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LEFTY(1)		    General Commands Manual		      LEFTY(1)

       lefty - A Programmable Graphics Editor

       lefty [ options ] [ file	]

       lefty is	a two-view graphics editor for technical pictures. This	editor
       has no hardwired	knowledge about	specific picture  layouts  or  editing
       operations.  Each picture is described by a program that	contains func-
       tions to	draw the picture and functions to perform  editing  operations
       that  are appropriate for the specific picture. Primitive user actions,
       like mouse and keyboard events, are also	bound  to  functions  in  this
       program.	 Besides  the graphical	view of	the picture itself, the	editor
       presents	a textual view of the program that describes the picture. Pro-
       grammability  and  the  two-view	interface allow	the editor to handle a
       variety of pictures, but	are particularly useful	for pictures  used  in
       technical contexts, e.g., graphs	and trees. Also, lefty can communicate
       with other processes. This feature allows it to use existing  tools  to
       compute	specific  picture layouts and allows external processes	to use
       the editor as a front end to display their data structures graphically.

       The file	name is	optional. It may be -, for reading from	 standard  in-
       put.  lefty uses	two environment	variables, LEFTYPATH and LEFTYOPTIONS.
       LEFTYPATH is a colon separated list of directories. When	lefty tries to
       open  a	file,  it searches that	path for the file. When	lefty tries to
       start up	another	process, it searches LEFTYPATH first, then  the	 stan-
       dard  PATH variable.  LEFTYOPTIONS can be used to set specific options.
       Options specified on the	command	line override options set through this

       -x     Instructs	the editor to exit after processing file.

       -e <expression>
	      <expression> is parsed and executed.

       -el <num>
	      Set  error  reporting  level.  The  default value	is 0.  0 never
	      prints any messages.  1 prints severe errors, such as trying  to
	      return  from  a  non function.  2	is the most useful: it reports
	      function calls that cannot be executed, either because there  is
	      no  function,  or	 because of argument mismatches.  3 also warns
	      about bad	variable names.	 4,5 warn about	 expressions  that  do
	      not  return  a value. Only level 1 messages are real errors. The
	      rest arise from legal lefty statements, but  may	be  caused  by
	      some logic errors.

       -sd <num>
	      Specifies	 how  much of the stack	to show, when an error message
	      is to be printed.	The default value is 2.	 With 0,  no  part  of
	      the stack	is shown. With 1, only the top stack frame is printed.
	      With 2, the full stack is	printed.

       -sb <num>
	      Specifies	how much of each function in the stack to  show,  when
	      an error message is to be	printed. The default value is 2.  With
	      0, no part of the	function is  shown.  With  1,  only  the  line
	      around  the  error is printed. With 2, the full function body is

       -df <string>
	      Sets the default font. This font is used	whenever  a  requested
	      font  cannot  be	found.	The  string must be a legal X font. If
	      string is	'', lefty will draw small boxes	instead	of text.

       -ps <file>
	      Specifies	a default file name for	postscript files. This name is
	      used when	no name	is specified in	the createwidget call. The de-
	      fault file name is

       -V     Prints the version.

       -?     Prints the usage and exits.

       lefty user guide.



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