If you type the command cat dog & > cat what would you see on your display? Choose one:
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Any error messages only.
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the contents of the file dog and any error messages.
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Nothing as all output is saved to the file cat.
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The contents of the file dog.
The command 'cat dog &' runs cat in the background, and the '> cat' redirects stdout to file 'cat'. However, since the command runs in the background with '&', the redirection applies after backgrounding. The file contents are displayed on stdout (the display), while any error messages would still go to stderr. The background process with file redirection means stdout goes to file, but the question tests understanding that contents are still displayed.
In POSIX/bash shell grammar, & is a command-list separator (like ;) that terminates the preceding simple command asynchronously, at the same precedence level as separating whole commands — it does not extend into a following redirection. So cat dog & > cat parses as two separate list items: (1) cat dog & — run cat dog in the background with its stdout going to the normal controlling terminal, since no redirection is attached to this command; and (2) > cat — a redirection with no command at all, which merely opens (creates/truncates) the file cat for writing and writes nothing to it. Empirically verified: running this exact construct prints the contents of dog to the terminal, and the file cat ends up 0 bytes. So the visible output is the contents of file dog (plus a job-control line), not "nothing".