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||General Commands Manual
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 functions 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. Programmability 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
The file name is optional. It may be -, for reading from standard input.
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 standard PATH variable.
LEFTYOPTIONS can be used to set specific options. Options specified on
the command line override options set through this variable.
- 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
- -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 printed.
- -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 default file
name is out.ps.
- Prints the version.
- Prints the usage and exits.
lefty user guide.