29.1.1 Event Designators
An event designator is a reference to a command line entry in the
history list.
!- Start a history substitution, except when followed by a space, tab,
the end of the line, or ‘=’.
!n- Refer to command line n.
!-n- Refer to the command n lines back.
!!- Refer to the previous command. This is a synonym for ‘!-1’.
!string- Refer to the most recent command starting with string.
!?string[?]- Refer to the most recent command containing string. The trailing
‘?’ may be omitted if the string is followed immediately by
a newline.
^string1^string2^- Quick Substitution. Repeat the last command, replacing string1
with string2. Equivalent to
!!:s/string1/string2/.
!#- The entire command line typed so far.