Having migrated to Linux from Windows, I would like to find an alternative software to Winmerge or rather learn command line tools to compare and sync two folders on Linux. I would be grateful if you could tell me how to do the following tasks on the command line... (I have studied diff and rsync, but I still need some help.)
We have two folders: "/home/user/A" and "/home/user/B"
Folder A is the place where regular files and folders are saved and folder B is a backup folder that serves as a complete mirror of folder A. (Nothing is directly saved or modified by the user in folder B.)
My questions are:
How to list files that exist only in folder B? (E.g. the ones deleted from folder A since the last synchronization.)
How to copy files that exist in only folder B back into folder A?
How to list files that exist in both folders but have different timestamps or sizes? (The ones that have been modified in folder A since last synronization. I would like to avoid using checksums, because there are tens of thousands of files and it'd make the process too slow.)
How to make an exact copy of folder A into folder B? I mean, copy everything from folder A into folder B that exists only in folder A and delete everything from folder B that exists only in folder B, but without touching the files that are the same in both folders.