Understanding Perl Input Record Separators ($/)

Separator Value	Mode	Description
$/ = undef;	Slurp mode	Reads the entire file into a single string all at once.
$/ = ""; (empty string)	Paragraph mode	Reads text block-by-block, delimited by two or more newlines.
$/ = "\n"; (default)	Line-by-line mode	Reads one standard line at a time.
$/ = " "; (space)	Space-delimited mode	Reads characters up to the next space (sometimes referred to as "almost word-by-word").
$/ = "\0";	Null-terminated mode	Reads up to a null character. Extremely useful for processing output from system commands like find -print0.
$/ = \32768; (scalar ref)	Fixed-length mode	Passing a reference to an integer (e.g., \1024) reads exactly that many bytes at a time. Great for fixed-width data or binary files.