# Environment

Source: https://libtmux.org/en/java/latest/topics/environment/

> Locate tmux objects from process variables and manage the environment inherited by new panes.

tmux exposes two environment APIs. Process variables such as `TMUX` and
`TMUX_PANE` let code inside a pane identify its server and pane. The server also
stores variables through [`set-environment`](https://libtmux.org/en/tmux/latest/manual/set-environment/) and [`show-environment`](https://libtmux.org/en/tmux/latest/manual/show-environment/) for new
processes to inherit. Like the tables in [Options and
hooks](https://libtmux.org/en/java/latest/topics/options-and-hooks/), this persistent store has explicit scopes.

## Locating yourself from inside a pane

Inside a pane, `TMUX` contains `<socket path>,<server pid>,<session id>`, and
`TMUX_PANE` contains the pane ID, such as `%1`. Use these variables to locate
the current tmux objects. Select the object your operation needs:

**Server:** Not listed.

**Session:** Not listed.

**Window:** Not listed.

**Pane:** See the Java context example below.

### Examples

Environment lookup requires valid tmux targeting variables. If your process
can run outside tmux, handle that case before using the result.

### Resolve context identifiers

[`TmuxEnvironment`](<https://libtmux.org/en/java/latest/reference/io-github-libtmux-tmuxenvironment-tmuxenvironment/>) parses `TMUX` and `TMUX_PANE` into identifiers: socket path, server
  PID, [`SessionId`](<https://libtmux.org/en/java/latest/reference/io-github-libtmux-sessionid-sessionid/>), and `Optional<PaneId>`. It returns context data rather than
  a live pane handle:

```java
TmuxEnvironment here = TmuxEnvironment.current().orElseThrow();

try (Server server = Server.open(here.config())) {
    Session mine = server.sessions().stream()
          .filter(session -> session.id().equals(here.session()))
          .findFirst()
          .orElseThrow();
}
```

## tmux's own environment variable store

Like [Options and hooks](https://libtmux.org/en/java/latest/topics/options-and-hooks/),
tmux's persistent environment store has global and per-session scopes. It is
read with [`show-environment`](https://libtmux.org/en/tmux/latest/manual/show-environment/) and updated with [`set-environment`](https://libtmux.org/en/tmux/latest/manual/set-environment/). Newly spawned
processes inherit it; existing processes retain their own environments.

**Set:** Not documented here; see the process-environment note below.

**Read all:** Not documented here; see the process-environment note below.

**Unset:** Not documented here; see the process-environment note below.

[`set-environment`](https://libtmux.org/en/tmux/latest/manual/set-environment/) writes a value. Its `-u` flag removes the entry, while `-r`
marks the variable for exclusion from new processes, including values tmux
inherited at startup. The listing retains an excluded variable as `-NAME`.

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### Process environment

[`SessionSpec.Builder.environment(Map)`](<https://libtmux.org/en/java/latest/reference/io-github-libtmux-sessionspec-sessionspec-builder-environment/>), [`WindowSpec.Builder.environment(Map)`](<https://libtmux.org/en/java/latest/reference/io-github-libtmux-windowspec-windowspec-builder-environment/>),
and [`SplitSpec.Builder.environment(Map)`](<https://libtmux.org/en/java/latest/reference/io-github-libtmux-splitspec-splitspec-builder-environment/>) pass initial variables to
[`new-session -e`](https://libtmux.org/en/tmux/latest/manual/new-session/), [`new-window -e`](https://libtmux.org/en/tmux/latest/manual/new-window/), and [`split-window -e`](https://libtmux.org/en/tmux/latest/manual/split-window/). These creation options
do not change the stored environment of an existing session.