How do I write an if statement in Perl?

The example of if else-if statement in Perl language is given below.

Table of Contents

print “Enter a Number to check grade\n”;
$num = <>;
if( $num < 0 || $num > 100){
printf “Wrong Number\n”;
}elsif($num >= 0 && $num < 50){
printf “Fail\n”;
}elsif($num >= 0 && $num < 60){
printf “D Grade\n”;

Is there else if in Perl?

The “else if” keyword is spelled elsif in Perl. There’s no elif or else if either. It does parse elseif , but only to warn you about not using it.

What are conditional statements in Perl?

Perl conditional statements helps in the decision making, which require that the programmer specifies one or more conditions to be evaluated or tested by the program, along with a statement or statements to be executed if the condition is determined to be true, and optionally, other statements to be executed if the …

How do you declare a pearl variable in UNIX?

Creating Variables

Perl variables do not have to be explicitly declared to reserve memory space. The declaration happens automatically when you assign a value to a variable. The equal sign (=) is used to assign values to variables.

What is $_ in Perl?

The most commonly used special variable is $_, which contains the default input and pattern-searching string. For example, in the following lines − #!/usr/bin/perl foreach (‘hickory’,’dickory’,’doc’) { print $_; print “\n”; }

What is $@ in Perl?

$@ The Perl syntax error or routine error message from the last eval, do-FILE, or require command. If set, either the compilation failed, or the die function was executed within the code of the eval.

What is =~ in Perl?

The Binding Operator, =~
Matching against $_ is merely the default; the binding operator ( =~ ) tells Perl to match the pattern on the right against the string on the left, instead of matching against $_ .

How do I run a UNIX command in Perl script?

How to execute Unix/shell commands in a Perl script?

exec”” syntax: exec “command”;
system() syntax: system( “command” );
Backticks “ or qx// syntax: `command`;
IPC::Open2. syntax: $output = open2(\*CHLD_OUT, \*CHLD_IN, ‘command arg1 arg2’ );
IPC::Open3.

What is $_ called in Perl?

There is a strange scalar variable called $_ in Perl, which is the default variable, or in other words the topic. In Perl, several functions and operators use this variable as a default, in case no parameter is explicitly used. In general, I’d say you should NOT see $_ in real code.

What is $_ in Perl script?

What is Perl in UNIX?

Perl is a script language, which is compiled each time before running. That unix knows that it is a perl script there must be the following header at the topline of every perl script: #!/usr/bin/perl where the path to perl has to be correct and the line must not exeed 32 charachters.

What is my () in Perl?

my keyword in Perl declares the listed variable to be local to the enclosing block in which it is defined. The purpose of my is to define static scoping. This can be used to use the same variable name multiple times but with different values.

How do you call a shell command in a Perl script?

From Perl HowTo, the most common ways to execute external commands from Perl are:

my $files = `ls -la` — captures the output of the command in $files.
system “touch ~/foo” — if you don’t want to capture the command’s output.
exec “vim ~/foo” — if you don’t want to return to the script after executing the command.

What is $$ in Perl?

$$ The process number of the perl running this script. (Mnemonic: same as shells.) $? The status returned by the last pipe close, backtick (\`\`) command or system operator.

How do I run a Perl script in UNIX?

at the top of your perl script, mark the script as executable with the UNIX chmod command, and execute the perl program by simply typing its name at a UNIX prompt.

How do I run a Perl code in Linux?

Write and Run Your First Script. All you need to write Perl programs is a text editor.
Write Your Script. Create a new text file and type the following exactly as shown: #!usr/bin/perl.
Run Your Script. Back at the command prompt, change to the directory where you saved the Perl script.

What does $$ mean in Perl?

The variable $$ is, as you’ve written, PID of current process: print $$ . “\n”; What you’ve written in your script is $$record{$surrogate_name} , which means accessing an element of a hash and is equivalent to $record->{$surrogate_name} . Other from that, $$name usually means dereferencing a reference to a scalar.

What is the difference between -> and => in Perl?

What is the exact difference between :: and -> in Perl? -> sometimes works where :: does not. -> is used for dereferencing; :: is used for referring to other packages.

How do I run a Unix command in Perl?

How do I use grep in Perl?

The grep() function in Perl used to extract any element from the given array which evaluates the true value for the given regular expression.

Syntax: grep(Expression, @Array)
Parameters:
Returns: any element from the given array which evaluates the true value for the given regular expression.

What is $$ in Perl script?

$$ – The process number of the Perl running this script. $0 – Contains the name of the program being executed.

How do I run a perl script in Linux?

There are many ways to run Perl scripts on Linux:

Run the “perl” command with the Perl script included in the command line.
Run the “perl” command with the Perl script supplied from the standard input stream.
Run the “perl” command with the Perl script supplied in a file.
Run Perl script files as commands.

What is perl in Unix?

How do I run a perl script in Unix?

How do I run a .pl script in Unix?

Type ls -l example.pl , and look for an x in the first column (fourth character, in particular). If it’s not there, you need to make the script executable with chmod a+x example.pl . Finally, to run the program, you need to use ./example.pl .

How do I write an if statement in Perl?