To answer some of your numbered questions

1. see Cwd

2. File::Find::Rule has found favor and can provide a good solution to finding files in the specified directories. Super Search is a good source for finding out more about File::Find::Rule as well as any other questions you might have.

To find the largest .txt file in each directory, you might want to see reduce from List::Util.
Update The largest could be found this way as well. 

my @files = glob "*.txt";

my $largest = shift @files;

for my $file (@files) {
    $largest = $file if -s $file > -s $largest;
}

[download]

3. see mkdir

please help with directing me to which functions to use, particularly for sorting files by size and obtaining a list of the largest file in each subdirectory as a string separated by spaces,

Because some filenames/directories can themselves have spaces, it might be better to separate them with a tab character or even separate them by the newline character.

To see how to create a new file, look at the documentation for open.

In reply to Re: Advice/help with beginner script (file sorting, execute command line command) by Cristoforo
in thread Advice/help with beginner script (file sorting, execute command line command) by UserMane

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