tmux client library for Kotlin

Control tmux, connect to and create servers, navigate sessions, windows, and panes, send keys, watch for changes via control mode, capture pane contents.

Examples

Complete programs, sourced from the code each port tests.

Install

implementation("io.github.libtmux:libtmux-kotlin:0.1.0")

At a glance

Server → Session → Window → Pane. Each level of the tmux hierarchy has its own entry in the Kotlin API, with the tmux object it wraps.

Type	Wraps
`io.github.libtmux.kotlin.Server`	A tmux server
`io.github.libtmux.kotlin.Session`	A session, ID `$n`
`io.github.libtmux.kotlin.Window`	A window in a session, ID `@n`
`io.github.libtmux.kotlin.Pane`	A pane in a window, ID `%n`

What it does

Start with Kotlin

+ Error handling + Cleanup

import io.github.libtmux.ServerConfig
import io.github.libtmux.ServerEndpoint
import io.github.libtmux.TextOutcome
import io.github.libtmux.kotlin.*
import java.nio.file.Path
import java.time.Duration
import java.util.UUID
import kotlinx.coroutines.runBlocking
import kotlin.time.Duration.Companion.seconds

fun main() = runBlocking {
    val socket = "libtmux-home-${UUID.randomUUID()}"
    val config = ServerConfig.builder()
        .endpoint(ServerEndpoint.namedSocket(socket))
        .configFile(Path.of("/dev/null"))
        .defaultTimeout(Duration.ofSeconds(5))
        .build()

    withServer(config) { server ->
        val session = server.newSession("work")
        val pane = session.activeWindow?.activePane
            ?: error("no active pane")

        pane.sendLine("printf '\\nrea%s\\n' dy")
        val outcome = pane.awaitText("ready", timeout = 5.seconds)
        check(outcome != TextOutcome.TIMED_OUT)

        val lines = pane.capture()
        check(lines.any { it.trim() == "ready" })

        val run = pane.run("echo hi && exit 3", timeout = 5.seconds)
        check(run.exitStatus.orNull() == 3)

        println("ready; exit ${run.exitStatus.orNull()}")
    }
}

import io.github.libtmux.ServerConfig
import io.github.libtmux.ServerEndpoint
import io.github.libtmux.TextOutcome
import io.github.libtmux.kotlin.*
import java.nio.file.Path
import java.time.Duration
import java.util.UUID
import kotlinx.coroutines.runBlocking
import kotlin.time.Duration.Companion.seconds

fun main() = runBlocking {
    val socket = "libtmux-home-${UUID.randomUUID()}"
    val config = ServerConfig.builder()
        .endpoint(ServerEndpoint.namedSocket(socket))
        .configFile(Path.of("/dev/null"))
        .defaultTimeout(Duration.ofSeconds(5))
        .build()

    withServer(config) { server ->
        try {
            val session = server.newSession("work")
            val pane = session.activeWindow?.activePane
                ?: error("no active pane")

            pane.sendLine("printf '\\nrea%s\\n' dy")
            val outcome = pane.awaitText("ready", timeout = 5.seconds)
            check(outcome != TextOutcome.TIMED_OUT)

            val lines = pane.capture()
            check(lines.any { it.trim() == "ready" })

            val run = pane.run("echo hi && exit 3", timeout = 5.seconds)
            check(run.exitStatus.orNull() == 3)

            println("ready; exit ${run.exitStatus.orNull()}")
        } catch (error: Exception) {
            throw IllegalStateException(
                "tmux quickstart failed", error
            )
        }
    }
}

import io.github.libtmux.ServerConfig
import io.github.libtmux.ServerEndpoint
import io.github.libtmux.TextOutcome
import io.github.libtmux.kotlin.*
import java.nio.file.Path
import java.time.Duration
import java.util.UUID
import kotlinx.coroutines.NonCancellable
import kotlinx.coroutines.runBlocking
import kotlinx.coroutines.withContext
import kotlin.time.Duration.Companion.seconds

fun main() = runBlocking {
    val socket = "libtmux-home-${UUID.randomUUID()}"
    val config = ServerConfig.builder()
        .endpoint(ServerEndpoint.namedSocket(socket))
        .configFile(Path.of("/dev/null"))
        .defaultTimeout(Duration.ofSeconds(5))
        .build()

    withServer(config) { server ->
        try {
            val session = server.newSession("work")
            val pane = session.activeWindow?.activePane
                ?: error("no active pane")

            pane.sendLine("printf '\\nrea%s\\n' dy")
            val outcome = pane.awaitText("ready", timeout = 5.seconds)
            check(outcome != TextOutcome.TIMED_OUT)

            val lines = pane.capture()
            check(lines.any { it.trim() == "ready" })

            val run = pane.run("echo hi && exit 3", timeout = 5.seconds)
            check(run.exitStatus.orNull() == 3)

            println("ready; exit ${run.exitStatus.orNull()}")
        } finally {
            withContext(NonCancellable) {
                server.killServer()
            }
        }
    }
}

import io.github.libtmux.ServerConfig
import io.github.libtmux.ServerEndpoint
import io.github.libtmux.TextOutcome
import io.github.libtmux.kotlin.*
import java.nio.file.Path
import java.time.Duration
import java.util.UUID
import kotlinx.coroutines.NonCancellable
import kotlinx.coroutines.runBlocking
import kotlinx.coroutines.withContext
import kotlin.time.Duration.Companion.seconds

fun main() = runBlocking {
    val socket = "libtmux-home-${UUID.randomUUID()}"
    val config = ServerConfig.builder()
        .endpoint(ServerEndpoint.namedSocket(socket))
        .configFile(Path.of("/dev/null"))
        .defaultTimeout(Duration.ofSeconds(5))
        .build()

    withServer(config) { server ->
        try {
            val session = server.newSession("work")
            val pane = session.activeWindow?.activePane
                ?: error("no active pane")

            pane.sendLine("printf '\\nrea%s\\n' dy")
            val outcome = pane.awaitText("ready", timeout = 5.seconds)
            check(outcome != TextOutcome.TIMED_OUT)

            val lines = pane.capture()
            check(lines.any { it.trim() == "ready" })

            val run = pane.run("echo hi && exit 3", timeout = 5.seconds)
            check(run.exitStatus.orNull() == 3)

            println("ready; exit ${run.exitStatus.orNull()}")
        } catch (error: Exception) {
            throw IllegalStateException(
                "tmux quickstart failed", error
            )
        } finally {
            withContext(NonCancellable) {
                server.killServer()
            }
        }
    }
}

Run this example

JDK 25 and tmux on Linux/macOS; Gradle resolves Kotlin 2.4.10

Save the program above as src/main/kotlin/Main.kt in a new directory, along with the files below.

Cleanup is omitted; the private tmux server and its temporary files may remain. Select Cleanup to remove them when the program finishes. The program stops its private tmux server and removes any temporary files it created when it finishes. Error handling adds diagnostics; every version checks required results and deadlines.

build.gradle.kts

plugins {
    kotlin("jvm") version "2.4.10"
    application
}

repositories { mavenCentral() }

dependencies {
    implementation("io.github.libtmux:libtmux-kotlin:0.1.0")
}

java { toolchain { languageVersion.set(JavaLanguageVersion.of(25)) } }
kotlin { jvmToolchain(25) }

application { mainClass.set(providers.gradleProperty("exampleMain")) }

settings.gradle.kts

rootProject.name = "api-example"

gradle.properties

org.gradle.jvmargs=-Xmx2g -XX:MaxMetaspaceSize=768m -Dfile.encoding=UTF-8
kotlin.daemon.jvmargs=-Xmx2g
org.gradle.workers.max=2

Setup and run

# Save the files above at their displayed relative paths.
git clone https://github.com/libtmux/libtmux-java.git libtmux-source
git -C libtmux-source checkout --detach 5c181887918351119bfdb3a046719fa792048e59
./libtmux-source/gradlew --project-dir . --console=plain --no-daemon --max-workers=2 \
  installDist -PexampleMain=MainKt
SHELL=/bin/sh build/install/api-example/bin/api-example

Expected output

ready; exit 3

Library revision: 5c1818879183.

Typed API

Typed objects instead of parsed format strings: io.github.libtmux.kotlin.Pane
Addressing by tmux ID: io.github.libtmux.kotlin.Pane.id
Filtering and queries over tmux objects: io.github.libtmux.kotlin.Iterable.filter

What you get over the tmux CLI

Connect to or start a tmux server: io.github.libtmux.kotlin.Server.Companion.open
Traversal from a server down to its panes: io.github.libtmux.kotlin.Server.panes
Send keys to a pane: io.github.libtmux.kotlin.Pane.sendKeys
Watch for changes through tmux control mode: io.github.libtmux.kotlin.ControlClient
Capture pane contents: io.github.libtmux.kotlin.Pane.capture
Arguments passed as a list, with no shell quoting: io.github.libtmux.kotlin.Server.cmd
Async operations: io.github.libtmux.kotlin.Server.panes

Scripting & web

Compiled & native

JVM

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BEAM

tmux

tmux client library for Kotlin

Guides

Examples

API reference

Install

At a glance

What it does

Start with Kotlin

Setup and run

Expected output

Typed API

What you get over the tmux CLI