Exit in Perl

Here’s an idiomatic Perl example that demonstrates the concept of exiting a program with a specific status code:

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

# This subroutine will not be executed due to the early exit
sub cleanup {
    print "Cleaning up...\n";
}

# Register the cleanup subroutine to run when the script exits normally
END {
    cleanup();
}

print "Starting the program...\n";

# Exit with status 3
exit 3;

# This line will never be reached
print "This won't be printed.\n";

This Perl script demonstrates how to exit a program with a specific status code using the exit function. Here’s a breakdown of the code:

1. We start with the shebang line and enable strict mode and warnings for better code quality.

2. We define a cleanup subroutine that would normally be used for cleanup operations.

3. We use an END block to register the cleanup subroutine to run when the script exits normally.

4. We print a message to indicate the start of the program.

5. We use the exit 3 statement to immediately terminate the program with an exit status of 3.

6. The last print statement will never be executed due to the early exit.

To run this script:

1. Save the code in a file named exit_example.pl.
2. Make the script executable: chmod +x exit_example.pl
3. Run the script: ./exit_example.pl

To check the exit status after running the script:

$ ./exit_example.pl
Starting the program...
$ echo $?
3

Note that the cleanup subroutine is not called when using exit. This is similar to the behavior of os.Exit in the original example.

In Perl, you can also use the die function to exit with a non-zero status and print an error message:

die "Error occurred!\n";

This will exit with status 255 by default, but you can set a specific exit code using the $! special variable:

$! = 3;
die "Error occurred!\n";

Using exit or die in Perl allows you to terminate the program immediately with a specific exit status, which can be useful for error handling and script automation.