# libtmux:wait-for

- **Package:** libtmux
- **Language:** Common Lisp
- **Kind:** function
- **Source:** https://github.com/libtmux/libtmux-lisp/blob/c2e5fc4ed3befda21f45dfa5d5868c38fd138311/src/server-operations.lisp#L129
- **Public owner:** libtmux
- **Page:** https://libtmux.org/en/lisp/latest/reference/libtmux-wait-for/

```
(wait-for client channel &key (operation :wait) cancel-token timeout output-limit)
```

Wait, signal, lock or unlock the literal CHANNEL; return a COMMAND-OUTCOME.
OPERATION is :WAIT (default), :SIGNAL, :LOCK or :UNLOCK. CHANNEL is a nonempty
string without NUL. This call performs I/O on an existing daemon. :WAIT and
:LOCK require tmux 3.8, whose client-loss handling removes queued waiters;
older daemons signal UNSUPPORTED-CAPABILITY before dispatch. :SIGNAL and
:UNLOCK support the library's tmux floor.

A signal wakes current waiters or retains one pending wake. Repeated signals
are not an idempotent latch or a counting semaphore. Locks have no owner and
survive this call and CLOSE-CLIENT within the daemon's lifetime; unlock them
explicitly. Continuation does not identify a sender; server shutdown can flush
waiting requests. Signals and locks
share a channel, so applications should use separate names for those protocols.

One operation owns CLIENT at a time. Use another client to signal or unlock
a blocked call. TIMEOUT and OUTPUT-LIMIT cover preflight and waiting together.
Cancellation or lost acknowledgement can leave signal consumption or a lock
grant uncertain; inspect ERROR-OUTCOME. Never retries or unlocks automatically.
Signals INVALID-ARGUMENT, COMMAND-FAILED or an operational condition.

See also: `libtmux:cancel`, `libtmux:close-client`, `libtmux:error-outcome`, `libtmux:outcome-status`, `libtmux:unsupported-capability`.

## Parameters

- `client`
- `channel`
- `operation?`
- `cancel-token?`
- `timeout?`
- `output-limit?`

## tmux command

The tmux commands behind `wait-for`.

- [`wait-for`](/en/tmux/latest/manual/wait-for/)

## tmux C API

The C declarations in tmux that implement these commands.

- [`cmd_wait_for_entry`](/en/tmux/latest/reference/c-variable-cmd_wait_for_entry/) (attribute)
- [`cmd_wait_for_exec`](/en/tmux/latest/reference/c-function-cmd-wait-for-c-cmd_wait_for_exec/) (function)

## Guides

Pages that discuss `wait-for`.

### Examples

- [Capture pane output](/en/lisp/latest/examples/capture-pane-output/)

### Guides

- [Explicit operations](/en/lisp/latest/guides/operations/)
- [REPL tutorial](/en/lisp/latest/guides/tutorial/)