Curl-url-file-3a-2f-2f-2f

To truly understand the keyword, you must experiment (ethically, on your own system).

url="file%3A%2F%2F%2Fhome%2Fuser%2Fdata.txt"
decoded=$(printf '%b' "$url//%/\\x")
curl "$decoded"

If you are a developer or system administrator, the presence of curl-url-file-3A-2F-2F-2F in your environment demands action. curl-url-file-3A-2F-2F-2F

Here are 3 types of content you could create depending on your audience. To truly understand the keyword, you must experiment

When using the curl CLI in scripts, restrict protocols: If you are a developer or system administrator,

curl --proto =http,https --proto-redir =http,https "$url"

This prevents file:// from ever being honored.