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开发者_如何学Go Improve this questionHow can I get wget
to do this:
Download a file from a location say x
, only if the local copy of the file has an older time stamp than that of the file's time stamp on x
. That means, it should download a file from a given location, only if there is a newer version of the file.
In case there is a newer version of the file, wget
should overwrite the file.
Is it possible to do this?
Sounds like you're looking for the TimeStamping functionality of wget: http://www.gnu.org/software/wget/manual/wget.html#Time_002dStamping
Say you would like to download a file so that it keeps its date of modification.
wget -S http://www.gnu.ai.mit.edu/
A simple ls -l shows that the time stamp on the local file equals the state of the Last-Modified header, as returned by the server. As you can see, the time-stamping info is preserved locally, even without ‘-N’ (at least for http).
Several days later, you would like Wget to check if the remote file has changed, and download it if it has.
wget -N http://www.gnu.ai.mit.edu/
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