.\" /*
.\"  * Revision Control Information
.\"  *
.\"  * $Source: /vol/opua/opua2/sis/sis-1.1/common/src/sis/sis_lib/help/RCS/set.1,v $
.\"  * $Author: sis $
.\"  * $Revision: 1.4 $
.\"  * $Date: 1992/05/06 19:04:01 $
.\"  *
.\"
.XX
set [name] [value]
.X1
unset name ...
.PP
A variable environment is maintained by the command interpreter.
The \fBset\fR command sets a variable to a particular value, and the
\fBunset\fR command removes the definition of a variable.
If \fBset\fR is given no arguments, it prints the definition of all variables.
.PP
Different commands use environment information for different purposes.
The command interpreter makes use of the following:
.TP 8
.B autoexec
Defines a command string to be automatically executed after every command
processed by the command interpreter.
This is useful for things like timing
commands, or tracing the progress of optimization.
.TP 8
.B sisout
Standard output (normally stdout) can be re-directed to a file
by setting the variable sisout.
.TP 8
.B siserr
Standard error (normally stderr) can be re-directed to a file
by setting the variable siserr.
.TP 8
.B history
Each valid command entered at the prompt can be echoed to a file
by setting the variable history.
.TP 8
.B history_char
By default the character `%' is used to do the history substitution
inside sis. This can be changed by setting the variable \fBhistory_char\fR.
.TP 8
.B shell_char
By default the character `!' is used to do invoke shell commands from
inside sis.  This can be changed by setting the variable \fBshell_char\fR.
\fI In order to switch the interpretation of shell_char and history_char it is
neccessary to first set history_char and then the shell_char. Alternately,
you may escape the current history char by preceeding it with
a `\' while setting the shell_char. In addition none of them can be set 
to a `#' which is reserved for comments.\fR
.TP 8
.B filec
Setting this variable enables the user to use "file-completion" like in 
the C-shell. An ESC causes the current line to be extended to its unique 
completion. A CTRL-d generates a list of the possible extensions.
.TP 8
.B open_path
\fBopen_path\fR (in analogy to the shell-variable PATH) is a list of
colon-separated strings giving directories to be searched whenever
a file is opened for read.  Typically the current directory (.) is
first in this list.  The standard system 
library (typically $SIS/sis_lib) is always implicitly appended 
to the current path.
This provides a convenient short-hand
mechanism for reaching standard library files.
.TP 8
.B prompt
defines the prompt string. If the prompt string contains a `%'(or whatever
the history_char has been set to using the set command), the `%'
will be replaced whenever the prompt is printed by the current event number.
