Difference between ARGF, $stdin, $*, and $<

[Donkey Agony]

Apologies for such a noob question, but what are the differences
betweeen ARGF, $stdin, $*, and $<?

Thanks!

 

[Malte Milatz]

Donkey Agony:

Apologies for such a noob question, but what are the differences betweeen
ARGF, $stdin, $*, and $<?

STDIN or $stdin is the so-called standard input.

ARGF or $< gives you the content of the files specified on the command line
or, if there aren't any, of standard input.

ARGV or $* gives you the command line arguments as strings.

As an example, take this invocation of a Ruby script (on a Unix-like
system - I don't know whether `echo` is available on Windows systems):
echo "Hi." | ruby test.rb testfile

ARGV will be [ "testfile" ].
$stdin.read will give you "Hi.\n".
ARGF.read will give you the contents of testfile.

Other people may give you more detailed information...

Malte