Creates a process and launches an exectuable with arguments.

Process+Run.swift

// Copyright © 2022 Alex Kovács. All rights reserved.

#if os(macOS)

import Foundation

extension Process {

    /// Creates a process and launches an exectuable with arguments.
    ///
    /// Optionally pass environment variables for the process.
    /// - Parameters:
    ///   - launchPath: Absolute path to an exectuable. E.g., `/usr/bin/git` (not `git`).
    ///   - arguments: Array of command line arguments to pass to the executable. E.g., `["clone", "[email protected]:EbookFoundation/free-programming-books.git", "/Users/alex/Desktop"]`.
    ///   - environment: Dictionary of environment variables and their values.
    ///   - routeStdErrToStdOut: If `true`, `stderr` will be routed to `stdout` (same as `2>&1` on the command line).
    /// - Returns: Output to `stdout`, output to `stderr`, and the termination status code of the executable.
    public static func run(_ launchPath: String, _ arguments: [String] = [], _ environment: [String: String]? = nil, routeStdErrToStdOut: Bool = false) throws -> ProcessExecutionResult {
        let task = Process()
        task.executableURL = URL(filePath: launchPath)
        task.arguments = arguments

        task.environment = environment
        let standardOutputPipe = Pipe()
        task.standardOutput = standardOutputPipe

        let standardErrorPipe = routeStdErrToStdOut ? standardOutputPipe : Pipe()
        task.standardError = standardErrorPipe

        try task.run()
        task.waitUntilExit()

        return .init(
            output: try standardOutputPipe.fileHandleForReading.readToEnd().map { String(data: $0, encoding: .utf8)! },
            error: try standardErrorPipe.fileHandleForReading.readToEnd().map { String(data: $0, encoding: .utf8)! },
            status: Int(task.terminationStatus)
        )
    }

    /// Same as ``run(_:_:_:routeStdErrToStdOut:input:)`` but defaulting the `launchPath` to `/bin/bash`.
    ///
    /// For example:
    /// ```
    /// let result = try Process.runScript(arguments: ["Hello, Argument!"]) {"""
    ///     echo $0
    ///     """}
    /// ```
    /// - Parameters:
    ///   - switch: The switch for the shell to take input via a string. Defaults to `"-c"` which is the option of Bash to read commands from the following  string.
    ///   - script: A closure returning a script string.
    public static func runScript(_ launchPath: String = "/bin/bash", _ switch: String = "-c", arguments: [String] = [], _ environment: [String: String]? = nil, routeStdErrToStdOut: Bool = false, script: () -> String) throws -> ProcessExecutionResult {
        let arguments = [`switch`, script()] + arguments
        return try run(launchPath, arguments, environment, routeStdErrToStdOut: routeStdErrToStdOut)
    }
}

/// The result of executing a process.
public struct ProcessExecutionResult {
    
    /// The output to standard output of the executable.
    var output: String?
    
    /// The output to standard error of the executable.
    var error: String?
    
    /// The termination status code of the executable.
    var status: Int
}

extension ProcessExecutionResult: Equatable {}
extension ProcessExecutionResult: Hashable {}

#endif