Warn when echo'ing: accidental globbing with "?", history expansion with "!!"

[thp-hatch]

For new checks and feature suggestions

• 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

echo File checksum mismatch! Input changed?

#!/bin/bash

echo Something did not work!!

Here's what shellcheck currently says:

No issues detected!

Here's what I wanted or expected to see:

Warn the user that if a file that matches the "changed?" glob expression (e.g. changedd or changed1) exists, the output message will change. To prevent that, quote the string.

Example error case:

$ touch changedd
$ echo File checksum mismatch! Input changed?
File checksum mismatch! Input changedd

$ ls
...
$ echo foo!!
fools

Proposed fix suggestion:

Surround with double quotes.

echo "File checksum mismatch! Input changed?"

echo "foo!!"

Or alternatively:

echo File checksum mismatch! Input "changed?"