Once a shell variable has been created, how can the variable be removed from the environment?

Which command will show you the contents of a gzip compressed tar archive?

What command line redirection characters instruct the shell to read from the current input source until a
specific word, on a separate line and without any trailing spaces, is reached?

Which of the following commands will send output from the program myapp to both standard output (stdout)
and the file file1.log?

What is the purpose of the xargs command?

Which vi command will change modes so that text can be entered by typing in the keyboard?

Which signal is sent to a suspended process in order to have it resume execution?

What does the ?symbol mean in the following grep regular expression:
grep ‘^d[aei]\\?d$’ /usr/share/dict/words

In the vi editor, which of the following commands will copy the current line into the vi buffer?

Which of the following commands will produce the following output?
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1255 4.4 0.9 60716 34824
tty7 Ss+ 09:25 19:04 /usr/bin/X :0 – root 2016 0.0 0.0 1792 560 tty1 Ss+ 09:26 0:00 /sbin/getty -8 matt 5204
0.0 0.1 6320 3696 pts/4 Ss 13:12 0:00 bash matt 5219 0.0 0.0 3988 1624 pts/4 S+ 13:12 0:00 man bash
matt 5229 0.0 0.0 3584 932 pts/4 S+ 13:12 0:00 pager -s matt 6768 0.0 0.1 10504 3880 pts/2 S+ 15:11
0:00 vi README.txt