table of contents
GRAP(1) | General Commands Manual | GRAP(1) |
NAME¶
grap
—
Kernighan and Bentley's language for typesetting
graphs
SYNOPSIS¶
grap |
[-d
defines_file-D -l -M
include path-R -r -v -u -C -c -h filename ... ] |
DESCRIPTION¶
grap
is an implementation of Kernighan and
Bentley's language for typesetting graphs, as described in ``Grap-A Language
for Typesetting Graphs, Tutorial and User Manual,'' by Jon L. Bentley and
Brian W. Kernighan, revised May 1991, which is the primary source for
information on how to use grap
. As of this
writing, it is available electronically at
http://www.kohala.com/start/troff/cstr114.ps
.
Additional documentation and examples, packaged with
grap
, may have been installed locally as
well. If available, paths to them can be displayed using
grap
-h
or grap
-v
(or
grap
--help
/
grap
--version
)
This version is a black box implementation of
grap
, and some inconsistencies are to be
expected. The remainder of this manual page will briefly outline the
grap
language as implemented here.
grap
is a pic(1)
pre-processor. It takes commands embedded in a
troff(1) source file which are surrounded by
.G1
and
.G2
macros, and rewrites them into
pic commands to display the graph. Other lines
are copied. Output is always to the standard output, which is usually
redirected. Input is from the given
filenames, which are
read in order. A filename of
-
is the standard input. If no
filenames are given,
input is read from the standard input.
Because grap
is a
pic preprocessor, and GNU
pic will output TeX, it is possible to use
grap
with TeX.
The -d
option specifies a file of macro
definitions to be read at startup, and defaults to
/usr/share/grap/grap.defines . The -D
option inhibits the reading of any initial macros file (the
-l
flag is a synonym for
-D
, though I do not remember why). The
defines file can also be given using the
GRAP_DEFINES
environment variable. (See
below).
-v
prints the version information on the
standard output and exits. --version
is a
synonym for -v
.
-u
makes labels unaligned by default. This
version of grap
uses new features of GNU
pic to align the left and right labels with the
axes, that is that the left and right labels run at right angles to the text
of the paper. This may be useful in porting old
grap
programs.
-c
makes plot strings unclipped by default.
Some versions of grap
allow users to place
a string anywhere in the coordinate space, rather than only in the frame. By
default this version of grap
does not plot
any string centered outside the frame. -c
allows strings to be placed anywhere. See also the
clipped
and
unclipped
string modifiers described in the
plot
statement.
-M
is followed by a colon-separated list of
directories used to search for relative pathnames included via
copy
. The path is also used to locate the
defines file, so if the -d
changes the
defines file name to a relative name, it will be searched for in the path
given by -M
. The search path always
includes the current directory, and by default that directory is searched
last.
All numbers used internally by grap
are
double precision floating point values. Sometimes using floating point numbers
has unintended consequences. To help avoid these problems,
grap
can use two thresholds for comparison
of floating point numbers, set by -R
or
-r
. The
-R
flag sets coarse comparison mode, which
is suitable for most applications. If you are plotting small values –
less than 1e-6 or so – consider using
-r
which uses very fine comparisons between
numbers. You may also want to rescale your plotted values to be larger in
magnitude. The coarse comarisons are used by default.
To be precise, the value by which two numbers must differ for
grap
to consider them not equal is called
the comparison limit and the smallest non-zero number is called the minimum
value. The values a given version of grap
uses for these are included in the output of
-v
or
-h
.
All grap
commands are included between
.G1
and
.G2
macros, which are consumed by
grap
. The output contains
pic between
.PS
and
.PE
macros. Any arguments to the
.G1
macro in the input are arguments to the
.PS
macro in the output, so graphs can be
scaled just like pic diagrams. If
-C
is given, any macro beginning with .G1
or .G2 is treated as a .G1 or .G2 macro, for compatibility with old versions
of troff. Using -C
also forces pure troff
syntax on embedded font change commands when strings have the
size
attribute, and all strings to be
unclipped
.
The -h
flag prints a brief help message and
exits. --help
is a synonym for
-h
.
It is possible for someone to cause grap
to
fail by passing a bad format string and data to the
sprintf
command. If
grap
is integrated as part of the printing
system, this could conceivably provided a path to breaching security on the
machine. If you choose to use grap
as part
of a printing system run by the super-user, you should disable
sprintf
commands. This can be done by
calling grap
with the
-S
flag, setting the
GRAP_SAFER
environment variable, or
compiling with the GRAP_SAFER preprocessor symbol defined. (The GNU configure
script included with grap
will define that
preprocessor symbol if the --with-grap-safe
option is given.)
The grap
commands are sketched below. Refer
to Kernighan and Bentley's paper for the details.
New versions of groff(1) will invoke
grap
if
-G
is given.
Commands¶
Commands are separated from one another by newlines or semicolons (;).frame
[line_description
]
[ht
height | wid
width[
]
(
] ...top
|bottom
|left
|
right
)
line_descriptionframe
[ht
height | wid
widthline_description
]
[[
]
(
] ...top
|bottom
|left
|
right
)
line_descriptionThis describes how the axes for the graph are drawn. A
line_description is a
pic line description, e.g.,
dashed
0.5
, or the literal
solid
. It may also include a
color
keyword followed by the color to draw
the string in double quotes. Any color understood by the underlying groff
system can be used. Color can only be used under GNU pic, and is not available
in compatibility mode. Similarly, for pic implementations that understand
thickness
, that attribute may be used with
a real valued parameter. Thickness
is not
available in compatibility mode.
If the first line_description is given, the
frame is drawn with that style. The default is solid
.
The height and width of the frame can also be specified in inches. The default
line style can be over-ridden for sides of the frame by specifying additional
parameters to frame
.
If no plotting commands have been given before the
frame
command is issued, the frame will be
output at that point in the plotting stream relative to embedded
troff or pic
commands. Otherwise the frame is output before the first plotted object (even
invisible ones).
ht
and wid
are in inches by default, but can be any groff
unit. If omitted, the dimensions are 2 inches high by 3 inches wide.coord
[name
]
[x
expr,
expry
expr,
exprlog x
| log y
| log log
The
coord
command
specifies a new coordinate system or sets limits on the default system. It
defines the largest and smallest values that can be plotted, and therefore the
scale of the data in the frame. The limits for the x and y coordinate systems
can be given separately. If a name is given,
that coordinate system is defined, if not the default system is modified.
A coordinate system created by one coord
command may be modified by subsequent coord
commands. A grap
program may declare a
coordinate space using coord
,
copy
a file of data through a macro that
plots the data and finds its maxima and minima, and then define the size of
the coordinate system with a second coord
statement.
This command also determines if a scale is plotted logarithmically.
log log
means the same thing as
log x log y
.draw
[line_name
]
[line_description
]
[plot_string
]
The
draw
command
defines the style with which a given line will be plotted. If
line_name is given, the style is associated
with that name, otherwise the default style is set.
line_description is a
pic line description, and the optional
plot_string is a string to be centered at
each point. The default line description is invis
, and
the default plotting string is a centered bullet, so by default each point is
a filled circle, and they are unconnected. If points are being connected, each
draw
command ends any current line and
begins a new one.
When defining a line style, that is the first
draw
command for a given line name,
specifying no plot string means that there are to be no plot strings. Omitting
the plot string on subsequent draw
commands
addressing the same named line means not to change the plot string. If a line
has been defined with a plot string, and the format is changed by a subsequent
draw
statement, the plot string can be
removed by specifying "" in the
draw
statement.
The plot string can have its format changed through several string_modifiers.
String_modifiers are described in the description of the
plot
command.
The standard defines file includes several macros useful as plot strings,
including bullet
,
square
, and
delta
.
new
is a synonym for
draw
.next
[line_name
]
at
[coordinates_name
]
expr, expr
[line_description
]
The
quoted_string
[next
command
plots the given point using the line style given by
line_name, or the default if none is given.
If line_name is given, it should have been
defined by an earlier draw
command, if not
a new line style with that name is created, initialized the same way as the
default style. The two expressions give the point's x and y values, relative
to the optional coordinate system. That system should have been defined by an
earlier coord
command, if not, grap will
exit. If the optional line_description is
given, it overrides the style's default line description. You cannot over-ride
the plotting string. To use a different plotting string use the
plot
command.
The coordinates may optionally be enclosed in parentheses:
(expr,
expr)string_modifiers
]
[, quoted_string
[
]
... string_modifiers
]at
[coordinates_name
]
expr, expr
plot
expr
[format_string
]
at
[coordinates_name
]
expr, expr
These commands both plot a string at the given point.
In the first case the literal strings are stacked above each other. The
string_modifiers include the pic justification
modifiers (
ljust
,
rjust
,
above
, and
below
), and
absolute and relative size
modifiers. See the
pic documentation for the description of the
justification modifiers. grap
also supports
the aligned
and
unaligned
modifiers which are briefly noted
in the description of the label
command.
The standard defines file includes several macros useful as plot strings,
including bullet
,
square
, and
delta
.
Strings placed by either format of the plot
command are restricted to being within the frame. This can be overridden by
using the unclipped
attribute, which allows
a string to be plotted in or out of the frame. The
-c
and
-C
flags set
unclipped
on all strings, and to prevent a
string from being plotted outside the frame when those flags are active, the
clipped
attribute can be used to retore
clipping behavior. Though clipped
or
unclipped
can be applied to any string, it
only has meaning for plot
statements.
size
expr sets the
string size to expr points. If
expr is preceded by a + or -, the size is
increased or decreased by that many points.
If color
and a color name in double quotes
appears, the string will be rendered in that color under a version of GNU
troff that supports color. Color is not available in compatibility mode.
In the second version, the expr is converted to
a string and placed on the graph.
format_string is a
printf(3) format string. Only formatting escapes
for printing floating point numbers make sense. The format string is only
respected if the sprintf
command is also
active. See the description of sprintf
for
the various ways to disable it. Plot
and
sprintf
respond differently when
grap
is running safely.
Sprintf
ignores any arguments, passing the
format string through without substitution.
plot
ignores the format string completely,
plotting expr using the “%g”
format.
Points are specified the same way as for next
commands, with the same consequences for undefined coordinate systems.
The second form of this command is because the first form can be used with a
grap
sprintf
expression (See
Expressions).ticks
(left
|right
|top
|bottom
)[
(
]
[in
|out
)
[expr
]on|
auto
coord_nameticks
(left
|right
|top
|bottom
)
(in
|out
)
[expr
]
[up
expr |
down
expr
| left
expr |
right
exprat
[coord_name
]
expr
[format_string
]
[[
]
, expr
[
]
...format_string
]ticks
(left
|right
|top
|bottom
)
(in
|out
)
[expr
]
[up
expr |
down
expr
| left
expr |
right
exprfrom
[coord_name
]
start_expr
to
end_expr
[by
[+|-|*|/
]
by_exprformat_string
]
ticks
[left
|right
|top
|bottom
]off
This command controls the placement of ticks on the
frame. By default, ticks are automatically generated on the left and bottom
sides of the frame.
The first version of this command turns on the automatic tick generation for a
given side. The
will put ticks at 2, 4, 8, 16, and 32. If
format_string is specified, all ticks are
formatted using it.
The parameters preceding the
will put ticks on the left side of the frame pointing out at 2, 4, 8, 16, and 32
and in at 3, 5, and 7.
The final form of
in
or
out
parameter controls the direction and
length of the ticks. If a coord_name is
specified, the ticks are automatically generated using that coordinate system.
If no system is specified, the default coordinate system is used. As with
next
and
plot
, the coordinate system must be
declared before the ticks
statement that
references it. This syntax for requesting automatically generated ticks is an
extension, and will not port to older grap
implementations.
The second version of the ticks
command
overrides the automatic placement of the ticks by specifying a list of
coordinates at which to place the ticks. If the ticks are not defined with
respect to the default coordinate system, the
coord_name parameter must be given. For each
tick a printf(3) style format string can be
given. The format_string defaults to
“%g”. The format string can also take string modifiers as
described in the plot
command. To place
ticks with no labels, specify format_string
as “”.
If sprintf
is disabled,
ticks
behaves as
plot
with respect to the format string.
The labels on the ticks may be shifted by specifying a direction and the
distance in inches to offset the label. That is the optional direction and
expression immediately preceding the at
.
The third format of the ticks
command
over-rides the default tick generation with a set of ticks ar regular
intervals. The syntax is reminiscent of programming language for loops. Ticks
are placed starting at start_expr ending at
end_expr one unit apart. If the
by
clause is specified, ticks are
by_expr units apart. If an operator appears
before by_expr each tick is operated on by
that operator instead of +. For example
ticks left out from 2 to 32 by *2
from
act as
described above.
The at
and
for
forms of tick command may both be
issued on the same side of a frame. For example:
ticks left out from 2 to 32 by *2 ticks left in 3, 5, 7
ticks
turns off ticks on a
given side. If no side is given the ticks for all sides are cancelled.
tick
is a synonym for
ticks
.grid
(left
|right
|top
|bottom
)
[ticks off
line_description
]
[up
expr |
down
expr
| left
expr |
right
expron|
auto
[coord_name
]grid
(left
|right
|top
|bottom
)
[ticks off
line_description
]
[up
expr |
down
expr
| left
expr |
right
exprat
[coord_name
]
expr
[format_string
]
[[
]
, expr
[
]
...format_string
]grid
(left
|right
|top
|bottom
)
[ticks off
line_description
]
[up
expr |
down
expr
| left
expr |
right
exprfrom
[coord_name
]
start_expr
to
end_expr
[by
[+|-|*|/
]
by_exprformat_string
]
The
grid
command is
similar to the ticks
command except that
grid
specifies the placement of lines in
the frame. The syntax is similar to ticks
as well.
By specifying ticks off
in the command, no ticks are
drawn on that side of the frame. If ticks appear on a side by default, or have
been declared by an earlier ticks
command,
grid
does not cancel them unless
ticks off
is specified.
Instead of a direction for ticks, grid
allows
the user to pick a line description for the grid lines. The usual
pic line descriptions are allowed.
Grids are labelled by default. To omit labels, specify the format string as
“”.
If sprintf
is disabled,
grid
behaves as
plot
with respect to the format
string.label
(left
|right
|top
|bottom
)
quoted_string
[string_modifiers
]
[, quoted_string
[
]
... [string_modifiers
]up
expr |
down
expr
| left
expr |
right
exprThe
label
command
places a label on the given axis. It is possible to specify several labels,
which will be stacked over each other as in pic.
The final argument, if present, specifies how many inches the label is shifted
from the axis.
By default the labels on the left and right labels run parallel to the frame.
You can cancel this by specifying unaligned
as a
string_modifier.circle
at
[coordinate_name
]
expr, expr
[radius
exprlinedesc
]
This draws an circle at the point indicated. By
default, the circle is small, 0.025 inches. This can be over-ridden by
specifying a radius. The coordinates of the point are relative to the named
coordinate system, or the default system if none is specified.
This command has been extended to take a line description, e.g.,
dotted
. It also accepts the filling extensions
described below in the bar
command. It will
also accept a color
keyword that gives the
color of the outline of the circle in double quotes and a
fillcolor
command that sets the color to
fill the circle with similarly. Colors are only available when compatibility
mode is off, and using a version of GNU pic that supports color.line
[line_description
]
from
[coordinate_name
]
expr, expr
to
[coordinate_name
]
expr, expr
[line_description
]
arrow
[line_description
]
from
[coordinate_name
]
expr, expr
to
[coordinate_name
]
expr, expr
[line_description
]
This draws a line or arrow from the first point to the
second using the given style. The default line style is
solid
. The
line_description can be given either before
the from
or after the
to
clause. If both are given the second is
used. It is possible to specify one point in one coordinate system and one in
another, note that if both points are in a named coordinate system (even if
they are in the same named coordinate system), both points must have
coordinate_name given.copy
[“filename”
]
[until
“string”thru
macroThe
copy
command
imports data from another file into the current graph. The form with only a
filename given is a simple file inclusion; the included file is simply read
into the input stream and can contain arbitrary
grap
commands. The more common case is that
it is a number list; see Number
Lists below.
The second form takes lines from the file, splits them into words delimited by
one or more spaces, and calls the given macro with those words as parameters.
The macro may either be defined here, or be a macro defined earlier. See
Macros for more information on
macros.
The filename may be omitted if the
until
clause is present. If so the current
file is treated as the input file until
string is encountered at the beginning of the
line.
copy
is one of the workhorses of
grap
. Check out the paper and
/usr/share/doc/grap/examples for more
details. Confirm the location of the examples directory using the
-v
flag.print
(expr|string)
Prints its argument to the standard error.
sh
block
This passes block to
sh(1). Unlike K&B
grap
no macro or variable expansion is
done. I believe that this is also true for GNU
pic version 1.10. See the
Macros section for information on
defining blocks.pic
pic_statement
This issues the given pic
statements in the enclosing
.PS
and
.PE
at the point where the command is
issued.
Statements that begin with a period are considered to be
troff(statements) and are output in the enclosing
.PS
and
.PE
at the point where the command appears.
For the purposes of relative placement of pic or
troff commands, the frame is output immediately
before the first plotted object, or the
frame
statement, if any. If the user
specifies pic or
troff commands and neither any plotable object
nor a frame
command, the commands will not
be output.graph
Name
pic_commands
This command is used to position graphs with respect
to each other. The current graph is given the pic
name Name (names used by
pic begin with capital letters). Any
pic commands following the graph are used to
position the next graph. The frame of the graph is available for use with
pic name
name = expr
Frame.
The
following places a second graph below the first:
graph Linear [ graph description ] graph Exponential with .Frame.n at \ Linear.Frame.s - (0, .05) [ graph description ]
This assigns expr to
the variable name.
grap
has only numeric (double) variables.
Assignment creates a variable if it does not exist. Variables persist across
graphs. Assignments can cascade; a = b = 35
assigns 35
to a
and b
.bar
(up
|right
)
[coordinates_name
]
offset ht
height
[wid
widthbase
base_offsetline_description
]
bar
[coordinates_name
]
expr, expr,
[coordinates_name
]
expr, expr,
[line_description
]
The
draws a 2 unit high bar sitting on the x axis, centered on x=3. By default bars
are 1 unit wide, but this can be changed with the
bar
command
facilitates drawing bar graphs. The first form of the command describes the
bar somewhat generally and has grap
place
it. The bar may extend up or to the right, is centered on
offset and extends up or right
height units (in the given coordinate
system). For example
bar up 3 ht 2
wid
keyword. By default bars sit on the
base axis, i.e., bars directed up will extend from y=0. That may be overridden
by the base
keyword. (The bar described
above has corners (2.5, 0) and (3.5, 2).)
The line description has been extended to include a
fill
expr
keyword that specifies the shading inside the bar. Bars may be drawn in any
line style. They support the color
and
fillcolor
keywords described under
circle
.
The second form of the command draws a box with the two points as corners. This
can be used to draw boxes highlighting certain data as well as bar graphs.
Note that filled bars will cover data drawn under them.Control Flow¶
if
expr
then
block
[else
blockThe
behave as expected. A separator is also appended to the end of a
if
statement
provides simple conditional execution. If
expr is non-zero, the
block after the
then
statement is executed. If not the
block after the
else
is executed, if present. See
Macros for the definition of
blocks. Early versions of this implementation of
grap
treated the blocks as macros that were
defined and expanded in place. This led to unnecessary confusion because
explicit separators were sometimes called for. Now,
grap
inserts a separator (;) after the last
character in block, so constructs like
if (x == 3) { y = y + 1 } x = x + 1
for
block.for
name
from
from_expr
to
to_expr
[by
[+|-|*|/
]
by_exprdo
block
This command executes
block iteratively. The variable
name is set to
from_expr and incremented by
by_expr until it exceeds
to_expr. The iteration has the semantics
defined in the
ticks
command. The
definition of block is discussed in
Marcos. See also the note about
implicit separators in the description of the
if
command.
An =
can be used in place of
from
.Expressions¶
grap
supports most standard arithmetic
operators: + - / * ^. The carat (^) is exponentiation. In an
if
statement
grap
also supports the C logical operators
==, !=, &&, || and unary !. Also in an
if
, == and != are overloaded for the
comparison of quoted strings. Parentheses are used for grouping.
Assignment is not allowed in an expression in any context, except for simple
cascading of assignments. a = b = 35
works as
expected; a = 3.5 * (b = 10)
does not execute.
grap
supports the following functions that
take one argument: log
,
exp
,
int
,
sin
,
cos
,
sqrt
,
rand
,
floor
,
ceil
. The logarithms are base 10 and the
trigonometric functions are in radians.
eexp
returns Euler's number to the given
power and ln
returns the natural logarithm.
The natural log, exponentiation functions and floor and ceil are extensions
and are probably not available in other
grap
implementations.
rand
returns a random number uniformly
distributed on [0,1). The following two-argument functions are supported:
atan2
,
min
,
max
.
atan2
works just like
atan2(3). The random number generator can be
seeded by calling srand
with a single
parameter (converted internally to an integer). Because its return value is of
no use, you must use srand
as a separate
statement, it is not part of a valid expression.
srand
is not portable.
The getpid
function takes no arguments and
returns the process id. This may be used to seed the random number generator,
but do not expect cryptographically random values to result.
Other than string comparison, no expressions can use strings. One string valued
function exists: sprintf
(format,
[expr
[
] ). It
operates like sprintf(3), except returning the
value. It can be used anywhere a quoted string is used. If
, expr
]grap
is run with
-S
, the environment variable
GRAP_SAFER
is defined, or
grap
has been compiled for safer operation,
the sprintf
command will return the format
string. This mode of operation is only intended to be used only if
grap
is being used as part of a super-user
enabled print system.
grap
version 1.44 and beyond support two
functions for date and time manipulation,
strptime
and
strptime
.
strptime
parses a time using the
strptime(3) function. It takes two parameters,
both strings, the format and a string to parse using that format and returns a
number that can be sorted directly - the number of seconds since the UNIX
epoch. strftime
does the reverse. It takes
a string and a number and formats the number into a date. In both functions,
the format is the first parameter. The formats are defined in the
documentation for strftime(3).
Macros¶
grap
has a simple but powerful macro
facility. Macros are defined using the
define
command :
define
name
block
undefine
name
Every occurrence of
name in the program text is replaced by the
contents of block.
block is defined by a series of statements in
nested { }'s, or a series of statements surrounded by the same letter. An
example of the latter is
Each time
Macros persist across graphs. The file
/usr/share/grap/grap.defines contains
simple macros for plotting common characters. The
define foo X coord x 1,3 X
foo
appears in the text, it will be replaced
by coord x 1,3
. Macros are literal, and can contain
newlines. If a macro does not span multiple lines, it should end in a
semicolon to avoid parsing errors.
Macros can take parameters, too. If a macro call is followed by a parenthesized,
comma-separated list the values starting with $1 will be replaced in the macro
with the elements of the list. A $ not followed by a digit is left unchanged.
This parsing is very rudimentary; no nesting or parentheses or escaping of
commas is allowed. Also, there is no way to say argument 1 followed by a digit
(${1}0 in sh(1)).
The following will draw a line with slope 1.
define foo { next at $1, $2 } for i from 1 to 5 { foo(i,i) }
undefine
command deletes a macro.
See the directory
/usr/share/doc/grap/examples for more
examples of macros. Confirm the location of the examples directory using the
-v
flag.Number Lists¶
A whitespace-separated list of numbers is treated specially. The list is taken to be points to be plotted using the default line style on the default coordinate system. If more than two numbers are given, the extra numbers are taken to be additional y values to plot at the first x value. Number lists in DWBgrap
can be comma-separated, and this
grap
supports that as well. More precisely,
numbers in number lists can be separated by either whitespace, commas, or
both.
1 2 3 4 5 6
.G1 copy "./data" .G2
Pic Macros¶
grap
defines pic macros that can be used in
embedded pic code to place elements in the graph. The macros are
x_gg
,
y_gg
, and
xy_gg
. These macros define pic distances
that correspond to the given argument. They can be used to size boxes or to
plot pic constructs on the graph. To place a given construct on the graph, you
should add Frame.Origin to it. Other coordinate spaces can be used by
replacing gg
with the name of the
coordinate space. A coordinate space named
gg
cannot be reliably accessed by these
macros.
The macros are emitted immediately before the frame is drawn.
DWB grap
may use these as part of its
implementation. This grap
provides them
only for compatibility. Note that these are very simple macros, and may not do
what you expect under complex conditions.
ENVIRONMENT VARIABLES¶
If the environment variableGRAP_DEFINES
is
defined, grap
will look for its defines
file there. If that value is a relative path name the path specified in the
-M
option will be searched for it.
GRAP_DEFINES
overrides the compiled in
location of the defines file, but may be overridden by the
-d
or -D
flags.
If GRAP_SAFER
is set,
sprintf
is disabled to prevent forcing
grap
to core dump or smash the stack.
FILES¶
/usr/share/grap/grap.definesSEE ALSO¶
atan2(3), groff(1), pic(1), printf(3), sh(1), sprintf(3), troff(1) If documentation and examples have been installed,grap
--version
or
grap
--help
will display the locations.
BUGS¶
There are several small incompatibilities with K&Rgrap
. They include the
sh
command not expanding variables and
macros, and a more strict adherence to parameter order in the internal
commands.
Although much improved, the error reporting code can still be confused. Notably,
an error in a macro is not detected until the macro is used, and it produces
unusual output in the error message.
Iterating many times over a macro with no newlines can run
grap
out of memory.
AUTHOR¶
This implementation was done by Ted Faber ⟨faber@lunabase.org⟩. Bruce Lilly ⟨blilly@erols.com⟩ contributed many bug fixes, including a considerable revamp of the error reporting code. If you can actually find an error in yourgrap
code,
you can probably thank him. grap
was
designed and specified by Brian Kernighan
and Jon Bentley.March 11, 2006 | Debian |