I'm using wget mirror option to mirror a complete website
wget -mk https://test.com
When I stop wget and resume it afterwards with the same command, it will keep issuing HEAD-commands for all the files already downloaded. This is to check if the files have changed since the last download and retrieve them again if the file on the server is newer. I would like to turn off this functionality, meaning: If a local file already exists, wget should use the local file always and not even issue a HEAD-command to validate modification time or filesize. Is this possible?
No, you cannot. There is no switch in Wget as of this writing that will allow you to skip testing the local files. And there is a very good reason for that. If Wget did not validate each file again, one or both of these two issues will occur:
The last file that was being downloaded is now incomplete and corrupt. But you have no indication of this or which file it was. This also means that Wget will not be able to parse and follow any links from this file. So you will likely end up with a partial mirror and nothing to tell you that.
Some of the files changed on the remote end between your last attempt and the current one. Without validating the modification times again, what you're getting is an inconsistent mirror. Since the half the mirror is old and other half is new, this is new, there could be all sorts of interesting issues that result out of this.
And anyways, a HEAD request is very fast, since it needs very little bandwidth. So I don't see why that would be the choke point in any pipeline.