Add quotes around variables in adduser.sh and replace backticks with $()

[bcr]

Summary

This patch does the following:

• Replaces backticks with $()
• add double quotes around variables to prevent word splitting and globbing

Test Plan

Run through the adduser.sh to see if a user gets created like before

[delphij]

Most of the $()'s should be quoted too, since you are already there, maybe get the script through shellcheck?

(And for variables, it's a good idea to use ${var} instead of $var.

usr.sbin/adduser/adduser.sh

291

shouldn't this be quoted too?

[bcr]

In D40747#927028, @delphij wrote:

Most of the $()'s should be quoted too, since you are already there, maybe get the script through shellcheck?

That's what I did, trying to keep the diffs small enough by not doing too much at once.

(And for variables, it's a good idea to use ${var} instead of $var.

I can do that, will update the diff to include this and the comment above. Thanks.

[bcr]

Address comments:

• turn $vars into ${var}
• quote them and the $()