Kotlin-native执行命令并获取输出

Question

我想知道在原生kotlin中是否有一种方法可以通过posix调用命令并接收它的终端输出。例如，我想让"git diff“命令工作，而不必创建一个临时文件，将输出写入该文件，然后从该文件读取。

所以我只找到了需要ProcessBuilder的解决方案，这在kotlin-native上是不可用的，因为它是一个Java库。

Answer 1

这是mg-lolenstine发布的Kotlin Native的exec命令的改进版本，它抛出了一个异常，命令stderr而不是只返回exit(1) (这本身并不总是令人满意的行为)，而且trim现在是可选的

import kotlinx.cinterop.*
import platform.posix.*

fun executeCommand(
    command: String,
    trim: Boolean = true,
    redirectStderr: Boolean = true
): String {
    val commandToExecute = if (redirectStderr) "$command 2>&1" else command
    val fp = popen(commandToExecute, "r") ?: error("Failed to run command: $command")

    val stdout = buildString {
        val buffer = ByteArray(4096)
        while (true) {
            val input = fgets(buffer.refTo(0), buffer.size, fp) ?: break
            append(input.toKString())
        }
    }

    val status = pclose(fp)
    if (status != 0) {
        error("Command `$command` failed with status $status${if (redirectStderr) ": $stdout" else ""}")
    }

    return if (trim) stdout.trim() else stdout
}

Answer 2

我找到了一段我想要使用的工作代码，所以我将其发布在这里，供将来的读者使用！

fun executeCommand(command: String): String{
    val fp: CPointer<FILE>? = popen(command, "r")
    val buffer = ByteArray(4096)
    val returnString = StringBuilder()

    /* Open the command for reading. */
    if (fp == NULL) {
        printf("Failed to run command\n" )
        exit(1)
    }

    /* Read the output a line at a time - output it. */
    var scan = fgets(buffer.refTo(0), buffer.size, fp)
    if(scan != null) {
        while (scan != NULL) {
            returnString.append(scan!!.toKString())
            scan = fgets(buffer.refTo(0), buffer.size, fp)
        }
    }
    /* close */
    pclose(fp)
    return returnString.trim().toString()
}

Answer 3

我使用上面的答案创建了一个运行任意本地进程/命令的工作gradle kotlin原生/jvm多平台多项目：

这是我的结果：

https://github.com/hoffipublic/minimal_kotlin_multiplatform

import kotlinx.cinterop.refTo
import kotlinx.cinterop.toKString
import platform.posix.fgets
import platform.posix.pclose
import platform.posix.popen

actual object MppProcess : IMppProcess {
    actual override fun executeCommand(
        command: String,
        redirectStderr: Boolean
    ): String? {
        val commandToExecute = if (redirectStderr) "$command 2>&1" else command
        val fp = popen(commandToExecute, "r") ?: error("Failed to run command: $command")

        val stdout = buildString {
            val buffer = ByteArray(4096)
            while (true) {
                val input = fgets(buffer.refTo(0), buffer.size, fp) ?: break
                append(input.toKString())
            }
        }

        val status = pclose(fp)
        if (status != 0) {
            error("Command `$command` failed with status $status${if (redirectStderr) ": $stdout" else ""}")
        }

        return stdout
    }
}

在jvm上

import java.util.concurrent.TimeUnit

actual object MppProcess : IMppProcess {
    actual override fun executeCommand(
        command: String,
        redirectStderr: Boolean
    ): String? {
        return runCatching {
            ProcessBuilder(command.split(Regex("(?<!(\"|').{0,255}) | (?!.*\\1.*)")))
                //.directory(workingDir)
                .redirectOutput(ProcessBuilder.Redirect.PIPE)
                .apply { if (redirectStderr) this.redirectError(ProcessBuilder.Redirect.PIPE) }
                .start().apply { waitFor(60L, TimeUnit.SECONDS) }
                .inputStream.bufferedReader().readText()
        }.onFailure { it.printStackTrace() }.getOrNull()
    }
}