What is undefined.md

You often need to create markdown files, so you can run touch filename.md to create them, but the one problem is you need to type the tedious suffix .md.
So you wrote a Node.js script named touchmd to improve the situation:

1
2
3

cat /usr/local/bin/touchmd
#!/usr/bin/env node
require('fs').writeFileSync(process.argv[2] + '.md', '');

Then you ran touchmd README to create README.md, ran touchmd CHANGELOG to get CHANGELOG.md and so on.

1
2
3
4

mkdir the-greatest-project && cd "$_" && touchmd README && ls
README.md
touchmd CHANGELOG && ls
CHANGELOG.md  README.md

The script worked perfect and you got happy.

One day, you accidentally ran touchmd without any parameters.

1

mkdir yet-another-the-greatest-project && cd "$_" && touchmd

Guess what did you get?

1
2

ls
undefined.md

Congratulations! You got the undefined.md.