Download the tgz archive and save to disk.
The only catch is that you have to be an administrative user with access to the root of the filesystem (i.e., you have to be an sudoer). Installing MacQIIME should hopefully be pretty simple in any Mac with OS 10.7 and up. # Rename your old backup of macqiime 1.9.0 to /macqiime: # Move the new macqiime 1.9.1 out of the way: # Reverting back to your old install of MacQIIME 1.9.0 for some reason Then, in the future, if you ever want to revert back to your old install of MacQIIME 1.9.0, for any reason, you can move things back like this: # Backing up your old MacQIIME 1.9.0 installation Anything you leave in the /macqiime directory will be deleted by the new installation, so if you've added any files to the old /macqiime directory you will want to make some copies of them or move them! To move the whole directory to a new location, you can just use the mv command in the Terminal. But, backing things up instead of deleting them is always a safe way to go. If you have an old/previous version of macqiime installed, you don't really have to back it up, because you can always just install it again from the archives. They shouldn't fight with each other, as long as you only have one of them sourced at any given time. It is also possible to have MacQIIME 1.9.1 and QIIME 2 installed at the same time, if you really want to.