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Last tested: Jul 3, 2018
Most likely it means that you downloaded the html version of the startup script, as opposed to the actual startup script. Instead download the actual startup script.
Another startup error on a windows machine is if you download it on a windows host and then copy it to your looker linux host. In that case you'll see
-bash: ./looker: /bin/sh^M: bad interpreter: No such file or directory
In that case, you'll want to make sure you downloaded it directly on your linux host.
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