Info Catalog groff: Escapes groff: Escapes

groff: Comments

 
 5.5.3.1 Comments
 ................
 
 Probably one of the most(1) (⇒Comments-Footnote-1) common forms
 of escapes is the comment.
 
  -- Escape: \"
      Start a comment.  Everything to the end of the input line is
      ignored.
 
      This may sound simple, but it can be tricky to keep the comments
      from interfering with the appearance of the final output.
 
      If the escape is to the right of some text or a request, that
      portion of the line is ignored, but the space leading up to it is
      noticed by 'gtroff'.  This only affects the 'ds' and 'as' request
      and its variants.
 
      One possibly irritating idiosyncracy is that tabs must not be used
      to line up comments.  Tabs are not treated as whitespace between
      the request and macro arguments.
 
      A comment on a line by itself is treated as a blank line, because
      after eliminating the comment, that is all that remains:
 
           Test
           \" comment
           Test
 
      produces
 
           Test
 
           Test
 
      To avoid this, it is common to start the line with '.\"', which
      causes the line to be treated as an undefined request and thus
      ignored completely.
 
      Another commenting scheme seen sometimes is three consecutive
      single quotes (''''') at the beginning of a line.  This works, but
      'gtroff' gives a warning about an undefined macro (namely ''''),
      which is harmless, but irritating.
 
  -- Escape: \#
      To avoid all this, 'gtroff' has a new comment mechanism using the
      '\#' escape.  This escape works the same as '\"' except that the
      newline is also ignored:
 
           Test
           \# comment
           Test
 
      produces
 
           Test Test
 
      as expected.
 
  -- Request: .ig [end]
      Ignore all input until 'gtroff' encounters the macro named '.'END
      on a line by itself (or '..' if END is not specified).  This is
      useful for commenting out large blocks of text:
 
           text text text...
           .ig
           This is part of a large block
           of text that has been
           temporarily(?) commented out.
 
           We can restore it simply by removing
           the .ig request and the ".." at the
           end of the block.
           ..
           More text text text...
 
      produces
 
           text text text...  More text text text...
 
      Note that the commented-out block of text does not cause a break.
 
      The input is read in copy-mode; auto-incremented registers _are_
      affected (⇒Auto-increment).
 

Info Catalog groff: Escapes groff: Escapes