Brief Answers on the following

Dear Experts

I have an interview coming up in next week with profile of C/C++, Perl, Oracle, PL/SQL and Unix
I can manage the other technologies except Strong command on Unix since I have been using Windows heavily .
For Technical Interview I have a sample collection of Intermediate to Tough Question on Unix which I wud like to share with you.
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How do you list the files in an UNIX directory while also showing hidden files?
How do you execute a UNIX command in the background?
What UNIX command will control the default file permissions when files are created?
Explain the read, write, and execute permissions on a UNIX directory.
What is the difference between a soft link and a hard link?
Give the command to display space usage on the UNIX file system.
Explain iostat, vmstat and netstat.
How would you change all occurrences of a value using VI?
Give two UNIX kernel parameters that effect an Oracle install
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I would really appriacite your expertise to  solve above questions.
Thank you for your time
Ronan