Suppress Gradle's JavaExec output - gradle

Question

I have gradle code below and I don't know how to avoid huge output generated by JavaExec task. I haven't found any option of JavaExec for it. If anyone knows better way of ignoring it, please share it.
def getStubOutput() {
return new FileOutputStream(new File("${buildDir}/temp"))
}
configure(project(':jradius:dictionary-min')) {
evaluationDependsOn(':jradius')
sourceSets {
main {
java {
srcDir "${projectDir}/target/dictionary-src"
}
}
}
dependencies {
compile project(':jradius:core')
}
task genSources(type: JavaExec) {
main = 'net.jradius.freeradius.RadiusDictionary'
classpath configurations.all
args = ["net.jradius.dictionary", "${projectDir}/../freeradius/dict-min", "${projectDir}/target/dictionary-src"]
maxHeapSize = "800m"
standardOutput = getStubOutput()
}
jar {
archiveName = "jradius-dictionary-min-1.1.5-SNAPSHOT.jar"
}
genSources.dependsOn ':jradius:cloneJradius'
compileJava.dependsOn genSources
}

Answer 1

I simply use a dummy OutputStream that does nothing in its write method:
def dummyOutputStream = new OutputStream() {
#Override
public void write(int b) {}
}
exec {
executable = name
standardOutput = dummyOutputStream
errorOutput = dummyOutputStream
ignoreExitValue = true
}

Answer 2

A great solution I came across is to modify the logging level of the task. If you set it to INFO, then it will squelch all the output of that task, unless gradle is run with --info.
Alternatively, you can set the level to LogLevel.QUIET, which will completely silence it.
task chatty(type: Exec) {
....
logging.captureStandardOutput LogLevel.INFO
}

Answer 3

As in the comment I thought that standardOutput can be set to null but the following piece of code (taken from: org.gradle.process.internal.AbstractExecHandleBuilder) shows that's not possible:
public AbstractExecHandleBuilder setStandardOutput(OutputStream outputStream) {
if (outputStream == null) {
throw new IllegalArgumentException("outputStream == null!");
}
this.standardOutput = outputStream;
return this;
}
What You can do is to redirect the output to temporary file (file will be deleted!) with this oneliner:
task genSources(type: JavaExec) {
main = 'net.jradius.freeradius.RadiusDictionary'
classpath configurations.all
args = ["net.jradius.dictionary", "${projectDir}/../freeradius/dict-min", "${projectDir}/target/dictionary-src"]
maxHeapSize = "800m"
standardOutput = { def f = File.createTempFile('aaa', 'bbb' ); f.deleteOnExit(); f.newOutputStream() }()
}
or if You'd like to save this output for further reading:
task genSources(type: JavaExec) {
main = 'net.jradius.freeradius.RadiusDictionary'
classpath configurations.all
args = ["net.jradius.dictionary", "${projectDir}/../freeradius/dict-min", "${projectDir}/target/dictionary-src"]
maxHeapSize = "800m"
standardOutput = new File(project.buildDir, 'radius.log').newOutputStream()
}
The last option is to add apache commons-io to script dependencies and set standardOutput to NullOutputStream. In can be done as follows:
import static org.apache.commons.io.output.NullOutputStream.NULL_OUTPUT_STREAM
buildscript {
repositories {
mavenCentral()
}
dependencies {
classpath 'commons-io:commons-io:2.4'
}
}
task genSources(type: JavaExec) {
main = 'net.jradius.freeradius.RadiusDictionary'
classpath configurations.all
args = ["net.jradius.dictionary", "${projectDir}/../freeradius/dict-min", "${projectDir}/target/dictionary-src"]
maxHeapSize = "800m"
standardOutput = NULL_OUTPUT_STREAM
}
That's all that comes to my head.

Answer 4

This disables the standard output from a javaExec task:
task myCustomTask(type: javaExec) {
standardOutput = new ByteArrayOutputStream()
classpath = ...
main = ...
args ....
}