Re: [Help-bash] Escaping in backquote string in double quoted strings -- query about bash intent

[Greg Wooledge]

On Tue, May 07, 2019 at 08:52:02PM +0800, KHMan wrote:
> If this is inappropriate for help-bash, I can repost it on the dev list. But
> here I am only trying to understand the _intention_ of the code so that I
> can code the appropriate highlighting fix -- it's really still a glorified
> shell user's query.

You might be better off looking at the POSIX spec that bash is trying to
implement, rather than the implementation.

http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_03

  Within the backquoted style of command substitution, <backslash> shall retain
  its literal meaning, except when followed by: '$', '`', or <backslash>. The
  search for the matching backquote shall be satisfied by the first unquoted
  non-escaped backquote; during this search, if a non-escaped backquote is
  encountered within a shell comment, a here-document, an embedded command
  substitution of the $(command) form, or a quoted string, undefined results
  occur. A single-quoted or double-quoted string that begins, but does not end,
  within the "`...`" sequence produces undefined results.

  With the $(command) form, all characters following the open parenthesis to
  the matching closing parenthesis constitute the command. Any valid shell
  script can be used for command, except a script consisting solely of
  redirections which produces unspecified results.

Good luck trying to decipher that.