exclamation

Repeat the last command

$ !!

$ ![string]

$ ![N]

$ !-[N]

$ ^[old]^[new]

$ [command] !$

! [event][:word][:modifier]

! (history expansion) allows reusing and modifying previous commands. It's a shell feature (bash, zsh) that expands references to command history before execution.
Common patterns:
- sudo !! - Rerun last command with sudo
- !$ - Last argument of previous command
- !!:s/foo/bar/ - Repeat last command with substitution
- !vim - Run most recent vim command
History expansion happens before other expansions, allowing powerful command reuse with modifications.

!!

The previous command

Command line number n

Current command minus n

Most recent command starting with string

Most recent command containing string

Current command line typed so far

:0

Command name

Nth argument (0-indexed)

First argument

Last argument

All arguments except command

Range of arguments

:h

Remove trailing filename (head/directory)

Remove leading path (tail/filename)

Remove file extension (root)

Remove all but extension

Substitute first occurrence

Substitute all occurrences

Print without executing

History expansion can cause unexpected substitutions in strings containing !. Use single quotes or escape with backslash.
The ! character in double quotes may expand. Use set +H to disable history expansion if problematic.
Not available in all shells or in non-interactive mode.

history(1), fc(1), bash(1), zsh(1)