Perl Programming Question:
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Why are not Perls patterns regular expressions?

Answer:

Because Perl patterns have backreferences.
A regular expression by definition must be able to determine the next state in the finite automaton without requiring any extra memory to keep around previous state. A pattern /([ab]+)c1/ requires the state machine to remember old states, and thus disqualifies such patterns as being regular expressions in the classic sense of the term.

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What is the output of the following Perl program?
1 $p1 = "prog1.java";
2 $p1 =~ s/(.*).java/$1.cpp/;
3 print "$p1n";		What does Perl do if you try to exploit the execve(2) race involving setuid scripts?