Comment by paulddraper

People quote both too often and too little.

GENERAL RULE

1. Double-quote dollar sign expressions, and nothing else.

  foo

  "$bar"/foo

  baz:"$(cat example.txt)"

  exec cmd "$@"

2. Single-quote words with a literal special character, and nothing else.

  'Die Hard'

  'ke$ha'

---

I should point out that the author's example is NOT fixed by different quoting though.

  # original
  export PATH="$PATH:~/.local/bin/"

  # without unnecessary quotes
  export PATH="$PATH":~/.local/bin/

Because tilde expansion only happens at the beginning of the word.