SLSH
Section: (1)
Updated: 14 September 2014
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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");
#ifexists rline_up_hist_search
% Map the up/down arrow to the history search mechanism
rline_setkey (&rline_up_hist_search, "\e[A");
rline_setkey (&rline_down_hist_search, "\e[B");
#endif
#ifexists rline_edit_history
rline_setkey (&rline_edit_history, "^Kj");
#endif
% 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 <www.jedsoft.org>.
The interactive mode was provided by Mike Noble. 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 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
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- OPTIONS
-
- INITIALIZATION
-
- LOADING FILES
-
- INTERACTIVE MODE
-
- READLINE HISTORY MECHANISM
-
- MISCELLANEOUS SCRIPTS
-
- AUTHOR
-
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