A double-quoted string preceded by a dollar sign (‘$’) will cause
the string to be translated according to the current locale.
If the current locale is
POSIX, the dollar sign
If the string is translated and replaced, the replacement is
Some systems use the message catalog selected by the LC_MESSAGES shell variable. Others create the name of the message catalog from the value of the TEXTDOMAIN shell variable, possibly adding a suffix of ‘.mo’. If you use the TEXTDOMAIN variable, you may need to set the TEXTDOMAINDIR variable to the location of the message catalog files. Still others use both variables in this fashion: TEXTDOMAINDIR/LC_MESSAGES/LC_MESSAGES/TEXTDOMAIN.mo.