pic - compile pictures for troff or TeX


   pic [ -nvCSU ] [ filename ... ]
   pic -t [ -cvzCSU ] [ filename ... ]


   This manual page describes the GNU version of pic, which is part of the
   groff  document  formatting  system.   pic  compiles  descriptions   of
   pictures  embedded  within  troff or TeX input files into commands that
   are understood by TeX or  troff.   Each  picture  starts  with  a  line
   beginning  with  .PS and ends with a line beginning with .PE.  Anything
   outside of .PS and .PE is passed through without change.

   It is the user's responsibility to provide appropriate  definitions  of
   the  PS  and  PE  macros.   When  the macro package being used does not
   supply such definitions (for example, old versions of -ms), appropriate
   definitions can be obtained with -mpic: These will center each picture.


   Options  that  do  not take arguments may be grouped behind a single -.
   The special option -- can be used to mark the end of  the  options.   A
   filename of - refers to the standard input.

   -C     Recognize  .PS  and  .PE even when followed by a character other
          than space or newline.

   -S     Safer mode; do not execute sh commands.  This can be useful when
          operating on untrustworthy input (enabled by default).

   -U     Unsafe mode; revert the default option -S.

   -n     Don't  use  the  groff extensions to the troff drawing commands.
          You should use this  if  you  are  using  a  postprocessor  that
          doesn't  support these extensions.  The extensions are described
          in groff_out(5).  The -n option also causes pic not to use zero-
          length lines to draw dots in troff mode.

   -t     TeX mode.

   -c     Be more compatible with tpic.  Implies -t.  Lines beginning with
          \ are not passed through transparently.  Lines beginning with  .
          are  passed  through  with  the initial .  changed to \.  A line
          beginning with .ps is  given  special  treatment:  it  takes  an
          optional  integer  argument  specifying  the line thickness (pen
          size) in milliinches; a missing argument restores  the  previous
          line  thickness;  the  default  line thickness is 8 milliinches.
          The line thickness thus specified takes effect only when a  non-
          negative  line  thickness  has  not been specified by use of the
          thickness attribute or by setting the linethick variable.

   -v     Print the version number.

   -z     In TeX mode draw dots using zero-length lines.

   The following options supported by other versions of pic are ignored:

   -D     Draw all lines using the \D escape sequence.   pic  always  does

   -T dev Generate  output  for the troff device dev.  This is unnecessary
          because the troff output generated by pic is device-independent.


   This section describes only the differences between  GNU  pic  and  the
   original version of pic.  Many of these differences also apply to newer
   versions of Unix pic.  A complete documentation  is  available  in  the


   TeX mode
   TeX  mode  is enabled by the -t option.  In TeX mode, pic will define a
   vbox called \graph for each picture.  Use the figname command to change
   the  name  of  the  vbox.  You must yourself print that vbox using, for
   example, the command

          \centerline{	ox\graph}

   Actually, since the vbox has a height  of  zero  (it  is  defined  with
   \vtop) this will produce slightly more vertical space above the picture
   than below it;

          \centerline{\raise 1em	ox\graph}

   would avoid this.

   To make the vbox having a positive height and a depth of zero (as  used
   e.g.  by  LaTeX's  graphics.sty),  define  the  following macro in your

             \vbox{\unvbox\csname #1\endcsname\kern 0pt}}

   Now you can simply say \gpicbox{graph} instead of 	ox\graph.

   You must use a TeX driver that supports the tpic specials, version 2.

   Lines beginning with \ are passed through transparently; a %  is  added
   to  the  end  of the line to avoid unwanted spaces.  You can safely use
   this feature to change fonts or to change the value  of  	aselineskip.
   Anything  else  may  well  produce undesirable results; use at your own
   risk.  Lines  beginning  with  a  period  are  not  given  any  special

   for variable = expr1 to expr2 [by [*]expr3] do X body X
          Set variable to expr1.  While the value of variable is less than
          or equal to expr2, do body and increment variable by  expr3;  if
          by  is not given, increment variable by 1.  If expr3 is prefixed
          by * then variable will instead be  multiplied  by  expr3.   The
          value  of  expr3 can be negative for the additive case; variable
          is then tested whether it is greater than  or  equal  to  expr2.
          For  the  multiplicative  case, expr3 must be greater than zero.
          If the constraints aren't met, the loop isn't executed.   X  can
          be any character not occurring in body.

   if expr then X if-true X [else Y if-false Y]
          Evaluate  expr;  if it is non-zero then do if-true, otherwise do
          if-false.  X can be any character not occurring in  if-true.   Y
          can be any character not occurring in if-false.

   print arg...
          Concatenate  the  arguments and print as a line on stderr.  Each
          arg must be an expression, a position, or text.  This is  useful
          for debugging.

   command arg...
          Concatenate  the  arguments  and  pass them through as a line to
          troff or TeX.  Each arg must be an expression,  a  position,  or
          text.   This  has a similar effect to a line beginning with . or
          \, but allows the values of variables to be passed through.  For

                 x = 14
                 command ".ds string x is " x "."


                 x is 14.

   sh X command X
          Pass  command  to a shell.  X can be any character not occurring
          in command.

   copy "filename"
          Include filename at this point in the file.

   copy ["filename"] thru X body X [until "word"]
   copy ["filename"] thru macro [until "word"]
          This construct does body once for each  line  of  filename;  the
          line  is split into blank-delimited words, and occurrences of $i
          in body, for i between 1 and 9, are replaced by the i-th word of
          the  line.   If  filename is not given, lines are taken from the
          current input up to .PE.  If an until clause is specified, lines
          will  be read only until a line the first word of which is word;
          that line will then be discarded.  X can be  any  character  not
          occurring in body.  For example,

                 copy thru % circle at ($1,$2) % until "END"
                 1 2
                 3 4
                 5 6

          is equivalent to

                 circle at (1,2)
                 circle at (3,4)
                 circle at (5,6)

          The  commands  to  be  performed for each line can also be taken
          from a macro defined earlier by giving the name of the macro  as
          the argument to thru.

   reset variable1[,] variable2 ...
          Reset  pre-defined  variables  variable1, variable2 ... to their
          default values.  If no  arguments  are  given,  reset  all  pre-
          defined  variables to their default values.  Note that assigning
          a value to scale also  causes  all  pre-defined  variables  that
          control dimensions to be reset to their default values times the
          new value of scale.

   plot expr ["text"]
          This is a text object which is constructed by using  text  as  a
          format  string for sprintf with an argument of expr.  If text is
          omitted a format string of "%g"  is  used.   Attributes  can  be
          specified  in the same way as for a normal text object.  Be very
          careful that you specify an appropriate format string; pic  does
          only very limited checking of the string.  This is deprecated in
          favour of sprintf.

   variable := expr
          This is similar to = except variable must  already  be  defined,
          and  expr  will  be  assigned  to  variable  without  creating a
          variable local to the current block.  (By  contrast,  =  defines
          the  variable  in the current block if it is not already defined
          there, and then changes the value in the  current  block  only.)
          For example, the following:

                 x = 3
                 y = 3
                   x := 5
                   y = 5
                 print x " " y


                 5 3

   Arguments of the form

          X anything X

   are also allowed to be of the form

          { anything }

   In  this  case  anything  can  contain balanced occurrences of { and }.
   Strings may contain X or imbalanced occurrences of { and }.

   The syntax for expressions has been significantly extended:

   x ^ y (exponentiation)
   atan2(y, x)
   log(x) (base 10)
   exp(x) (base 10, i.e. 10^x)
   rand() (return a random number between 0 and 1)
   rand(x) (return a random number between 1 and x; deprecated)
   srand(x) (set the random number seed)
   max(e1, e2)
   min(e1, e2)
   e1 && e2
   e1 || e2
   e1 == e2
   e1 != e2
   e1 >= e2
   e1 > e2
   e1 <= e2
   e1 < e2
   "str1" == "str2"
   "str1" != "str2"

   String comparison expressions must be parenthesised in some contexts to
   avoid ambiguity.

   Other Changes
   A  bare  expression,  expr,  is  acceptable  as  an  attribute;  it  is
   equivalent to dir expr,  where  dir  is  the  current  direction.   For

          line 2i

   means  draw a line 2 inches long in the current direction.  The ‘i’ (or
   ‘I’) character is ignored; to use another  measurement  unit,  set  the
   scale variable to an appropriate value.

   The  maximum  width  and  height  of  the  picture  are  taken from the
   variables maxpswid and maxpsht.  Initially these have  values  8.5  and

   Scientific notation is allowed for numbers.  For example

          x = 5e-2

   Text attributes can be compounded.  For example,

          "foo" above ljust

   is valid.

   There  is  no  limit to the depth to which blocks can be examined.  For

          [A: [B: [C: box ]]] with .A.B.C.sw at 1,2
          circle at last [].A.B.C

   is acceptable.

   Arcs now have compass points determined by the circle of which the  arc
   is a part.

   Circles,  ellipses,  and  arcs  can  be  dotted or dashed.  In TeX mode
   splines can be dotted or dashed also.

   Boxes can have rounded corners.  The rad attribute specifies the radius
   of  the quarter-circles at each corner.  If no rad or diam attribute is
   given, a radius of boxrad is used.  Initially, boxrad has a value of 0.
   A box with rounded corners can be dotted or dashed.

   Boxes  can have slanted sides.  This effectively changes the shape of a
   box from a rectangle to an arbitrary parallelogram.  The  xslanted  and
   yslanted attributes specify the x and y offset of the box's upper right
   corner from its default position.

   The .PS line can have a second argument specifying a maximum height for
   the  picture.   If  the  width  of  zero is specified the width will be
   ignored in computing the scaling factor for the picture.  Note that GNU
   pic  will  always scale a picture by the same amount vertically as well
   as horizontally.  This is different from the  DWB  2.0  pic  which  may
   scale a picture by a different amount vertically than horizontally if a
   height is specified.

   Each text object has an invisible box associated with it.  The  compass
   points  of  a  text  object  are  determined by this box.  The implicit
   motion associated with the object is also determined by this box.   The
   dimensions  of this box are taken from the width and height attributes;
   if the width attribute is not supplied then the width will be taken  to
   be  textwid;  if  the  height attribute is not supplied then the height
   will be taken to be the number of  text  strings  associated  with  the
   object times textht.  Initially textwid and textht have a value of 0.

   In  (almost  all)  places  where  a  quoted text string can be used, an
   expression of the form

          sprintf("format", arg,...)

   can also be used; this will produce the arguments  formatted  according
   to  format,  which  should  be  a  string  as  described  in  printf(3)
   appropriate for the number of arguments supplied.

   The thickness of the lines used to draw objects is  controlled  by  the
   linethick  variable.   This  gives the thickness of lines in points.  A
   negative value means use the default thickness:  in  TeX  output  mode,
   this  means  use  a thickness of 8 milliinches; in TeX output mode with
   the -c option, this means use  the  line  thickness  specified  by  .ps
   lines; in troff output mode, this means use a thickness proportional to
   the pointsize.  A zero value means  draw  the  thinnest  possible  line
   supported by the output device.  Initially it has a value of -1.  There
   is also a thick[ness] attribute.  For example,

          circle thickness 1.5

   would draw a circle using a line with a thickness of 1.5  points.   The
   thickness  of lines is not affected by the value of the scale variable,
   nor by the width or height given in the .PS line.

   Boxes (including boxes with rounded corners or slanted sides),  circles
   and  ellipses  can  be  filled by giving them an attribute of fill[ed].
   This takes an optional argument of an expression with a value between 0
   and  1; 0 will fill it with white, 1 with black, values in between with
   a proportionally gray shade.  A value greater than 1 can also be  used:
   this means fill with the shade of gray that is currently being used for
   text and lines.  Normally this will be black, but  output  devices  may
   provide  a  mechanism for changing this.  Without an argument, then the
   value of the variable fillval will be used.  Initially this has a value
   of  0.5.   The  invisible  attribute  does  not  affect  the filling of
   objects.  Any text associated with a filled object will be added  after
   the  object  has  been filled, so that the text will not be obscured by
   the filling.

   Three additional modifiers are available to  specify  colored  objects:
   outline[d]  sets  the  color of the outline, shaded the fill color, and
   colo[u]r[ed] sets both.  All three keywords expect a suffix  specifying
   the color, for example

          circle shaded "green" outline "black"

   Currently, color support isn't available in TeX mode.  Predefined color
   names for groff are in the device macro  files,  for  example  ps.tmac;
   additional  colors  can  be defined with the .defcolor request (see the
   manual page of troff(1) for more details).

   To change the name of the vbox in TeX  mode,  set  the  pseudo-variable
   figname  (which  is  actually  a  specially  parsed  command)  within a
   picture.  Example:

          figname = foobar;

   The picture is then available in the box \foobar.

   pic assumes that at the beginning of a  picture  both  glyph  and  fill
   color are set to the default value.

   Arrow  heads will be drawn as solid triangles if the variable arrowhead
   is non-zero and either TeX mode is enabled or the  -n  option  has  not
   been  given.   Initially  arrowhead  has a value of 1.  Note that solid
   arrow heads are always filled with the current outline color.

   The troff output of  pic  is  device-independent.   The  -T  option  is
   therefore  redundant.   All  numbers are taken to be in inches; numbers
   are never interpreted to be in troff machine units.

   Objects can have an aligned attribute.  This  will  only  work  if  the
   postprocessor  is grops, or gropdf.  Any text associated with an object
   having the aligned attribute will be rotated about the  center  of  the
   object  so  that it is aligned in the direction from the start point to
   the end point of the object.  Note that this  attribute  will  have  no
   effect for objects whose start and end points are coincident.

   In places where nth is allowed ‘exprth is also allowed.  Note that ’th
   is a single token: no space is allowed between the ’ and the  th.   For

          for i = 1 to 4 do {
             line fromith box.nw toi+1th box.se


   To  obtain a stand-alone picture from a pic file, enclose your pic code
   with .PS and .PE requests; roff configuration commands may be added  at
   the beginning of the file, but no roff text.

   It  is  necessary  to feed this file into groff without adding any page
   information, so you must check which .PS and .PE requests are  actually
   called.  For example, the mm macro package adds a page number, which is
   very annoying.  At the moment, calling standard groff without any macro
   package  works.   Alternatively, you can define your own requests, e.g.
   to do nothing:

          .de PS
          .de PE

   groff itself does not provide direct  conversion  into  other  graphics
   file  formats.   But  there  are  lots  of  possibilities  if you first
   transform your picture into PostScript® format using the  groff  option
   -Tps.   Since this ps-file lacks BoundingBox information it is not very
   useful by itself, but it may be fed  into  other  conversion  programs,
   usually  named  ps2other  or  pstoother  or  the  like.   Moreover, the
   PostScript  interpreter  ghostscript   (gs)   has   built-in   graphics
   conversion devices that are called with the option

          gs -sDEVICE=<devname>


          gs --help

   for a list of the available devices.

   An  alternative  may be to use the -Tpdf option to convert your picture
   directly into PDF format.  The MediaBox of the  file  produced  can  be
   controlled by passing a -P-p papersize to groff.

   As the Encapsulated PostScript File Format EPS is getting more and more
   important, and the conversion wasn't regarded trivial in the  past  you
   might  be  interested  to  know  that  there is a conversion tool named
   ps2eps which does the right job.  It  is  much  better  than  the  tool
   ps2epsi packaged with gs.

   For  bitmapped  graphic  formats, you should use pstopnm; the resulting
   (intermediate) PNM file can be then converted to virtually any graphics
   format using the tools of the netpbm package .


          Example definitions of the PS and PE macros.


   troff(1),   groff_out(5),   tex(1),   gs(1),   ps2eps(1),   pstopnm(1),
   ps2epsi(1), pnm(5)

   Eric S. Raymond, Making Pictures With GNU PIC.
   /usr/share/doc/groff-base/pic.ps (this file, together with  its  source
   file, pic.ms, is part of the groff documentation)

   Tpic: Pic for TeX

   Brian  W.  Kernighan,  PIC   A Graphics Language for Typesetting (User
   Manual).  AT&T Bell Laboratories, Computing  Science  Technical  Report
   No. 116
   <http://cm.bell-labs.com/cm/cs/cstr/116.ps.gz> (revised May, 1991).

   ps2eps is available from CTAN mirrors, e.g.

   W. Richard Stevens, Turning PIC Into HTML

   W. Richard Stevens, Examples of picMacros


   Input  characters  that  are  invalid for groff (i.e., those with ASCII
   code 0, or 013 octal, or between 015 and 037 octal, or between 0200 and
   0237 octal) are rejected even in TeX mode.

   The  interpretation  of  fillval  is  incompatible with the pic in 10th
   edition Unix, which interprets 0 as black and 1 as white.

   PostScript® is a registered trademark of Adobe Systems Incorporation.


   Copyright © 1989-2014 Free Software Foundation, Inc.

   Permission is granted to make and distribute verbatim  copies  of  this
   manual  provided  the  copyright  notice and this permission notice are
   preserved on all copies.

   Permission is granted to copy and distribute modified versions of  this
   manual  under  the  conditions  for verbatim copying, provided that the
   entire resulting derived work is  distributed  under  the  terms  of  a
   permission notice identical to this one.

   Permission  is  granted  to  copy  and  distribute translations of this
   manual into another language, under the above conditions  for  modified
   versions,  except  that  this  permission  notice  may  be  included in
   translations approved by the Free Software Foundation instead of in the
   original English.


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