wget:检查文件时间戳和覆盖 [英] wget: Checking for file timestamp and overwriting

问题描述

我怎样才能让 wget 做到这一点:

从 x 位置下载文件，仅当文件的本地副本具有比 x 上的文件时间戳旧的时间戳时.这意味着，它应该从给定的位置下载文件，前提是文件有更新版本.

如果有更新版本的文件，wget 应该覆盖该文件.

可以这样做吗?

解决方案

听起来您正在寻找 wget 的时间戳功能:http://www.gnu.org/software/wget/manual/wget.html#Time_002dStamping

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假设你想下载一个文件以便它保持其日期修改.

wget -S http://www.gnu.ai.mit.edu/

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一个简单的 ls -l 显示本地文件上的时间戳等于当前文件的状态Last-Modified 标头，由返回服务器.如您所见，时间戳信息被保留本地，即使没有-N"(至少对于 http).

几天后，你想wget 检查远程文件是否有已更改，如果已更改，请下载.

wget -N http://www.gnu.ai.mit.edu/

How 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than that of the file's time stamp on x. That means, it should download a file from a given location, only if there is a newer version of the file.

In case there is a newer version of the file, wget should overwrite the file.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?

解决方案

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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