[Perl] Get Size of Files or Directories

Sample code:

use File::Find;

# Get size of entry (file or directory) in bytes.
sub entry_size {
    if (-f $_[0]) {
        -s $_[0];
    } elsif (-d $_[0]) {
        my $size = 0;
        finddepth( sub { $size += -s if -f $_ }, $_[0] );
        $size;
    }
}

Notes:

1. File::Find module - Traverse a directory tree. Usage:
   

   finddepth(\&wanted, @directories);
   finddepth(\%options, @directories);

2. File tests and their meanings
   

   File test	Meaning
   -r	File or directory is readable by this (effective) user or group
   -w	File or directory is writable by this (effective) user or group
   -x	File or directory is executable by this (effective) user or group
   -o	File or directory is owned by this (effective) user
   -R	File or directory is readable by this real user or group
   -W	File or directory is writable by this real user or group
   -X	File or directory is executable by this real user or group
   -O	File or directory is owned by this real user
   -e	File or directory name exists
   -z	File exists and has zero size (always false for directories)
   -s	File or directory exists and has nonzero size (the value is the size in bytes)
   -f	Entry is a plain file
   -d	Entry is a directory
   -l	Entry is a symbolic link
   -S	Entry is a socket
   -p	Entry is a named pipe (a “fifo”)
   -b	Entry is a block-special file (like a mountable disk)
   -c	Entry is a character-special file (like an I/O device)
   -u	File or directory is setuid
   -g	File or directory is setgid
   -k	File or directory has the sticky bit set
   -t	The filehandle is a TTY (as reported by the isatty() system function; filenames can’t be tested by this test)
   -T	File looks like a “text” file
   -B	File looks like a “binary” file
   -M	Modification age (measured in days)
   -A	Access age (measured in days)
   -C	Inode-modification age (measured in days)

   
   
3. @_ is the list of parameters to a sub. So if you write a sub, you refer to the first parameter in it as $_[0], the second parameter as $_[1] and so on. $_ is known as the "default input and pattern matching space."