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So, this was posted before, but you had to actually read the article after following a link. Try this command, it will open the default file manager on many different versions of Linux. You don't have to know the name of the program itself (nautilus, nemo, etc...)sudo xdg-open .
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More usage of the xdg-open command. It appears that it either opens a file or URL with the default program. Since we are using it with a . after the command it seems to just open the file manager by default when nothing except a period is specified which is handy. The link says they don't recommend running it as root, but it works to get the file manager open with sudo.