# libtmux.core/new-window!

- **Module:** libtmux.core
- **Package:** io.github.libtmux:libtmux-clojure
- **Language:** Clojure
- **Kind:** function
- **Source:** https://github.com/libtmux/libtmux-java/blob/5f88402151ff08fc0390dd438b90963692ec3fe4/libtmux-clojure/src/main/clojure/libtmux/core.clj#L254
- **Public owner:** libtmux.core
- **Page:** https://libtmux.org/en/clojure/latest/reference/libtmux-core-new-window/

```
(new-window! session options)
```

Creates a window and returns a fresh captured window occurrence.

Takes a Session ref and `:name`, `:command` (argv), `:directory`, `:environment`,
`:index` (nonnegative integer), and `:detached?` options.
Use [[split-pane!]] to add panes within the new window.

## Examples

Create a detached window and refresh its parent. Use JDK 25 or newer, the Clojure CLI, Git and tmux on Linux or macOS, with /bin/cat and /bin/sh available. These packages are unpublished. In an empty directory, install this exact source into the consumer's isolated Maven repository:

```console
$ git clone https://github.com/libtmux/libtmux-java libtmux-source && \
  git -C libtmux-source checkout --detach 5f88402151ff08fc0390dd438b90963692ec3fe4 && \
  (cd libtmux-source && ./gradlew \
    :libtmux:publishToMavenLocal \
    :libtmux-clojure:publishToMavenLocal \
    --console=plain \
    "-Dmaven.repo.local=$PWD/../m2")
```

Save this file as `deps.edn`. Dependencies resolve from the isolated m2 directory; the core.async dependency is only enabled by its alias.

[Source example](https://github.com/libtmux/libtmux-java/blob/5f88402151ff08fc0390dd438b90963692ec3fe4/examples/api/clojure/deps.edn).

```clojure
{:paths ["src/main/clojure"]
 :mvn/local-repo "m2"
 :deps {org.clojure/clojure {:mvn/version "1.12.6"}
        io.github.libtmux/libtmux-clojure {:mvn/version "0.1.2-SNAPSHOT"}}
 :aliases
 {:core-async
  {:extra-deps
   {io.github.libtmux/libtmux-clojure-core-async {:mvn/version "0.1.2-SNAPSHOT"}}}}}
```

Save this file as `run.sh`. The launcher creates and stops a private server, including after program failure, and reports leaked servers as errors.

[Source example](https://github.com/libtmux/libtmux-java/blob/5f88402151ff08fc0390dd438b90963692ec3fe4/examples/api/run.sh).

```sh
#!/bin/sh
set -eu

if [ "$#" -eq 0 ]; then
    printf 'Usage: sh run.sh program [arguments...]\n' >&2
    exit 2
fi
binary=$(command -v "${TMUX_BIN:-tmux}")
root=${API_RUN_ROOT:-/tmp/libtmux-java-dev}

# A client that names no socket follows TMUX or LIBTMUX_SOCKET*, and otherwise lands on the default
# socket under TMUX_TMPDIR. The program gets none of them, and a TMUX_TMPDIR of its own below.
unset TMUX TMUX_PANE
for name in $(env | sed -n 's/^\(LIBTMUX_SOCKET[A-Za-z0-9_]*\)=.*/\1/p'); do
    unset "$name"
done

mkdir -p "$root"
directory=$(mktemp -d "$root/api.XXXXXX")
tmpdir=$(mktemp -d "$root/tmpdir.XXXXXX")
socket="$directory/tmux.sock"
config="$directory/tmux.conf"

serves() {
    "$binary" -S "$1" display-message -p '#{pid}' >/dev/null 2>&1
}

# Stops the server on the socket, then waits for it to stop answering.
stop() {
    "$binary" -S "$1" kill-server || return 1
    attempts=0
    while serves "$1" && [ "$attempts" -lt 60 ]; do
        sleep 0.05
        attempts=$((attempts + 1))
    done
    ! serves "$1"
}

cleanup() {
    status=$?
    trap - 0 HUP INT TERM PIPE
    # A closed output must not end the cleanup, whose messages are the only thing left to write.
    trap '' PIPE
    set +e
    stuck=
    left=
    if [ -S "$socket" ] && serves "$socket" && ! stop "$socket"; then
        stuck="$stuck tmux.sock"
    fi
    # Every socket anywhere under either directory, without following links. Only one a server answers
    # on is a leak; the runner's own is expected to be there.
    old_ifs=$IFS
    IFS='
'
    set -f
    for candidate in $(find "$tmpdir" "$directory" -type s 2>/dev/null); do
        [ "$candidate" = "$socket" ] && continue
        serves "$candidate" || continue
        case "$candidate" in
            "$tmpdir"/*) name=${candidate#"$tmpdir"/} ;;
            *) name=${candidate#"$directory"/} ;;
        esac
        left="$left $name"
        stop "$candidate" || stuck="$stuck $name"
    done
    set +f
    IFS=$old_ifs
    if [ -n "$stuck" ]; then
        printf 'tmux still answers on%s after kill-server; kept %s and %s under the runner root\n' \
            "$stuck" "${directory##*/}" "${tmpdir##*/}" >&2
        exit 1
    fi
    rm -rf "$directory" "$tmpdir" || exit 1
    if [ -n "$left" ]; then
        printf 'The program left a tmux server running:%s\n' "$left" >&2
        exit 1
    fi
    exit "$status"
}
trap cleanup 0
trap 'exit 1' HUP INT TERM PIPE

# A default socket path longer than this does not fit in sun_path.
default_socket="$tmpdir/tmux-$(id -u)/default"
if [ "$(printf '%s' "$default_socket" | wc -c)" -gt 100 ]; then
    printf 'API_RUN_ROOT is too long for a tmux socket\n' >&2
    exit 1
fi
TMUX_TMPDIR=$tmpdir
export TMUX_TMPDIR

printf 'set-option -g default-shell /bin/sh\n' > "$config"
"$binary" -S "$socket" -f "$config" new-session -d -s work-one -n editor /bin/cat
"$binary" -S "$socket" split-window -h -t '=work-one:editor' /bin/cat
"$binary" -S "$socket" new-window -d -t '=work-one' -n logs /bin/cat
"$binary" -S "$socket" new-session -d -s work-two -n editor /bin/cat
"$@" "$binary" "$socket" "$config"
"$binary" -S "$socket" has-session -t '=work-one'
"$binary" -S "$socket" has-session -t '=work-two'
```

Save the complete program as `src/main/clojure/libtmux/examples/api/new_window.clj`, creating its parent directories. Closing its client leaves the launcher's server running.

[Source example](https://github.com/libtmux/libtmux-java/blob/5f88402151ff08fc0390dd438b90963692ec3fe4/examples/src/main/clojure/libtmux/examples/api/new_window.clj).

```clojure
(ns libtmux.examples.api.new-window
  "Create a detached window, then refresh its parent session."
  (:require [clojure.string :as str]
            [libtmux.core :as tm]
            [libtmux.data :as data]))

(defn -main [& args]
  (when-not (= 3 (count args))
    (throw (IllegalArgumentException. "expected: tmux-binary socket-path config-file")))
  (let [[binary socket config] args]
    (with-open [server (tm/open! {:binary binary :socket-path socket
                                 :config-file config})]
      (let [before (data/exactly-one
                    (filter #(= "work-one" (:session/name %)) (tm/sessions! server)))
            window (tm/new-window! (:tmux/ref before)
                                   {:name "api-window" :command ["/bin/cat"]
                                    :detached? true})
            after (tm/refresh! (:tmux/ref before))]
        (assert (= 2 (count (data/windows before))))
        (assert (= 3 (count (data/windows after))))
        (println (str "created=" (:window/name window)))
        (println (str "windows="
                      (str/join "," (sort (map :window/name (data/windows after))))))))))
```

Run it with the private fixture. Set TMUX_BIN to select another tmux binary:

```console
$ sh run.sh clojure \
  -J-Dclojure.main.report=stderr \
  -M \
  -m libtmux.examples.api.new-window
```

Expected output:

```text
created=api-window
windows=api-window,editor,logs
```

## Parameters

- `session`
- `options`

## tmux command

The tmux commands behind `new-window!`.

- [`new-window`](/en/tmux/latest/manual/new-window/)

## tmux C API

The C declarations in tmux that implement these commands.

- [`cmd_new_window_entry`](/en/tmux/latest/reference/c-variable-cmd_new_window_entry/) (attribute)
- [`cmd_new_window_exec`](/en/tmux/latest/reference/c-function-cmd-new-window-c-cmd_new_window_exec/) (function)

## In other ports

Create a window

| Language | Equivalent |
| --- | --- |
| Python | [`libtmux.Session.new_window`](/en/py/latest/reference/libtmux-session-new_window/) (method) |
| Ruby | [`LibTmux::Session#new_window`](/en/ruby/latest/reference/libtmux-session-new_window/) (method) |
| Lua | [`libtmux.Session:new_window`](/en/lua/latest/reference/libtmux-session-new_window/) (method) |
| Erlang | [`tmux_window:create/2`](/en/erlang/latest/reference/tmux_window-create-2/) (function) |
| Haskell | No public Haskell equivalent is implemented; the current modules expose scalar values and version parsing. |
| TypeScript | [`session.Session.newWindow`](/en/ts/latest/reference/session-session-newwindow/) (method) |
| Rust | [`session.Session.new_window`](/en/rs/latest/reference/session-session-new_window/) (method) |
| Go | [`tmux.Session.NewWindow`](/en/go/latest/reference/tmux-session-newwindow/) (method) |
| Java | [`io.github.libtmux.Session.newWindow`](/en/java/latest/reference/io-github-libtmux-session-session-newwindow/) (method) |
| Kotlin | [`io.github.libtmux.kotlin.Session.newWindow`](/en/kotlin/latest/reference/io-github-libtmux-kotlin-session-newwindow/) (method) |
| Scala | [`io.github.libtmux.scaladsl.Session.newWindow`](/en/scala/latest/reference/io-github-libtmux-scaladsl-session-newwindow/) (method) |
| C# | [`LibTmux.Session.CreateWindowAsync`](/en/csharp/latest/reference/libtmux-session-createwindowasync/) (method) |
| C++ | [`libtmux::Session::new_window`](/en/cxx/latest/reference/libtmux-session-new_window/) (method) |
| Swift | [`Server.newWindow(in:named:startDirectory:at:environment:shell:)`](/en/swift/latest/reference/server-newwindow(in-named-startdirectory-)/) (method) |
| OCaml | [`Libtmux_unix.Client.create_window`](/en/ocaml/latest/reference/libtmux_unix-client-create_window/) (function) |
| Perl | [`LibTmux::Server::new_window`](/en/perl/latest/reference/libtmux-server-new_window/) (method). Explicit Server operation. Captured entities remain local observations; use a new snapshot to observe changes. |

No equivalent is recorded in PowerShell, Julia, Elixir, Common Lisp or F#.