PERL Interview Questions & Answers
Showing 10 of 25 questions
PERL technical interview questions and answers are useful for candidates applying for scripting, automation, and system administration roles. PERL is widely used in text processing, network programming, automation scripts, and backend development, making it a common interview topic in IT companies. Recruiters from TCS, Wipro, Infosys, Cognizant, Capgemini, and Accenture often test candidates on PERL basics, syntax, regular expressions, arrays, hashes, file handling, subroutines, and modules. This guide provides clear explanations and examples for the most important PERL interview questions. Whether you are preparing for campus placements or experienced-level interviews, this resource will help you strengthen your scripting knowledge. You can also download PERL interview PDFs and practice mock questions to improve your performance.
Showing 10 of 25 questions
1. Why do you use Perl?
Perl is a powerful free interpreter.
Perl is portable, flexible and easy to learn.
2. How do I set environment variables in Perl programs?
you can just do something like this:
$path = $ENV{'PATH'};
As you may remember, "%ENV" is a special hash in Perl that contains the value of all your environment variables.
Because %ENV is a hash, you can set environment variables just as you'd set the value of any Perl hash variable. Here's how you can set your PATH variable to make sure the following four directories are in your path::
$ENV{'PATH'} = '/bin:/usr/bin:/usr/local/bin:/home/yourname/bin';
3. Which of these is a difference between C++ and Perl?
Perl can have objects whose data cannot be accessed outside its class, but C++ cannot.
Perl can use closures with unreachable private data as objects, and C++ doesn't support closures. Furthermore, C++ does support pointer arithmetic via `int *ip = (int*)&object', allowing you do look all over the object. Perl doesn't have pointer arithmetic. It also doesn't allow `#define private public' to change access rights to foreign objects. On the other hand, once you start poking around in /dev/mem, no
4. What is Perl one-liner?
There are two ways a Perl script can be run:
--from a command line, called one-liner, that means you type and execute immediately on the command line. You'll need the -e option to start like "C:\ %gt perl -e "print \"Hello\";". One-liner doesn't mean one Perl statement. One-liner may contain many statements in one line.
--from a script file, called Perl program.
5. Assuming both a local($var) and a my($var) exist, what's the difference between ${var} and ${"var"}?
${var} is the lexical variable $var, and ${"var"} is the dynamic variable $var.
Note that because the second is a symbol table lookup, it is disallowed under `use strict "refs"'. The words global, local, package, symbol table, and dynamic all refer to the kind of variables that local() affects, whereas the other sort, those governed by my(), are variously knows as private, lexical, or scoped variable.
6. What happens when you return a reference to a private variable?
Perl keeps track of your variables, whether dynamic or otherwise, and doesn't free things before you're done using them.
7. What are scalar data and scalar variables?
Perl has a flexible concept of data types. Scalar means a single thing, like a number or string. So the Java concept of int, float, double and string equals to Perl\'s scalar in concept and the numbers and strings are exchangeable. Scalar variable is a Perl variable that is used to store scalar data. It uses a dollar sign $ and followed by one or more alphanumeric characters or underscores. It is case sensitive.
8. Why aren't Perl's patterns regular expressions?
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]+)c\1/ requires the state machine to remember old states, and thus disqualifies such patterns as being regular expressions in the classic sense of the term.
9. What does Perl do if you try to exploit the execve(2) race involving setuid scripts?
Sends mail to root and exits.
It has been said that all programs advance to the point of being able to automatically read mail. While not quite at that point (well, without having a module loaded), Perl does at least automatically send it.
10. How do you print out the next line from a filehandle with all its bytes reversed?
print scalar reverse scalar
Surprisingly enough, you have to put both the reverse and the into scalar context separately for this to work.