What is $, (dollar comma)?

Question

I see it's used in safe_join https://apidock.com/rails/v5.2.3/ActionView/Helpers/OutputSafetyHelper/safe_join

in irb it returns nil

irb(main):001:0> $,
=> nil

I don't have the answer but `$11123` and `$abc` are also nil. — nlta, Jan 16 '22 at 20:34
https://stackoverflow.com/questions/1896876/what-does-the-character-mean-in-ruby — nlta, Jan 16 '22 at 20:35
I know $ is for global variables, but it seems to be special one — Dorian, Jan 16 '22 at 20:37
@nita: Well, `$11123` is the 11123rd positional parameter of your script. — user1934428, Jan 17 '22 at 08:53

steenslag · Accepted Answer · 2022-01-16T20:44:02.960

3

$, is the separarator output between the arguments to print and the default separarator for Array.join. It is nil by default. Globals

edited Jan 16 '22 at 20:44

answered Jan 16 '22 at 20:42

steenslag

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Thanks, should have looked at `Array#join`, https://apidock.com/ruby/Array/join – Dorian Jan 16 '22 at 20:44
Note that it is also by `print`. Example: `$,='x'; print 5,6;` – user1934428 Jan 17 '22 at 08:55

score 3 · Answer 2 · answered Jan 16 '22 at 20:47

Thankfully, the magic global variables are now properly documented. According to this documentation, $, is

The output field separator for Kernel#print and Array#join.

That means the value of $, is the value that is used by Kernel#print and by Array#join as the default value for joining multiple elements. The default value of $, at startup is nil, which means that there is no separator between elements.

What is $, (dollar comma)?

2 Answers2