 
   July 1, 1994                                                        SIS(1)
 
   set [name] [value]
   unset name ...
 
     A variable environment is maintained by the command interpreter.  The
     set command sets a variable to a particular value, and the unset command
     removes the definition of a variable.  If set is given no arguments, it
     prints the definition of all variables.
 
     Different commands use environment information for different purposes.
     The command interpreter makes use of the following:
 
     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.
 
     sisout  Standard output (normally stdout) can be re-directed to a file
             by setting the variable sisout.
 
     siserr  Standard error (normally stderr) can be re-directed to a file by
             setting the variable siserr.
 
     history Each valid command entered at the prompt can be echoed to a file
             by setting the variable history.
 
     history_char
             By default the character `%' is used to do the history substitu-
             tion inside sis. This can be changed by setting the variable
             history_char.
 
     shell_char
             By default the character `!' is used to do invoke shell commands
             from inside sis.  This can be changed by setting the variable
             shell_char.
              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.
 
     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.
 
     open_path
             open_path (in analogy to the shell-variable PATH) is a list of
             colon-separated strings giving directories to be searched when-
             ever a file is opened for read.  Typically the current directory
             (.) is first in this list.  The standard system library (typi-
             cally $SIS/sis_lib) is always implicitly appended to the current
 
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   SIS(1)                                                        July 1, 1994
 
             path.  This provides a convenient short-hand mechanism for
             reaching standard library files.
 
     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.
 
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