# Converting troff to HTML

in
Ok, more specifically, troff using the mm macros to HTML. This is another from my "rusty scripts" collection which was written for a specific task long ago. In this case, we were converting some internal documentation from troff using the mm macros into HTML.

troff is a very sophisticated system so doing this right would be a lot of work. But, writing something to get rid of 90% of the grunt work of conversion is pretty easy. Paul Dunne did one for the ms macro set which you can find here but mm is different.

As awk was (and maybe still is) my favorite choice for one-shot "fix the data" programs, it got called to duty to do the task. Here is what I decided was worth it.

#!/usr/bin/awk -f
# troff -mm to HTML converter
# Phil Hughes--April 21, 1997
#
#
# This doesn't do everything and it is not intended to do everyting.
# It does what is easy.  In particular, headers and the title is
# not mucked with.  Also, center requests only center one line (I think).
#
# The goal here was to do the stuff that is a total pain to do by hand.
# This includes section numbering, font changes (which is still rather
# dumb) and lists.  The output of this program should be considered
# a good starting point for making good HTML.
#
# Here is what is currently recognized:
#   .H - deals with heading levels
#   .P - maps to <p> (as does a blank line)
#   .BL - maps to <ul>
#   .AL - maps to <ol>
#   .LE - maps to the end of the list of the type most recently started
#   .LI - <li>
#   .ds - tossed
#   .ce - centers next line
#   \fB, \f(HB, \fI, - changes to bold, bold or italic
#   \fP - goes back to previous font
#   \(em - --
#   .PF, .PH - tossed
#   \s - tossed
# That's all folks.
#

BEGIN   {
BLANKS = "                                                "
# beginning HTML crap
print "<html>"
print "<title> ============</title>"
print "<body>"
}

{       # always convert these things
# yes, there is a lot to add here
gsub(/\\\(em/, "--")    # \em to --
gsub(/.\\".*$/, "") # trash comments gsub(/.PF.*$/, "")      # trash all sorts of headers & footers
gsub(/.PH.*$/, "") # trash all sorts of headers & footers gsub(/\\s[0-9+-][1-9]?/, "") # trash point size changes } /^\.H / { # heading head_level =$2

$1 = ""$2 = ""
gsub(/"/,"")

for (x=1; x <= head_level; x++) {
}
printf " "
print $0 "</h" head_level ">" next } /^ *$/  {       # paragraph
"<p>"
next
}

/^\.P */ { # paragraph print "<p>" next } /^\.BL/ { # bulleted list print "<ul>" list[++ll] = "</ul>" indent += 2 next } /^\.AL/ { # alpha list print "<ol>" list[++ll] = "</ol>" indent += 2 next } /^\.LI/ { # list item print substr(BLANKS, 1, indent) "<li>" next } /^\.LE/ { # list end print list[ll--] indent -= 2 next } /\.ds/ { # trash them next } /^\.ce/ { # center next line(s)--only does one line for now print "<p align=\"center\">" next } { # print whatever we have left # hard stuff like font changes where we need to remember split(0,tmp,"\\")
for (x in tmp) {
if (sub(/^fB/, "<b>", tmp[x]) == 1) {
new_sub = "</b>"
}
if (sub(/^f\(HB/, "<b>", tmp[x]) == 1) {
new_sub = "</b>"
}
if (sub(/^fI/, "<i>", tmp[x]) == 1) {
new_sub = "</i>"
}
if (sub(/^fP/, new_sub, tmp[x]) == 1) {
new_sub = "#####"
}
}

for (x in tmp) {
printf "%s", substr(BLANKS, 1, indent)
printf "%s", tmp[x]
}
print ""
}

END     {
# ending HTML crap
print "</body>"
print "</html>"
}



Most of this is pretty ordinary and brute force. Note that the indenting I add in the output is cosmetic to make it easier to see what is going on. The only "hard part" was dealing with the headings.

In troff with mm, headings are of the form section.subsection.subsubsection ... followed by text. For example, 3.5.1 This is a test would be a standard looking heading. I put this together by using an HTML heading tag of a corresponding level manually counting the number of sections at the current level. For those unfamiliar with awk, let's look at this piece of the code:

        head[head_level]++
$1 = ""$2 = ""
gsub(/"/,"")

printf ""
for (x=1; x <= head_level; x++) {