Ubuntu Manpage: kitten-@-set-background-opacity

Name

       kitten-@-set-background-opacity - Set the background opacity

Usage

       kitten @ set-background-opacity  OPACITY

Description

       Set  the  background  opacity  for  the  specified  windows.  This  will  only work if you have turned on
       dynamic_background_opacity in kitty.conf. The background opacity affects all kitty windows in a single OS
       window. For example::

           kitten @ set-background-opacity 0.5

Options

--all, -a [=no]
By default, background opacity are only changed for the currently active OS window. This option
will cause background opacity to be changed in all windows.

--toggle [=no]
When specified, the background opacity for the matching OS windows will be reset to default if it
is currently equal to the specified value, otherwise it will be set to the specified value.

--match, -m
The window to match. Match specifications are of the form: field:query. Where field can be one of:
id, title, pid, cwd, cmdline, num, env, var, state, neighbor, session and recent. query is the
expression to match. Expressions can be either a number or a regular expression, and can be
combined using Boolean operators.

The special value all matches all windows.

For numeric fields: id, pid, num and recent, the expression is interpreted as a number, not a
regular expression. Negative values for id match from the highest id number down, in particular,
-1 is the most recently created window.

The field num refers to the window position in the current tab, starting from zero and counting
clockwise (this is the same as the order in which the windows are reported by the kitten @ ls
command).

The window id of the current window is available as the KITTY_WINDOW_ID environment variable.

The field recent refers to recently active windows in the currently active tab, with zero being
the currently active window, one being the previously active window and so on.

The field neighbor refers to a neighbor of the active window in the specified direction, which can
be: left, right, top or bottom.

The field session matches windows that were created in the specified session. Use the expression
^$ to match windows that were not created in a session and . to match the currently active session
and ~ to match either the currently active sesison or the last active session when no session is
active.

When using the env field to match on environment variables, you can specify only the environment
variable name or a name and value, for example, env:MY_ENV_VAR=2.

Similarly, the var field matches on user variables set on the window. You can specify name or name
and value as with the env field.

The field state matches on the state of the window. Supported states are: active, focused,
needs_attention, parent_active, parent_focused, focused_os_window, self, overlay_parent. Active
windows are the windows that are active in their parent tab. There is only one focused window and
it is the window to which keyboard events are delivered. If no window is focused, the last focused
window is matched. The value focused_os_window matches all windows in the currently focused OS
window. The value self matches the window in which the remote control command is run. The value
overlay_parent matches the window that is under the self window, when the self window is an
overlay.

Note that you can use the kitten @ ls command to get a list of windows.

--match-tab, -t
The tab to match. Match specifications are of the form: field:query. Where field can be one of:
id, index, title, window_id, window_title, pid, cwd, cmdline env, var, state, session and recent.
query is the expression to match. Expressions can be either a number or a regular expression, and
can be combined using Boolean operators.

The special value all matches all tabs.

For numeric fields: id, index, window_id, pid and recent, the expression is interpreted as a
number, not a regular expression. Negative values for id/window_id match from the highest id
number down, in particular, -1 is the most recently created tab/window.

When using title or id, first a matching tab is looked for, and if not found a matching window is
looked for, and the tab for that window is used.

You can also use window_id and window_title to match the tab that contains the window with the
specified id or title.

The index number is used to match the nth tab in the currently active OS window. The recent number
matches recently active tabs in the currently active OS window, with zero being the currently
active tab, one the previously active tab and so on.

The field session matches tabs that were created in the specified session. Use the expression ^$
to match windows that were not created in a session and . to match the currently active session
and ~ to match either the currently active sesison or the last active session when no session is
active.

When using the env field to match on environment variables, you can specify only the environment
variable name or a name and value, for example, env:MY_ENV_VAR=2. Tabs containing any window with
the specified environment variables are matched. Similarly, var matches tabs containing any window
with the specified user variable.

The field state matches on the state of the tab. Supported states are: active, focused,
needs_attention, parent_active, parent_focused and focused_os_window. Active tabs are the tabs
that are active in their parent OS window. There is only one focused tab and it is the tab to
which keyboard events are delivered. If no tab is focused, the last focused tab is matched. The
value focused_os_window matches all tabs in the currently focused OS window.

Note that you can use the kitten @ ls command to get a list of tabs.

--help, -h [=no]
Show help for this command

Global options

--to An address for the kitty instance to control. Corresponds to the address given to the kitty
instance via the --listen-on option or the listen_on setting in kitty.conf. If not specified, the
environment variable KITTY_LISTEN_ON is checked. If that is also not found, messages are sent to
the controlling terminal for this process, i.e. they will only work if this process is run within
a kitty window.

--password
A password to use when contacting kitty. This will cause kitty to ask the user for permission to
perform the specified action, unless the password has been accepted before or is pre-configured in
kitty.conf. To use a blank password specify --use-password as always.

--password-file [=rc-pass]
A file from which to read the password. Trailing whitespace is ignored. Relative paths are
resolved from the kitty configuration directory. Use - to read from STDIN. Use fd:num to read from
the file descriptor num. Used if no --password is supplied. Defaults to checking for the rc-pass
file in the kitty configuration directory.

--password-env [=KITTY_RC_PASSWORD]
The name of an environment variable to read the password from. Used if no --password-file is
supplied. Defaults to checking the environment variable KITTY_RC_PASSWORD.

--use-password [=if-available]
If no password is available, kitty will usually just send the remote control command without a
password. This option can be used to force it to always or never use the supplied password. If set
to always and no password is provided, the blank password is used.

Choices: if-available, always, never

0.44.0 Nov 26, 2025 kitten-@-set-background-opacity(1)