From 764c7423b65d37d1a8cd913cbe715fc346ac2248 Mon Sep 17 00:00:00 2001
From: Adrian <59370927+adrianfusco@users.noreply.github.com>
Date: Sat, 20 Nov 2021 01:12:20 +0100
Subject: [PATCH] Update/move perl section (#187)
* New questions and spell check (#181)
Added new questions related with KVM, Libvirt and DNF
* Create a new perl folder and move the content of the actual section
---
README.md | 514 +--------------------------------------
exercises/perl/README.md | 511 ++++++++++++++++++++++++++++++++++++++
2 files changed, 512 insertions(+), 513 deletions(-)
create mode 100644 exercises/perl/README.md
diff --git a/README.md b/README.md
index aa8b8d5..6d33889 100644
--- a/README.md
+++ b/README.md
@@ -74,7 +74,7 @@
Puppet |
Distributed |
Questions you can ask |
- 
Perl |
+
Perl |
@@ -5034,518 +5034,6 @@ Output: 3
[Golang container/heap package](https://golang.org/pkg/container/heap/)
-## Perl
-
-### Perl Self Assessment
-
-
-What is Perl?
-
-From the official [docs](https://perldoc.perl.org/):
-
-"Perl officially stands for Practical Extraction and Report Language, except when it doesn't."
-
-It's a general purpose programming language developed for manipulating texts mainly. It has been used to perform system administration tasks, networking, building websites and more.
-
-
-
-What data types Perl has? And how can we define it?
-
-- Scalar: This is a simple variable that stores single data items. It can be a string, number or reference.
-
-```
-my $number = 5;
-```
-
-- Arrays: This is a list of scalars.
-
-```
-my @numbers = (1, 2, 3, 4, 5);
-# or using the `qw` keyword (quote word):
-my @numbers = qw/1 2 3 4 5/;
-# '/' can be another symbol, e.g qw@1 2 3 4 5@
-```
-
-- Hashes (or associative arrays): This is an unordered collection of key-value pairs. We can access to a hash using the keys.
-
-```
-my %numbers = (
- First => '1',
- Second => '2',
- Third => '3'
-);
-```
-
-
-
-
-How can you access to a hash value, add and delete a key/value pair and modify a hash?
-
-```
-my %numbers = (
- 'First' => '1',
- 'Second' => '2',
- 'Third' => '3'
-);
-```
-
-- Access:
-
-```
-print($numbers{'First'});
-```
-
-- Add:
-
-```
-$numbers{'Fourth'} = 4;
-```
-
-- Delete:
-
-```
-delete $numbers{'Third'};
-```
-
-- Modify:
-
-```
-$numbers{'Fifth'} = 6;
-$numbers{'Fifth'} = 5;
-```
-
-
-
-
-How can you iterate an array? And a hash?
-
-- Array:
-
-```
-my @numbers = qw/1 2 3 4 5/;
-
-# Using `$_` that represents the current iteration in a loop. It starts from index array 0 until the last index.
-foreach (@numbers) {
- print($_);
-}
-# Output: 12345
-
-
-# "$#" returns the max index of an array. That's the reason because we can iterate accesing to the array from the index 0 to the max index.
-for my $i (0..$#numbers) {
- print($numbers[$i]);
-}
-# Output: 12345
-
-
-# Using the `map` keyword:
-print map {$_} @numbers;
-# Output: 12345
-
-# Using `while`. We should take care with this option. When we use `shift` we're deleting the first element of the array and assigning it to the `element` variable.
-# After this `loop` the `numbers` array will not have elements.
-while (my $element = shift(@numbers)) {
- print($element);
-}
-# Output: 12345
-```
-
-- Hashes:
-
- ```
- my %capital_cities = (
- 'Madrid' => 'Spain',
- 'Rome' => 'Italy',
- 'Berlin' => 'Germany'
-);
-
-# Iterate and get the `keys`:
-foreach my $city (keys %capital_cities) {
- print($city . "\n");
-}
-# Iterate and get the `values`:
-foreach my $country (values %capital_cities) {
- print($country . "\n");
-}
-
-# Iterate and get the values and keys (first option):
-foreach my $city (keys %capital_cities) {
- print("City: $city - Country: $capital_cities{$city}" . "\n");
-}
-
-# Iterate and get the values and keys (first option):
-while(my ($city, $country) = each %capital_cities) {
- print("City: $city - Country: $capital_cities{$city}" . "\n");
-}
-```
-
-
-
-
-What is a Perl subroutine? How to define it?
-
-It's the perl model for user defined functions (this is also called function like other programming languages). We can define a subroute with the keyword `sub`.
-
-```
-sub hello {
- print "hello";
-}
-```
-
-
-
-
-Describe the different ways to receive parameters in a subroutine
-
-- List assignment: Using the `@_` array. It's a list with the elements that are being passed as parameters.
-
-```
-sub power {
- my ($b, $e) = @_;
- return $b ** $e;
-}
-
-&power(2, 3);
-```
-
-- Individual assigment: We should access to every element of the `@_` array. It starts from zero.
-
-```
-sub power {
- my $b = $_[0];
- my $e = $_[1];
- return $b ** $e;
-}
-
-&power(2, 3);
-```
-
-- Using `shift` keyword: It's used to remove the first value of an array and it's returned.
-
-```
-sub power {
- my $b = shift;
- my $3 = shift;
- return $b ** $e;
-}
-
-&power(2, 3);
-```
-
-
-[Source](https://stackoverflow.com/a/21465275/12771230)
-
-We can also read the best way in the same S.O answer.
-
-
-
-
-What is lexical and dynamic scoping?
-
-
-
-How to apply referencing and dereferencing?
-
-
-
-Does Perl have conventions?
-
-You can check [perlstyle](https://perldoc.perl.org/perlstyle)
-
-
-
-
-What is Perl POD? Can you code an example?
-
-From the official [docs](https://perldoc.perl.org/perlpod):
-
-"Pod is a simple-to-use markup language used for writing documentation for Perl, Perl programs, and Perl modules."
-
-```
-=item
- This function returns the factorial of a number.
- Input: $n (number you wanna calculate).
- Output: number factorial.
-=cut
-sub factorial {
- my ($i, $result, $n) = (1, 1, shift);
- $result = $result *= $i && $i++ while $i <= $n;
- return $result;
-}
-```
-
-
-
-### Perl Regex
-
-
-Check if the word `electroencefalografista` exists in a string
-
-```
-my $string = "The longest accepted word by RAE is: electroencefalografista";
-if ($string =~ /electroencefalografista/) {
- print "Match!";
-}
-```
-
-
-
-Check if the word `electroencefalografista` does not exists in a string
-
-```
-my $string = "The longest not accepted word by RAE is: Ciclopentanoperhidrofenantreno";
-if ($string !~ /electroencefalografista/) {
- print "Does not match!";
-}
-```
-
-
-
-
-Replace the word `amazing`
-
-```
-my $string = "Perl is amazing!";
-$string =~ s/amazing/incredible/;
-print $string;
-# Perl is incredible!
-```
-
-
-
-Extract `hh:mm:ss` with capturing group `()` in the following datetime
-
-```
-my $date = "Fri Nov 19 20:09:37 CET 2021";
-my @matches = $date =~ /(.*)(\d{2}:\d{2}:\d{2})(.*)/;
-print $matches[1];
-# Output: 20:09:37
-```
-
-
-
-Extract all the elements that are numbers in an array
-
-```
-my @array = ('a', 1, 'b', 2, 'c', 3);
-my @numbers = grep (/\d/, @array); # Note: \d involves more digits than 0-9
-map {print $_ . "\n" } @numbers;
-```
-
-
-
-
-Print all the linux system users that starts with d or D
-
-- With a Perl one liner :D
-```
-open(my $fh, '<', '/etc/passwd');
-my @user_info = <$fh>;
-map { print $& . "\n" if $_ =~ /^d([^:]*)/ } @user_info;
-close $fh;
-```
-
-- Avoiding one-liners
-
-```
-foreach my $user_line (@user_info) {
- if ($user_line =~ /^d([^:]*)/) {
- print $& . "\n";
- }
-}
-```
-
-
-
-### Perl Files Handle
-
-
-Mention the different modes in File Handling
-
-- Read only: `<`
-- Write mode. It creates the file if doesn't exist: `>`
-- Append mode. It creates the file if doesn't exist: `>>`
-- Read and write mode: `+<`
-- Read, clear and write mode. It creates the file if doesn't exist: `+>`
-- Read and append. It creates the file if doesn't exist: `+>>`
-
-
-
-
-How to write into a file?
-
-```
-# We can use:
-# '>' Write (it clears a previous content if exists).
-# '>>' Append.
-open(my $fh, '>>', 'file_name.ext') or die "Error: file can't be opened";
-print $fh "writing text...\n";
-close($fh);
-```
-
-
-
-How can you read a file and print every line?
-
-```
-open(my $fh, '<', 'file_to_read.ext') or die "Error: file can't be opened";
-my @file = <$fh>;
-foreach my $line (@file) {
- print $line;
-}
-```
-
-We can use the file handle without assigning it to an array:
-
-```
-open(my $fh, '<', 'file_to_read.ext') or die "Error: file can't be opened";
-
-foreach my $line (<$fh>) {
- print $line;
-}
-```
-
-
-
-### Perl OOP
-
-
-Does Perl have support for OOP?
-
-From the official [docs](https://perldoc.perl.org/perlootut):
-
-"By default, Perl's built-in OO system is very minimal, leaving you to do most of the work."
-
-
-
-
-What is the purpose of the bless function?
-
-The function os the `bless` function is used to turning a plain data structure into an object.
-
-
-
-
-How to create a Perl class? How can you call a method?
-
-- Let's create the package: `Example.pm`
-
-```
-package Example;
-
-sub new {
- my $class = shift;
- my $self = {};
- bless $self, $class;
- return $self;
-}
-
-sub is_working {
- print "Working!";
-}
-
-1;
-```
-
-- Now we can instance the `Example` class and call `is_working` method:
-
-```
-my $e = new Example();
-$e->is_working();
-# Output: Working!
-```
-
-
-
-
-Does Perl have inheritance? What is the `SUPER` keyword?
-
-Yes, Perl supports inheritance. We can read about it in the official [docs](https://perldoc.perl.org/perlobj#Inheritance).
-We also can read about `SUPER` keyword that is used to call a method from the parent class. It gives an example about how we can apply inheritance.
-
-
-
-Does Perl have polymorphism? What is method overriding?
-
-Yes, it has polymorphism. In fact method overriding is a way to apply it in Perl.
-
-Method overriding in simple words appears when we have a class with a method that already exist in a parent class.
-
-Example:
-
-```
-package A;
-
-sub new { return bless {}, shift; };
-sub printMethod { print "A\n"; };
-
-package B;
-
-use parent -norequire, 'A';
-
-sub new { return bless {}, shift; };
-sub printMethod { print "B\n"; };
-
-my $a = A->new();
-my $b = B->new();
-
-A->new()->printMethod();
-B->new()->printMethod();
-
-# Output:
-# A
-# B
-```
-
-
-
-
-How can you call a method of an inherited class?
-
-```
-# Class `A` with `printA` method.
-package A;
-
-sub new { return bless {}, shift; };
-sub printA { print "A"; };
-
-# Class `B` that extends or use the parent class `A`.
-package B;
-
-use parent -norequire, 'A';
-
-sub new { return bless {}, shift; };
-
-# Instance class `B` allows call the inherated method
-my $b = B->new();
-$b->printA();
-```
-
-
-### Perl OS
-
-
-What is Perl Open3?
-
-
-### Perl Packages & Modules
-
-
-What is a Perl package? And a module?
-
-
-
-What is the difference between .pl and .pm extensions?
-
-
-
-What is cpan? And cpanm?
-
-
-
-How can you install a Perl module?
-
-
## Mongo
diff --git a/exercises/perl/README.md b/exercises/perl/README.md
new file mode 100644
index 0000000..546e435
--- /dev/null
+++ b/exercises/perl/README.md
@@ -0,0 +1,511 @@
+## Perl
+
+### Perl Self Assessment
+
+
+What is Perl?
+
+From the official [docs](https://perldoc.perl.org/):
+
+"Perl officially stands for Practical Extraction and Report Language, except when it doesn't."
+
+It's a general purpose programming language developed for manipulating texts mainly. It has been used to perform system administration tasks, networking, building websites and more.
+
+
+
+What data types Perl has? And how can we define it?
+
+- Scalar: This is a simple variable that stores single data items. It can be a string, number or reference.
+
+```
+my $number = 5;
+```
+
+- Arrays: This is a list of scalars.
+
+```
+my @numbers = (1, 2, 3, 4, 5);
+# or using the `qw` keyword (quote word):
+my @numbers = qw/1 2 3 4 5/;
+# '/' can be another symbol, e.g qw@1 2 3 4 5@
+```
+
+- Hashes (or associative arrays): This is an unordered collection of key-value pairs. We can access to a hash using the keys.
+
+```
+my %numbers = (
+ First => '1',
+ Second => '2',
+ Third => '3'
+);
+```
+
+
+
+
+How can you access to a hash value, add and delete a key/value pair and modify a hash?
+
+```
+my %numbers = (
+ 'First' => '1',
+ 'Second' => '2',
+ 'Third' => '3'
+);
+```
+
+- Access:
+
+```
+print($numbers{'First'});
+```
+
+- Add:
+
+```
+$numbers{'Fourth'} = 4;
+```
+
+- Delete:
+
+```
+delete $numbers{'Third'};
+```
+
+- Modify:
+
+```
+$numbers{'Fifth'} = 6;
+$numbers{'Fifth'} = 5;
+```
+
+
+
+
+How can you iterate an array? And a hash?
+
+- Array:
+
+```
+my @numbers = qw/1 2 3 4 5/;
+
+# Using `$_` that represents the current iteration in a loop. It starts from index array 0 until the last index.
+foreach (@numbers) {
+ print($_);
+}
+# Output: 12345
+
+
+# "$#" returns the max index of an array. That's the reason because we can iterate accesing to the array from the index 0 to the max index.
+for my $i (0..$#numbers) {
+ print($numbers[$i]);
+}
+# Output: 12345
+
+
+# Using the `map` keyword:
+print map {$_} @numbers;
+# Output: 12345
+
+# Using `while`. We should take care with this option. When we use `shift` we're deleting the first element of the array and assigning it to the `element` variable.
+# After this `loop` the `numbers` array will not have elements.
+while (my $element = shift(@numbers)) {
+ print($element);
+}
+# Output: 12345
+```
+
+- Hashes:
+
+ ```
+ my %capital_cities = (
+ 'Madrid' => 'Spain',
+ 'Rome' => 'Italy',
+ 'Berlin' => 'Germany'
+);
+
+# Iterate and get the `keys`:
+foreach my $city (keys %capital_cities) {
+ print($city . "\n");
+}
+# Iterate and get the `values`:
+foreach my $country (values %capital_cities) {
+ print($country . "\n");
+}
+
+# Iterate and get the values and keys (first option):
+foreach my $city (keys %capital_cities) {
+ print("City: $city - Country: $capital_cities{$city}" . "\n");
+}
+
+# Iterate and get the values and keys (first option):
+while(my ($city, $country) = each %capital_cities) {
+ print("City: $city - Country: $capital_cities{$city}" . "\n");
+}
+```
+
+
+
+
+What is a Perl subroutine? How to define it?
+
+It's the perl model for user defined functions (this is also called function like other programming languages). We can define a subroute with the keyword `sub`.
+
+```
+sub hello {
+ print "hello";
+}
+```
+
+
+
+
+Describe the different ways to receive parameters in a subroutine
+
+- List assignment: Using the `@_` array. It's a list with the elements that are being passed as parameters.
+
+```
+sub power {
+ my ($b, $e) = @_;
+ return $b ** $e;
+}
+
+&power(2, 3);
+```
+
+- Individual assigment: We should access to every element of the `@_` array. It starts from zero.
+
+```
+sub power {
+ my $b = $_[0];
+ my $e = $_[1];
+ return $b ** $e;
+}
+
+&power(2, 3);
+```
+
+- Using `shift` keyword: It's used to remove the first value of an array and it's returned.
+
+```
+sub power {
+ my $b = shift;
+ my $3 = shift;
+ return $b ** $e;
+}
+
+&power(2, 3);
+```
+
+
+[Source](https://stackoverflow.com/a/21465275/12771230)
+
+We can also read the best way in the same S.O answer.
+
+
+
+
+What is lexical and dynamic scoping?
+
+
+
+How to apply referencing and dereferencing?
+
+
+
+Does Perl have conventions?
+
+You can check [perlstyle](https://perldoc.perl.org/perlstyle)
+
+
+
+
+What is Perl POD? Can you code an example?
+
+From the official [docs](https://perldoc.perl.org/perlpod):
+
+"Pod is a simple-to-use markup language used for writing documentation for Perl, Perl programs, and Perl modules."
+
+```
+=item
+ This function returns the factorial of a number.
+ Input: $n (number you wanna calculate).
+ Output: number factorial.
+=cut
+sub factorial {
+ my ($i, $result, $n) = (1, 1, shift);
+ $result = $result *= $i && $i++ while $i <= $n;
+ return $result;
+}
+```
+
+
+
+### Perl Regex
+
+
+Check if the word `electroencefalografista` exists in a string
+
+```
+my $string = "The longest accepted word by RAE is: electroencefalografista";
+if ($string =~ /electroencefalografista/) {
+ print "Match!";
+}
+```
+
+
+
+Check if the word `electroencefalografista` does not exists in a string
+
+```
+my $string = "The longest not accepted word by RAE is: Ciclopentanoperhidrofenantreno";
+if ($string !~ /electroencefalografista/) {
+ print "Does not match!";
+}
+```
+
+
+
+
+Replace the word `amazing`
+
+```
+my $string = "Perl is amazing!";
+$string =~ s/amazing/incredible/;
+print $string;
+# Perl is incredible!
+```
+
+
+
+Extract `hh:mm:ss` with capturing group `()` in the following datetime
+
+```
+my $date = "Fri Nov 19 20:09:37 CET 2021";
+my @matches = $date =~ /(.*)(\d{2}:\d{2}:\d{2})(.*)/;
+print $matches[1];
+# Output: 20:09:37
+```
+
+
+
+Extract all the elements that are numbers in an array
+
+```
+my @array = ('a', 1, 'b', 2, 'c', 3);
+my @numbers = grep (/\d/, @array); # Note: \d involves more digits than 0-9
+map {print $_ . "\n" } @numbers;
+```
+
+
+
+
+Print all the linux system users that starts with d or D
+
+- With a Perl one liner :D
+```
+open(my $fh, '<', '/etc/passwd');
+my @user_info = <$fh>;
+map { print $& . "\n" if $_ =~ /^d([^:]*)/ } @user_info;
+close $fh;
+```
+
+- Avoiding one-liners
+
+```
+foreach my $user_line (@user_info) {
+ if ($user_line =~ /^d([^:]*)/) {
+ print $& . "\n";
+ }
+}
+```
+
+
+
+### Perl Files Handle
+
+
+Mention the different modes in File Handling
+
+- Read only: `<`
+- Write mode. It creates the file if doesn't exist: `>`
+- Append mode. It creates the file if doesn't exist: `>>`
+- Read and write mode: `+<`
+- Read, clear and write mode. It creates the file if doesn't exist: `+>`
+- Read and append. It creates the file if doesn't exist: `+>>`
+
+
+
+
+How to write into a file?
+
+```
+# We can use:
+# '>' Write (it clears a previous content if exists).
+# '>>' Append.
+open(my $fh, '>>', 'file_name.ext') or die "Error: file can't be opened";
+print $fh "writing text...\n";
+close($fh);
+```
+
+
+
+How can you read a file and print every line?
+
+```
+open(my $fh, '<', 'file_to_read.ext') or die "Error: file can't be opened";
+my @file = <$fh>;
+foreach my $line (@file) {
+ print $line;
+}
+```
+
+We can use the file handle without assigning it to an array:
+
+```
+open(my $fh, '<', 'file_to_read.ext') or die "Error: file can't be opened";
+
+foreach my $line (<$fh>) {
+ print $line;
+}
+```
+
+
+
+### Perl OOP
+
+
+Does Perl have support for OOP?
+
+From the official [docs](https://perldoc.perl.org/perlootut):
+
+"By default, Perl's built-in OO system is very minimal, leaving you to do most of the work."
+
+
+
+
+What is the purpose of the bless function?
+
+The function os the `bless` function is used to turning a plain data structure into an object.
+
+
+
+
+How to create a Perl class? How can you call a method?
+
+- Let's create the package: `Example.pm`
+
+```
+package Example;
+
+sub new {
+ my $class = shift;
+ my $self = {};
+ bless $self, $class;
+ return $self;
+}
+
+sub is_working {
+ print "Working!";
+}
+
+1;
+```
+
+- Now we can instance the `Example` class and call `is_working` method:
+
+```
+my $e = new Example();
+$e->is_working();
+# Output: Working!
+```
+
+
+
+
+Does Perl have inheritance? What is the `SUPER` keyword?
+
+Yes, Perl supports inheritance. We can read about it in the official [docs](https://perldoc.perl.org/perlobj#Inheritance).
+We also can read about `SUPER` keyword that is used to call a method from the parent class. It gives an example about how we can apply inheritance.
+
+
+
+Does Perl have polymorphism? What is method overriding?
+
+Yes, it has polymorphism. In fact method overriding is a way to apply it in Perl.
+
+Method overriding in simple words appears when we have a class with a method that already exist in a parent class.
+
+Example:
+
+```
+package A;
+
+sub new { return bless {}, shift; };
+sub printMethod { print "A\n"; };
+
+package B;
+
+use parent -norequire, 'A';
+
+sub new { return bless {}, shift; };
+sub printMethod { print "B\n"; };
+
+my $a = A->new();
+my $b = B->new();
+
+A->new()->printMethod();
+B->new()->printMethod();
+
+# Output:
+# A
+# B
+```
+
+
+
+
+How can you call a method of an inherited class?
+
+```
+# Class `A` with `printA` method.
+package A;
+
+sub new { return bless {}, shift; };
+sub printA { print "A"; };
+
+# Class `B` that extends or use the parent class `A`.
+package B;
+
+use parent -norequire, 'A';
+
+sub new { return bless {}, shift; };
+
+# Instance class `B` allows call the inherated method
+my $b = B->new();
+$b->printA();
+```
+
+
+### Perl OS
+
+
+What is Perl Open3?
+
+
+### Perl Packages & Modules
+
+
+What is a Perl package? And a module?
+
+
+
+What is the difference between .pl and .pm extensions?
+
+
+
+What is cpan? And cpanm?
+
+
+
+How can you install a Perl module?
+
\ No newline at end of file