linux - Bash echo with an $ character outside the string

Question

Can anyone explain what is the difference between

echo $"Starting $CMD" 

and

echo "String $CMD"

They seem to look the same.

Answer 1

Look up the QUOTING section of the bash man page:

Words of the form $'string' are treated specially. The word expands to string, with backslash- escaped characters replaced as specified by the ANSI C standard. Backslash escape sequences, if present, are decoded as follows:

• a alert (bell)
• backspace
• e an escape character
• f form feed
• new line
• carriage return
• horizontal tab
• v vertical tab
• backslash
• ' single quote
• nn the eight-bit character whose value is the octal value nnn (one to three digits)
• xHH the eight-bit character whose value is the hexadecimal value HH (one or two hex digits)
• cx a control-x character

The expanded result is single-quoted, as if the dollar sign had not been present.

And note the follow description double quoted strings preceded by $ ($"string"):

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 C or POSIX, the dollar sign is ignored. If the string is translated and replaced, the replacement is double-quoted.