
  set - Set an environment variable
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   set [-h] [<name>] [<value>]
   
   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 current value of all variables.
   
   Command options:
   
   -h
          Print the command usage.
          
   <name>
          Variable name
          
   <value>
          Value to be assigned to the variable.
          
   Interpolation of variables is allowed when using the set command. The
   variables are referred to with the prefix of '$'. So for example, the
   following can be done to check the value of a set variable:
   NuSMV> set foo bar
   NuSMV> echo $foo
   bar
   The last line "bar" will the output produced by NuSMV.
   
   Variables can be extended by using the character ':' to concatenate
   values. For example :
   NuSMV> set foo bar
   NuSMV> set foo $foo:foobar
   NuSMV> echo $foo
   bar:foobar
   The variable foo is extended with the value foobar .
   
   Whitespace characters may be present within quotes. However, variable
   interpolation lays the restriction that the characters ':' and '/' may
   not be used within quotes. This is to allow for recursive
   interpolation. So for example, the following is allowed
   NuSMV> set "foo bar" this
   NuSMV> echo $"foo bar"
   this
   The last line will be the output produced by NuSMV.
   But in the following, the value of the variable foo/bar will not be
   interpreted correctly:
   
   NuSMV> set "foo/bar" this
   NuSMV> echo $"foo/bar"
   foo/bar
   If a variable is not set by the "set" command, then the variable is
   returned unchanged.
   
   Different commands use environment information for different purposes.
   The command interpreter makes use of the following parameters:
   
   _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.
          
   _open_path_
          "open_path" (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 $NuSMV_LIBRARY_PATH) is always implicitly
          appended to the current path. This provides a convenient
          short-hand mechanism for reaching standard library files.
          
   _nusmv_stderr _
          Standard error (normally stderr) can be re-directed to a file
          by setting the variable nusmv_stderr.
          
   _nusmv_stdout_
          Standard output (normally stdout) can be re-directed to a file
          by setting the variable nusmv_stdout.
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   Last updated on 990119 20h08
