Console input and output in Perl

These snippets demonstrate console input and output in Perl. The first snippet simply asks for input and outputs it back to you and the second snippet interprets commands and displays the results.

Receive user input and print it back

#!/usr/bin/perl

print "Your input: ";

# Receive user input from standard input
my $consoleInput = <STDIN>;

# Output the received input
print "You entered: ".$consoleInput."\n";

Output:

Your input: hello
You entered: hello

Interpret commands and print the results

#!/usr/bin/perl

use Switch;
use POSIX qw(strftime);

# Show the available commands
printHelp();

# Loop continuesly and ask for command input
while(1){
  print "> ";
  chomp($commandInput = <STDIN>);

  switch($commandInput){
    case "help" { printHelp(); }
    case "date" { printDate(); }
    case "exit" { die "Goodbye!"; }
    # Print an error message when the user enters an invalid command
    else { printError(); }
  }
}

# Prints the help message
sub printHelp(){
print "The available commands are:  \n".
	"help - Prints this help message \n".
	"date - Prints the current date and time \n".
	"exit - Quits this script\n";
}

# Displays the current date and time
sub printDate(){
  print strftime('%d-%m-%Y %H:%M:%S', localtime)."\n";
}

# Prints an error message
sub printError(){
  print "Invalid command\n";
}

Output:

The available commands are:
help - Prints this help message
date - Prints the current date and time
exit - Quits this script
> date
20-05-2011 19:53:10
> help
The available commands are:
help - Prints this help message
date - Prints the current date and time
exit - Quits this script
> exit
Goodbye! at command.pl line 17, <STDIN> line 3.