Perl Scripting Interview Questions: Practical Answers with Runnable Examples

These are common Perl interview questions for entry-level automation and operations roles. This revision provides clear, practical answers with examples you can run and adapt for real scripting tasks.

Originally published on 2010-08-24; fully revised and updated.

Question 1: Which standard Perl modules are useful, and why use them?

Interviewers often want to see whether you can choose maintainable, portable solutions instead of ad-hoc code. In Perl, that usually means using well-known pragmas and core modules where they improve safety, readability, or cross-platform behavior.

Question 2: Check for at least two command-line arguments

A compact interview-safe answer is to validate @ARGV count and fail fast with a helpful usage message.

#!/usr/bin/perl
use strict;
use warnings;

die "Error: need at least two arguments\nUsage: $0 arg1 arg2 [more]\n"
    unless @ARGV >= 2;

my ($arg1, $arg2) = @ARGV[0, 1];
print "arg1=$arg1 arg2=$arg2\n";Code language: PHP (php)

Question 3: Find the number of elements in an array

The idiomatic way is scalar @array. You may also see $#array + 1, but scalar @array is usually clearer.

#!/usr/bin/perl
use strict;
use warnings;

my @items = qw(cpu memory disk network);
my $count = scalar @items;

print "Element count: $count\n";Code language: PHP (php)

Question 4: Regex to match the last directory in a full path

Given /fee/fi/fo/fum.txt, the expected match is fo. One regex approach is to capture the directory right before the file name.

#!/usr/bin/perl
use strict;
use warnings;

my $path = '/fee/fi/fo/fum.txt';
my ($last_dir) = $path =~ m{(?:^|[\\/])([^\\/]+)[\\/][^\\/]+$};

if (defined $last_dir) {
    print "$last_dir\n";  # fo
} else {
    print "No match\n";
}Code language: PHP (php)

For production scripts, path modules are often easier to maintain than complex regex-only parsing, especially when path formats vary.

Question 5: Print machine host name without system commands

Use Sys::Hostname to avoid shelling out. This is the expected approach in many interview settings.

#!/usr/bin/perl
use strict;
use warnings;
use Sys::Hostname;

my $host = hostname();
print "$host\n";Code language: PHP (php)

Question 6: Check whether a directory exists (path passed as argument)

Use Perl file test operators. For directories, -d is the direct check.

#!/usr/bin/perl
use strict;
use warnings;

my $dir = shift @ARGV
    or die "Usage: $0 /path/to/directory\n";

if (-d $dir) {
    print "Directory exists: $dir\n";
} else {
    print "Directory does not exist: $dir\n";
}Code language: PHP (php)

A fast workflow for solving Perl interview scripting tasks

In interviews, a repeatable approach helps you avoid small mistakes and communicate clearly while coding.

flowchart TD
    A[Read the prompt carefully] --> B[Identify required input]
    B --> C{Input from ARGV}
    C -- yes --> D[Validate argument count]
    C -- no --> E[Set sample input in script]
    D --> F[Pick core module or built in]
    E --> F
    F --> G[Write minimal working code]
    G --> H[Print clear success and error output]

Best practices for Perl interview answers

• Start scripts with use strict; and use warnings;.
• Validate inputs early and show a clear usage message.
• Prefer core modules when they improve portability or readability.
• Print deterministic output so the interviewer can verify behavior quickly.
• Explain tradeoffs briefly (for example, regex solution vs path module solution).

Rajesh Kumar

I’m Rajesh Kumar, a DevOps, SRE, DevSecOps, Cloud, and Platform Engineering expert passionate about sharing practical knowledge, real-world experiences, and industry best practices. I have worked at Cotocus and regularly write about technology, travel, investing, health, product reviews, and digital marketing through my various platforms.

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