see #6: pdf for english version

pdf/zh-cn/aggregator.py

@@ -1,6 +1,8 @@
 # !/usr/bin/env python3
 # author: changkun<hi@changkun.us>
 
+import os
+
 chapters = ['00-preface.md', '01-intro.md',  '02-usability.md', '03-runtime.md', '04-containers.md', '05-pointers.md', '06-regex.md', '07-thread.md', '08-filesystem.md', '09-others.md', '10-cpp20.md', 'appendix.md']
 
 ignores = ['TOC', '返回目录', '许可', 'license']
@@ -13,10 +15,11 @@ copyright: cc-by-nc-nd 4.0
 ---
 """)
     for chapter in chapters:
-        with open(chapter) as ch:
-            outfile.write('\n')
-            for line in ch:
-                if any(keyword in line for keyword in ignores):
-                    continue
-                else:
-                    outfile.write(line)
+        if os.path.isfile(chapter):
+            with open(chapter) as ch:
+                outfile.write('\n')
+                for line in ch:
+                    if any(keyword in line for keyword in ignores):
+                        continue
+                    else:
+                        outfile.write(line)