|| operator in Gradle Task commandLine

Question

Good day. It is necessary to make a decision to run the second command based on the results of the previous one.

I need to check if npm package is installed and if it doesn't exist start installing. npm list -g package (if the package does not exist, this command will return a value different from 0) and npm install -g package commands are used for the issue. It is easy to execute the logic in a terminal using || operator:

npm list -g package || npm install -g package

Then I created installPackage task in gradle.build file:

task installPackage(type: Exec) {
  commandLine 'npm', 'list', '-g', 'package', '||', 'npm', 'install', '-g', 'package'
}

And none of the commands work. In fact, the result is displayed as if npm list -g command was used.

Is there a way to do this without using third-party tools or plugins? What options could be used? Thanks a lot

Answer 1

There is a question about execute multiple commands Gradle -- execute multiple commands from task, but it doesn't support && or ||. Just pick from below solutions that make sense to you. Personally I prefer solution 1.

1. Put your command in a script and call the script

• More flexible
• More readable (as you don't need to use ',' to separate the command)
• But need to refer to another file

task installPackageWithScript(type: Exec) {
    commandLine('sh', './bin/installPackage.sh')
}

2. Refer to Gradle - How to execute command line in doLast and get exit code?, get the exit code from first command to determine whether second command is needed.

• No need to refer other file
• But less readable and maintainable

task installPackageInline(type: Exec) {
    commandLine('npm', 'list', '-g', 'package')
    doLast {
        if (execResult.exitValue == 0) {
            println "list Success"
        } else {
            println "list Fail, run install"
            exec { commandLine('npm', 'install', '-g', 'package') }
        }
    }
}