Linux OS Shell Question: Download Linux Shell PDF

What will be output of following command:
$ echo "The process id is" $$$$

a) The process id is $$
b) The process id is $<pid>$<pid>
c) The process id is <pid><pid>
d) The process id is $$$$

c) The process id is <pid><pid>

Previous Question	Next Question
Create a new file "new.txt" that is a concatenation of "file1.txt" and "file2.txt"? a) cp file.txt file2.txt new.txt b) cat file1.txt file2.txt > new.txt c) mv file[12].txt new.txt d) ls file1.txt file2.txt \| new.txt	What is the return value ($?) of this code: os = Unix [$osName = UnixName] && exit 2 [${os}Name = UnixName] && exit 3 a) 0 b) 1 c) 2 d) 3