Provided by: groff-base_1.23.0-2_amd64 bug


       pic - compile pictures for troff or TeX


       pic [-CnSU] [file ...]

       pic -t [-cCSUz] [file ...]

       pic --help

       pic -v
       pic --version


       The  GNU implementation of pic is part of the groff(1) document formatting system.  pic is
       a troff(1) preprocessor that translates descriptions of diagrammatic pictures embedded  in
       roff(7)  or  TeX  input files into the language understood by TeX or troff.  It copies the
       contents of each file to the standard output stream, except that lines between .PS and any
       of  .PE,  .PF,  or .PY are interpreted as picture descriptions in the pic language.  End a
       pic picture with .PE to leave the drawing position at the bottom of the picture, and  with
       .PF  or  .PY  to leave it at the top.  Normally, pic is not executed directly by the user,
       but invoked by specifying the -p option to groff(1).  If no file operands are given on the
       command line, or if file is “-”, the standard input stream is read.

       It  is the user's responsibility to provide appropriate definitions of the PS, PE, and one
       or both of the PF and PY macros.  When a macro  package  does  not  supply  these,  obtain
       simple definitions with the groff option -mpic; these will center each picture.

       GNU  pic  supports PY as a synonym of PF to work around a name space collision with the mm
       macro package, which defines PF as a page footer management macro.  Use PF  preferentially
       unless a similar problem faces your document.


       --help displays a usage message, while -v and --version show version information; all exit

       -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.

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

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

       -S     Operate in safer mode; sh commands are ignored.  This mode, enabled by default, can
              be useful when operating on untrustworthy input.

       -t     Produce TeX output.

       -U     Operate in unsafe mode; sh commands are interpreted.

       -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.  GNU pic always does this.

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


       This  section  primarily  discusses the differences between GNU pic and the Eighth Edition
       Research Unix version of AT&T pic (1985).  Many of these differences also apply  to  later
       versions of AT&T pic.

   TeX mode
       TeX-compatible  output  is  produced  when the -t option is specified.  You must use a TeX
       driver that supports tpic version 2 specials.  (tpic was a fork of AT&T pic by Tim  Morgan
       of  the  University of California at Irvine that diverged from its source around 1984.  It
       is best known today for lending its name to a group of \special commands it  produced  for

       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  the
       value  of  \baselineskip.  Anything else may well produce undesirable results; use at your
       own risk.  By default, lines beginning with a dot are not treated specially—but see the -c

       In TeX mode, pic will define a vbox called \graph for each picture.  Use GNU pic's figname
       command to change the name of the vbox.  You must  print  that  vbox  yourself  using  the
       for  instance.   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\box\graph}
       would avoid this.  To give the vbox a positive height and a depth  of  zero  (as  used  by
       LaTeX's graphics.sty, for example) define the following macro in your document.
                \vbox{\unvbox\csname #1\endcsname\kern 0pt}}
       You can then simply say \gpicbox{graph} instead of \box\graph.

       Several  commands new to GNU pic accept delimiters, shown in their synopses as braces { }.
       Nesting of braces is supported.  Any other characters (except a space,  tab,  or  newline)
       may  be  used as alternative delimiters, in which case the members of a given pair must be
       identical.  Strings are recognized within delimiters of either kind; they may contain  the
       delimiter character or unbalanced braces.

       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

       print arg ...
              Concatenate and write arguments to the standard error stream followed by a newline.
              Each arg must be an expression, a position, or text.  This is useful for debugging.

       command arg ...
              Concatenate arguments and pass them as a line to troff or TeX.  Each arg must be an
              expression,  a position, or text.  command allows the values of pic variables to be
              passed to the formatter.  For example,
                     x = 14
                     command ".ds string x is " x "."
                     x is 14.
              when formatted with troff.

       sh X command X
              Pass command to a shell.

       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
                     circle at (1,2)
                     circle at (3,4)
                     circle at (5,6)
              are  equivalent.  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.
              The  argument  after  thru  is looked up as a macro name first; if not defined, its
              first character is interpreted as a delimiter.

       reset pvar1[,] pvar2 ...
              Reset predefined variables  pvar1,  pvar2  ...  to  their  default  values;  if  no
              arguments  are  given,  reset  all  predefined  variables  to their default values.
              Variable names may be separated by commas, spaces, or both.  Assigning a  value  to
              scale  also  causes all predefined 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.

       var := expr
              This syntax resembles variable assignment with = except that var  must  already  be
              defined,  and expr will be assigned to var without creating a variable local to the
              current block.  (By contrast, = defines var in the  current  block  if  it  is  not
              already  defined there, and then changes the value in the current block only.)  For
                     x = 3
                     y = 3
                     x := 5
                     y = 5
                     print x   y
                     5 3
              to the standard error stream.

       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 example

              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 11.

       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 example,

              [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.  GNU pic will always scale a picture by the  same  amount  vertically  as
       well  as  horizontally.  This is different from 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.  Only the modifiers “#”, “-”, “+”, and “ ” [space]), a minimum field  width,  an
       optional  precision,  and  the  conversion  specifiers  %e,  %E,  %f,  %g,  %G, and %% are

       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.

       Additional  modifiers  are available to draw colored objects: outline[d] sets the color of
       the outline, shaded the fill color, and colo[u]r[ed] sets both.  All expect  a  subsequent
       string argument specifying the color.
              circle shaded "green" outline "black"
       Color  is  not  yet  supported in TeX mode.  Device macro files like ps.tmac declare color
       names; you can define additional ones with the defcolor request (see groff(7)).

       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.  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

       Objects can have an aligned attribute.  This  will  only  work  if  the  postprocessor  is
       grops(1)  or  gropdf(1).   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.  This attribute will have no effect on
       objects whose start and end points are coincident.

       In places where nth is allowed, 'expr'th is also allowed.  “'th“ is  a  single  token:  no
       space is allowed between the apostrophe and the “th”.  For example,

              for i = 1 to 4 do {
                 line from 'i'th box.nw to 'i+1'th


       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(1)) 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(5)
       file can be then converted to virtually any graphics format using the tools of the  netpbm


              offers simple definitions of the PS, PE, PF, and PY macros.


       Characters  that  are  invalid  as  input  to  GNU  troff (see the groff Texinfo manual or
       groff_char(7) for a list) are rejected even in TeX mode.

       The interpretation of fillval is incompatible with the pic in Tenth Edition Research Unix,
       which interprets 0 as black and 1 as white.

See also

              “Making  Pictures  with GNU pic”, by Eric S. Raymond.  This file, together with its
              source,, is part of the groff distribution.

       “PIC—A Graphics Language for Typesetting:  User  Manual”,  by  Brian  W.  Kernighan,  1984
       (revised 1991), AT&T Bell Laboratories Computing Science Technical Report No. 116

       ps2eps  is  available  from  CTAN  mirrors, e.g., ⟨

       W. Richard Stevens,  Turning  PIC  into  HTML

       W. Richard Stevens, Examples of pic Macros

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