If PHP does cache a permanent redirect:
- For how long?
- Can this period be changed?
I would also be interested in the default behaviour on this matter of Perl, Python, and any other languages used primarily for web development
The http_fopen_wrapper.c which is used by file_get_contents() contains no caching logic whatsoever. In particular it responds to the Location: header only, and does not care for the actual HTTP status code. (It does not notice if it's a temporary redirect or a permanent.)
If you want more direct control over your http queries I suggest using curl.
来源：https://stackoverflow.com/questions/5526209/does-phps-file-get-contents-cache-a-301-status-code