Today I discovered an article explaining Linux file system timestamps: Linux File Timestamps Explained: atime, mtime, and ctime; and a good thing too, because I always thought ‘ctime’ was ‘create time’, but not so! Turns out that ‘ctime’ is ‘change time’, similar to ‘mtime’ but apparently cannot be set from userspace. My investigations were prompted by my investigations info how `borg create` identified changed files.