1 #! /usr/bin/perl -w

     2 

     3 # Script to take the output of nroff -man and remove all the backspacing and

     4 # the page footers and the screen commands etc so that it is more usefully

     5 # readable online. In fact, in the latest nroff, intermediate footers don't

     6 # seem to be generated any more.

     7 

     8 $blankcount = 0;

     9 $lastwascut = 0;

    10 $firstheader = 1;

    11 

    12 # Input on STDIN; output to STDOUT.

    13 

    14 while (<STDIN>)

    15   {

    16   s/\x1b\[\d+m//g;   # Remove screen controls "ESC [ number m"

    17   s/.\x8//g;         # Remove "char, backspace"

    18 

    19   # Handle header lines. Retain only the first one we encounter, but remove

    20   # the blank line that follows. Any others (e.g. at end of document) and the

    21   # following blank line are dropped.

    22 

    23   if (/^PCRE(\w*)\(([13])\)\s+PCRE\1\(\2\)$/)

    24     {

    25     if ($firstheader)

    26       {

    27       $firstheader = 0;

    28       print;

    29       $lastprinted = $_;

    30       $lastwascut = 0;

    31       }

    32     $_=<STDIN>;       # Remove a blank that follows

    33     next;

    34     }

    35 

    36   # Count runs of empty lines

    37 

    38   if (/^\s*$/)

    39     {

    40     $blankcount++;

    41     $lastwascut = 0;

    42     next;

    43     }

    44 

    45   # If a chunk of lines has been cut out (page footer) and the next line

    46   # has a different indentation, put back one blank line.

    47 

    48   if ($lastwascut && $blankcount < 1 && defined($lastprinted))

    49     {

    50     ($a) = $lastprinted =~ /^(\s*)/;

    51     ($b) = $_ =~ /^(\s*)/;

    52     $blankcount++ if ($a ne $b);

    53     }

    54 

    55   # We get here only when we have a non-blank line in hand. If it was preceded

    56   # by 3 or more blank lines, read the next 3 lines and see if they are blank.

    57   # If so, remove all 7 lines, and remember that we have just done a cut.

    58 

    59   if ($blankcount >= 3)

    60     {

    61     for ($i = 0; $i < 3; $i++)

    62       {

    63       $next[$i] = <STDIN>;

    64       $next[$i] = "" if !defined $next[$i];

    65       $next[$i] =~ s/\x1b\[\d+m//g;   # Remove screen controls "ESC [ number m"

    66       $next[$i] =~ s/.\x8//g;         # Remove "char, backspace"

    67       }

    68 

    69     # Cut out chunks of the form <3 blanks><non-blank><3 blanks>

    70 

    71     if ($next[0] =~ /^\s*$/ &&

    72         $next[1] =~ /^\s*$/ &&

    73         $next[2] =~ /^\s*$/)

    74       {

    75       $blankcount -= 3;

    76       $lastwascut = 1;

    77       }

    78 

    79     # Otherwise output the saved blanks, the current, and the next three

    80     # lines. Remember the last printed line.

    81 

    82     else

    83       {

    84       for ($i = 0; $i < $blankcount; $i++) { print "\n"; }

    85       print;

    86       for ($i = 0; $i < 3; $i++)

    87         {

    88         $next[$i] =~ s/.\x8//g;

    89         print $next[$i];

    90         $lastprinted = $_;

    91         }

    92       $lastwascut = 0;

    93       $blankcount = 0;

    94       }

    95     }

    96 

    97   # This non-blank line is not preceded by 3 or more blank lines. Output

    98   # any blanks there are, and the line. Remember it. Force two blank lines

    99   # before headings.

   100 

   101   else

   102     {

   103     $blankcount = 2 if /^\S/ && !/^Last updated/ && !/^Copyright/ &&

   104       defined($lastprinted);

   105     for ($i = 0; $i < $blankcount; $i++) { print "\n"; }

   106     print;

   107     $lastprinted = $_;

   108     $lastwascut = 0;

   109     $blankcount = 0;

   110     }

   111   }

   112 

   113 # End