How to Get Exec Output In Kotlin?

12 minutes read

To get the exec output in Kotlin, you can use the Process class, which allows you to start a new process and interact with it. Here's a step-by-step guide:

  1. Import the necessary classes:
1
2
3
import java.lang.ProcessBuilder
import java.io.BufferedReader
import java.io.InputStreamReader


  1. Create a ProcessBuilder object and set the command and arguments:
1
2
3
val command = "<your-executable-command>"
val arguments = listOf("<arg1>", "<arg2>")
val processBuilder = ProcessBuilder(command, *arguments.toTypedArray())


  1. Start the process:
1
val process = processBuilder.start()


  1. Read the output from the process:
1
2
3
4
5
6
7
8
9
val reader = BufferedReader(InputStreamReader(process.inputStream))
val output = StringBuilder()

var line: String?
while (reader.readLine().also { line = it } != null) {
    output.appendln(line)
}

reader.close()


  1. Wait for the process to complete and get the exit code:
1
val exitCode = process.waitFor()


The output variable will contain the output generated by the executed command. If you want to get the error output, you can use process.errorStream instead of process.inputStream.


Note: Remember to handle any exceptions that may be thrown during the process execution.


That's it! You can now use the output variable to access the exec output within your Kotlin code.

Best Kotlin Books to Read in 2024

1
Atomic Kotlin

Rating is 5 out of 5

Atomic Kotlin

2
Head First Android Development: A Learner's Guide to Building Android Apps with Kotlin

Rating is 4.9 out of 5

Head First Android Development: A Learner's Guide to Building Android Apps with Kotlin

3
Kotlin Programming: The Big Nerd Ranch Guide (Big Nerd Ranch Guides)

Rating is 4.8 out of 5

Kotlin Programming: The Big Nerd Ranch Guide (Big Nerd Ranch Guides)

4
Kotlin in Action

Rating is 4.7 out of 5

Kotlin in Action

5
Kotlin Design Patterns and Best Practices: Build scalable applications using traditional, reactive, and concurrent design patterns in Kotlin, 2nd Edition

Rating is 4.6 out of 5

Kotlin Design Patterns and Best Practices: Build scalable applications using traditional, reactive, and concurrent design patterns in Kotlin, 2nd Edition

6
Head First Kotlin: A Brain-Friendly Guide

Rating is 4.5 out of 5

Head First Kotlin: A Brain-Friendly Guide

7
Kotlin Cookbook: A Problem-Focused Approach

Rating is 4.4 out of 5

Kotlin Cookbook: A Problem-Focused Approach

8
How to Build Android Apps with Kotlin: A practical guide to developing, testing, and publishing your first Android apps, 2nd Edition

Rating is 4.3 out of 5

How to Build Android Apps with Kotlin: A practical guide to developing, testing, and publishing your first Android apps, 2nd Edition

9
Modern Android 13 Development Cookbook: Over 70 recipes to solve Android development issues and create better apps with Kotlin and Jetpack Compose

Rating is 4.2 out of 5

Modern Android 13 Development Cookbook: Over 70 recipes to solve Android development issues and create better apps with Kotlin and Jetpack Compose

10
Java to Kotlin: A Refactoring Guidebook

Rating is 4.1 out of 5

Java to Kotlin: A Refactoring Guidebook


How can I run a command and retrieve its output in Kotlin?

In Kotlin, you can use the ProcessBuilder class to run a command and retrieve its output. Here's an example:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
import java.io.BufferedReader
import java.io.InputStreamReader

fun main() {
    val command = "ls" // replace with your desired command
    
    // Create a new process builder
    val processBuilder = ProcessBuilder(command.split(" "))
    
    // Redirect the standard output of the process
    processBuilder.redirectOutput(ProcessBuilder.Redirect.PIPE)
    
    // Start the process
    val process = processBuilder.start()
    
    // Access the output of the process
    val output = process.inputStream.bufferedReader().use(BufferedReader::readText)
    
    // Print the output
    println(output)
}


In this example, the ProcessBuilder is used to create a new process with the specified command. The standard output of the process is redirected to a pipe, and the process is started using the start() method.


To access the output of the process, you can get the input stream of the process using process.inputStream and wrap it in a BufferedReader. Then, you can use the use function to read the entire output as a string.


Finally, you can do whatever you want with the output, such as printing it to the console.


Note that in this example, the command is set to "ls", which lists the files and directories in the current directory. You can replace it with any command you want to run.


How to call an external command and receive its output in Kotlin?

To call an external command and receive its output in Kotlin, you can use the ProcessBuilder class and its inheritIO() method. Here's an example:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
import java.io.BufferedReader
import java.io.InputStreamReader

fun main() {
    val command = "ls -l" // Replace with your desired command
    val process = ProcessBuilder(*command.split(" ").toTypedArray())
        .inheritIO()
        .start()
    val reader = BufferedReader(InputStreamReader(process.inputStream))
    var line: String?
    while (reader.readLine().also { line = it } != null) {
        println(line)
    }

    val exitCode = process.waitFor()
    println("External command exited with code $exitCode")
}


In this example, the command variable contains the command you want to execute. The command is split into an array of strings using the .split(" ") function. Then, a ProcessBuilder instance is created with the command array.


The .inheritIO() method redirects the process's output to the current process's output, so the output of the external command will be displayed in your console.


The .start() method starts the external process, and the inputStream property of the process is used to read its output. We create a BufferedReader and loop through each line of the output using readLine(). Finally, we wait for the external command to finish using .waitFor() and print its exit code.


Replace "ls -l" with the desired command you want to execute.


How to invoke a command and retrieve its output in Kotlin?

In Kotlin, you can use the ProcessBuilder class to invoke a command and retrieve its output. Here's an example:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
import java.io.BufferedReader
import java.io.InputStreamReader

fun main() {
    val command = "ls -l"  // Replace with your desired command
    
    val process = ProcessBuilder(command.split(" "))
        .redirectOutput(ProcessBuilder.Redirect.PIPE)
        .start()
    
    val output = process.inputStream.bufferedReader().use(BufferedReader::readText)
    
    println("Command output:\n$output")
}


In this example, we use the ProcessBuilder to start a process with the desired command. We redirect the output of the process to a pipe and then read the output using a BufferedReader.


Note that you need to specify the command you want to invoke by replacing "ls -l" in the above example. This is just an example command to list files in the current directory.


How to extract exec output in Kotlin?

In Kotlin, you can use the ProcessBuilder class to execute a command and then extract the output. Here is an example:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
import java.io.BufferedReader
import java.io.InputStreamReader

fun main() {
    val command = "ls"

    val process = ProcessBuilder(command)
        .redirectErrorStream(true)
        .start()

    val outputStream = process.inputStream
    val reader = BufferedReader(InputStreamReader(outputStream))
    var line: String?

    while (reader.readLine().also { line = it } != null) {
        println(line)
    }

    val exitCode = process.waitFor()
    println("Exit code: $exitCode")
}


In this example, we are executing the "ls" command and printing the output to the console. The redirectErrorStream(true) method ensures that the error stream is merged with the input stream so that we can read both streams from the same InputStream. The waitFor() method is used to wait for the process to complete and get the exit code.


You can replace the "ls" command with any other command you want to execute.


What is the recommended way to retrieve exec output in Kotlin?

In Kotlin, you can retrieve the output of an executed command by using the ProcessBuilder class from the Java standard library. Here's an example:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
import java.io.BufferedReader
import java.io.InputStreamReader

fun main() {
    val command = "ls" // Replace with your desired command
    
    val process = ProcessBuilder(command.split("\\s".toRegex())) // Splits the command into individual arguments
        .redirectOutput(ProcessBuilder.Redirect.PIPE) // Redirects the output to a pipe
        .start() // Starts the process
        
    val reader = BufferedReader(InputStreamReader(process.inputStream))
    var line: String?
    
    while (reader.readLine().also { line = it } != null) {
        println(line) // Prints each line of output
    }
    
    // Waits for the process to complete
    val exitCode = process.waitFor() 
    
    println("Process exit code: $exitCode")
}


In this example, the ProcessBuilder is used to create and start a process with the specified command. The output of the process is then redirected to an input stream, which is read line by line using a BufferedReader. Each line of output is printed, and the process's exit code is retrieved using process.waitFor().


You can replace the command variable with your desired command, such as "echo Hello, World!" or any other executable command.


How to access exec output in Kotlin?

To access the output of an executed command in Kotlin, you can use the Runtime.getRuntime().exec() method. Here's an example of how you can do it:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
import java.io.BufferedReader
import java.io.InputStreamReader

fun main() {
    val command = "ls" // Replace it with your desired command

    val process = Runtime.getRuntime().exec(command)

    val output = StringBuffer()
    val reader = BufferedReader(InputStreamReader(process.inputStream))
    var line: String?
    while (reader.readLine().also { line = it } != null) {
        output.append("$line\n")
    }
    val result = output.toString()

    println(result)
}


In this example, we execute the ls command to list the files and directories in the current directory. The output of the executed command is read line by line from the process's input stream and stored in the output StringBuffer. Finally, we convert the contents of output to a String using toString() and print it.


Note: Depending on the command you are executing, you may need to handle the error stream as well by reading from process.errorStream in a similar way.

Facebook Twitter LinkedIn Whatsapp Pocket

Related Posts:

To execute terminal commands from Golang, you can use the os/exec package which allows executing system commands. Here is a simple approach to achieving this:Import the necessary package: import &#34;os/exec&#34; Use the Command function from os/exec to create...
To pass a variable value to a shell script from Go, you can use the os/exec package in Go. The following steps outline how you can achieve this:Import the necessary packages: import ( &#34;os&#34; &#34;os/exec&#34; ) Set the variable value in Go: variable :=...
To multiply a list in Kotlin, you can use the map function along with the &#34;*&#34; operator. Here&#39;s an example: fun main() { val numbers = listOf(1, 2, 3, 4, 5) val multipliedNumbers = numbers.map { it * 2 } println(multipliedNumbe...