# lib_add_head_tail_html.rb
# add header and tail to body (html)
def add_head_tail_html html_file
sample_md = <<~'EOS'
---
title: 'Gtk4 tutorial for beginners'
---
# sample header
Main contents begin here.
~~~{.C .numberLines}
int main(int argc, char **argv) {
}
~~~
|English|Japanese|
|:-----:|:------:|
|potato|jagaimo|
|carrot|ninjin|
|onion|tamanegi|
EOS
File.write "sample.md", sample_md
stat = system("pandoc", "-s", "-o", "sample.html", "sample.md")
File.delete("sample.md")
raise ("add_head_tail_html: pandoc retuns error status #{$?}.\n") unless stat == true
sample_html = File.read("sample.html")
File.delete("sample.html")
sample_html.gsub!(//,'')
head = sample_html.partition(/<\/head>/)[0]
raise "No