Prefixing a double-quoted string with a dollar sign (‘$’), such
as $"hello, world",
causes the string to be translated according to the current locale.
The gettext infrastructure performs the lookup and
translation, using the LC_MESSAGES, TEXTDOMAINDIR,
and TEXTDOMAIN shell variables, as explained below.
See the gettext documentation for additional details not covered here.
If the current locale is C or POSIX,
if there are no translations available,
or if the string is not translated, the dollar sign is ignored,
and the string is treated as double-quoted as described above.
Since this is a form of double quoting, the string remains double-quoted
by default, whether or not it is translated and replaced.
If the noexpand_translation option is enabled
using the shopt builtin (see The Shopt Builtin),
translated strings are single-quoted instead of double-quoted.
The rest of this section is a brief overview of how you use gettext to create translations for strings in a shell script named scriptname. There are more details in the gettext documentation.