Word Designators (Bash Reference Manual)

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.