The tilde(~) expansion in Mac/Linux has several pathnames.^[1]GNU Bash: Tilde Expansion^[2] The Magic ~: Bash Tilde Expansion with 5 Examples

• It could be ${HOME} if you do not specify the username.
  If you specify the user, it will expend the home directory of the user.
  For example,

  $ echo ~
  /Users/yourusername
  $ echo ~otheruser
  /Users/otheruser

• It contains the working directory by +/-
  For example,

  $ echo ~+
  /Users/current_directory
  $ echo ~-
  /Users/old/previous_directory

In shell, if you want to expand it,

EXPAND_PATH=`eval echo ~otheruse/bin/`