SC2216: false positive for piping yes or letter y/n to commands that ask yes/no questions.

[astkaasa]

For bugs

• Rule Id (if any, e.g. SC1000): SC2216
• My shellcheck version (shellcheck --version or "online"):
• The rule's wiki page does not already cover this (e.g. https://shellcheck.net/wiki/SC2086)
• I tried on https://www.shellcheck.net/ and verified that this is still a problem on the latest commit

For new checks and feature suggestions

• https://www.shellcheck.net/ (i.e. the latest commit) currently gives no useful warnings about this
• I searched through https://github.com/koalaman/shellcheck/issues and didn't find anything related

Here's a snippet or screenshot that shows the problem:

#!/bin/bash

yes | cp -r dist/* .

Here's what shellcheck currently says:

$ shellcheck myscript
 
[Line 3:](javascript:setPosition(3, 7))
yes | cp -r dist/* .
      ^-- [SC2216](https://www.shellcheck.net/wiki/SC2216) (warning): Piping to 'cp', a command that doesn't read stdin. Wrong command or missing xargs?

$

Here's what I wanted or expected to see:

Here yes is used to pipe y to commands that ask yes/no questions.

Actually echo any word begin with y/n (case insensitive) should be valid too, but it may be too difficult to be exempted from this rule.