code.

       -i     Force interactive mode.  Normally slsh will go into interactive
              mode if both stdin and stdout are attached to a terminal.

       -q, --quiet
              Startup quietly by not printing the version and copyright
              information.

       -t     Normally, slsh will call slsh_main if it is defined.  This
              option prevents that from happening making it useful for
              checking for syntax error.

       -v     Show verbose loading messages.  This is useful for seeing what
              files are being loaded.

INITIALIZATION
       Upon startup, the program will try to load slsh.rc as follows. If
       either SLSH_CONF_DIR or SLSH_LIB_DIR environment variables exist, then
       slsh will look look in the corresponding directories for slsh.rc.
       Otherwise it will look in:

       $(prefix)/etc/   (as specified in the Makefile)

       /usr/local/etc/

       /usr/local/etc/slsh/

       /etc/

       /etc/slsh/

       The slsh.rc file may load other files from slsh's library directory in
       the manner described below.

       Once slsh.rc has been loaded, slsh will load $HOME/.slshrc if present.
       Finally, it will load the script specified on the command line.  If the
       name of the script is -, then it will be read from stdin.  If the
       script name is not present, or a string to execute was not specified
       using the -e option, then slsh will go into interactive mode and read
       input from the terminal.  If the script is present and defines a
       function called slsh_main, that function will be called.

LOADING FILES
       When a script loads a file via the built-in evalfile function or the
       require function (autoloaded by slsh.rc), the file is searched for
       along the SLSH_PATH as specified in the Makefile.  An alternate path
       may be specified by the SLSH_PATH environment variable.

       The search path may be queried and set during run time via the
       get_slang_load_path and set_slang_load_path functions, e.g.,

          set_slang_load_path ("/home/bill/lib/slsh:/usr/share/slsh");

INTERACTIVE MODE
       When slsh is invoked without a script or is given the -i command line
       argument, it will go into into interactive mode.  In this mode, the
       user will be prompted for input.  The program will leave this mode and
       exit if it sees an EOF (Ctrl-D) or the user exits by issuing the quit
       command.

       If an uncaught exception occurs during execution of a command, the
       error message will be shown and the user will be prompted for more
       input.

       Any objects left on the stack after a command will be printed and the
       stack cleared.  This makes interactive mode useful as a calculator,
       e.g.,

            slsh> 3*10;
            30
            slsh> x = [1:20];
            slsh> sum (sin(x)-cos(x));
            0.458613
            slsh> quit;
       Note that in this mode, variables are automatically declared.

       The interactive mode also supports command logging.  Logging is enabled
       by the start_log function.  The stop_log function will turn off
       logging.  The default file where logging information will be written is
       slsh.log.  An alternative may be specified as an optional argument to
       the start_log function:

            slsh> start_log;
            Logging input to slsh.log
       .
       .
            slsh> stop_log;
            slsh> start_log("foo.log");
            Logging input to foo.log
       .
       .
            slsh> stop_log;
            slsh> start_log;
            Logging input to foo.log

       Similarly, the save_input function may be used to save the previous
       input to a specified file:

            slsh> save_input;
            Input saved to slsh.log
            slsh> save_input ("foo.log");
            Input saved to foo.log

       As the above examples indicate, lines must end in a semicolon.  This is
       a basic feature of the language and permits commands to span multiple
       lines, e.g.,

            slsh> x = [
                   1,2,3,
                   4,5,6];
            slsh> sum(x);
       For convenience some users prefer that commands be automatically
       terminated with a semicolon.  To have a semicolon silently appended to
       the end of an input line, put the following in $HOME/.slshrc file:

           #ifdef __INTERACTIVE__
           slsh_append_semicolon (1);
           #endif

       The interactive mode also supports shell escapes.  To pass a command to
       the shell, prefix it with !, e.g.,

           slsh> !pwd
           /grandpa/d1/src/slang2/slsh
           slsh> !cd doc/tm
           slsh> !pwd
           /grandpa/d1/src/slang2/slsh/doc/tm

       Finally, the interactive mode supports a help and apropos function:

           slsh> apropos list
           apropos list ==>
           List_Type
           list_append
           list_delete
       .
       .
           slsh> help list_append
           list_append

            SYNOPSIS
              Append an object to a list

            USAGE
              list_append (List_Type, object, Int_Type nth)
       .
       .
       For convenience, the help and apropos functions do not require the
       syntactic constraints of the other functions.

READLINE HISTORY MECHANISM
       By default, slsh is built to use the S-Lang readline interface, which
       includes a customizable command completion and a history mechanism.
       When slsh (or any S-Lang application that makes use of this feature)
       starts in interactive mode, it will look for a file in the user's home
       directory called .slrlinerc and load it if present.  This file allows
       the user to customize the readline interface and enable the history to
       be saved between sessions.  As an example, here is a version of the
       author's .slrlinerc file:

            % Load some basic functions that implement the history mechanism
            () = evalfile ("rline/slrline.rc");
            % The name of the history file -- expands to .slsh_hist for slsh
            RLine_History_File = "$HOME/.${name}_hist";

            % Some addition keybindings.  Some of these functions are defined
            % in rline/editfuns.sl, loaded by rline/slrline.rc
            rline_unsetkey ("^K");
            rline_setkey ("bol",   "^B");
            rline_setkey ("eol",   "^E");
            rline_setkey (&rline_kill_eol,  "^L");
            rline_setkey (&rline_set_mark,  "^K^B");
            rline_setkey (&rline_copy_region, "^Kk");
            rline_setkey (&rline_kill_region, "^K^V");
            rline_setkey (&rline_yank,  "^K^P");
            rline_setkey ("redraw",   "^R");

            % Add a new function
            private define double_line ()
            {
               variable p = rline_get_point ();
               variable line = rline_get_line ();
               rline_eol ();
               variable pend = rline_get_point ();
               rline_ins (line);
               rline_set_point (pend + p);
            }
           rline_setkey (&double_line,  "^K^L");

MISCELLANEOUS SCRIPTS
       Several useful example scripts are located in
       $prefix/share/slsh/scripts/, where $prefix represents the slsh
       installation prefix (/usr, /usr/local,...).  These scripts include:

       sldb   A script that runs the S-Lang debugger.

       jpegsize
              Reports the size of a jpeg file.

       svnsh  A shell for browsing an SVN repository.

AUTHOR
       The principal author of slsh is John E. Davis <jed@jedsoft.org>.  The
       interactive mode was provided by Mike Noble <mnoble@space.mit.edu>.
       The S-Lang library upon which slsh is based is primarily the work of
       John E. Davis with help from many others.

       This manual page was originally written by Rafael Laboissiere
       <rafael@debian.org> for the Debian system (but may be used by others).

       Permission is granted to copy, distribute and/or modify this document
       under the terms of the GNU General Public License, Version 2 any later
       version published by the Free Software Foundation.

       On Debian systems, the complete text of the GNU General Public License
       can be found in /usr/share/common-licenses/GPL



                                02 August 2009                         SLSH(1)
