Convert from old categories to tags

import sys
import yaml

with open(sys.argv[1]) as fp:
    data = fp.read()

if not data.find("---") == 0:
    # no head
    print("NO YAML HEAD FOUND")
    sys.exit(-1)

data = data[3:]
head_end = data.find("---")

head = data[0:head_end]
data = data[head_end+3:]

metadata = yaml.safe_load(head)

cats = metadata.pop('categories', None)
if cats != None:
    if type(cats) == list:
        tags = cats
    elif type(cats) == str:
        tags = cats.split()

    tags = list(map(lambda t: t.lower(), tags))

    metadata["tags"] = ", ".join(tags)
    new_data = f"---\n{yaml.dump(metadata, default_flow_style=False)}---{data}"
    # write it
    print(f"coverted: categories to tags: {tags} - {sys.argv[1]}")
    with open(sys.argv[1], "w") as fp:
        fp.write(new_data)
    sys.exit(0)

if not metadata.get("tags", None):
    metadata["tags"] = "untagged"
    new_data = f"---\n{yaml.dump(metadata, default_flow_style=False)}---{data}"
    print(f"untagged: {sys.argv[1]}")
    # write it
    with open(sys.argv[1], "w") as fp:
        fp.write(new_data)
    sys.exit(0)

print("No changes needed")

blog/2017-08-02-linux-4.12.markdown

@@ -1,13 +1,9 @@
 ---
-layout: post
-title: "Linux-4.12 "
-date: 2017-08-02
 comments: true
-categories:
-  - linux
-  - kernel
-  - systems
-  - code
+date: 2017-08-02
+layout: post
+tags: linux, kernel, systems, code
+title: 'Linux-4.12 '
 ---
 
 Linux 4.12 was released few weeks ago. Its always nice to get a new version of kernel, but this time it was extra sweet, I managed to get some tiny commits merged to the release.