Bash/Word-Designators

9.3.2 Word Designators

Word designators are used to select desired words from the event. A ‘:’ separates the event specification from the word designator. It may be omitted if the word designator begins with a ‘^’, ‘$’, ‘*’, ‘-’, or ‘%’. Words are numbered from the beginning of the line, with the first word being denoted by 0 (zero). Words are inserted into the current line separated by single spaces.

For example,

!!: designates the preceding command. When you type this, the preceding command is repeated in toto.
!!:$: designates the last argument of the preceding command. This may be shortened to !$.
!fi:2: designates the second argument of the most recent command starting with the letters fi.

Here are the word designators:

0 (zero): The 0th word. For many applications, this is the command word.
n: The nth word.
^: The first argument; that is, word 1.
$: The last argument.
%: The word matched by the most recent ‘?string?’ search.
x-y: A range of words; ‘-y’ abbreviates ‘0-y’.
*: All of the words, except the 0th. This is a synonym for ‘1-$’. It is not an error to use ‘*’ if there is just one word in the event; the empty string is returned in that case.
x*: Abbreviates ‘x-$’
x-: Abbreviates ‘x-$’ like ‘x*’, but omits the last word.

If a word designator is supplied without an event specification, the previous command is used as the event.