Verbosity

Logging in Scala CLI can be controlled in a number of ways.

println("Hello")

Logs, warnings and errors will be printed by default.

scala-cli Hello.sc

Compiling project (Scala 3.2.2, JVM)
Compiled project (Scala 3.2.2, JVM)
Hello

Silencing logs with -q

All logs except for errors can be silenced by passing the -q option.

scala-cli Hello.sc -q

Hello

Increasing verbosity with -v

You can increase verbosity by passing the -v option, to print debugging logs or gain extra context.

scala-cli Hello.sc -v

Compiling project (Scala 3.2.2, JVM)
Compiled project (Scala 3.2.2, JVM)
Running ~/Library/Java/JavaVirtualMachines/corretto-17.0.5/Contents/Home/bin/java -cp ~/IdeaProjects/scala-cli-tests/hello1/.scala-build/project_853f6d1dbb-28a878fa14/classes/main:~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala3-library_3/3.2.2/scala3-library_3-3.2.2.jar:~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala-library/2.13.10/scala-library-2.13.10.jar Hello_sc
Hello

You can increase verbosity even further by passing the -v option multiple times.

scala-cli Hello.sc -v -v

Fetching List(Dependency(org.scala-lang:scala3-compiler_3, 3.2.2, Configuration(), Set(), Publication(, Type(), Extension(), Classifier()), false, true)), adding List(IvyRepository(Pattern(List(Const(file://~/Library/Caches/ScalaCli/local-repo/v0.2.0//), Var(organisation), Const(/), Var(module), Const(/), Opt(List(Const(scala_), Var(scalaVersion), Const(/))), Opt(List(Const(sbt_), Var(sbtVersion), Const(/))), Var(revision), Const(/), Var(type), Const(s/), Var(artifact), Opt(List(Const(-), Var(classifier))), Const(.), Var(ext))), None, None, true, true, true, false, None, true))
Found 13 artifacts:
  ~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala3-compiler_3/3.2.2/scala3-compiler_3-3.2.2.jar
  ~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala3-interfaces/3.2.2/scala3-interfaces-3.2.2.jar
  ~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala3-library_3/3.2.2/scala3-library_3-3.2.2.jar
  ~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/tasty-core_3/3.2.2/tasty-core_3-3.2.2.jar
  ~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/modules/scala-asm/9.3.0-scala-1/scala-asm-9.3.0-scala-1.jar
  ~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-sbt/compiler-interface/1.3.5/compiler-interface-1.3.5.jar
  ~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/jline/jline-reader/3.19.0/jline-reader-3.19.0.jar
  ~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/jline/jline-terminal/3.19.0/jline-terminal-3.19.0.jar
  ~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/jline/jline-terminal-jna/3.19.0/jline-terminal-jna-3.19.0.jar
  ~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala-library/2.13.10/scala-library-2.13.10.jar
  ~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/com/google/protobuf/protobuf-java/3.7.0/protobuf-java-3.7.0.jar
  ~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/org/scala-sbt/util-interface/1.3.0/util-interface-1.3.0.jar
  ~/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/net/java/dev/jna/jna/5.3.1/jna-5.3.1.jar
(...)
Hello

Warnings suppression

Some specific warning logs can be suppressed individually. That can be done by passing an appropriate option or by setting the appropriate global configuration key.

Warnings about using directives spread in multiple files

//> using dep com.lihaoyi::os-lib:0.9.1

//> using dep com.lihaoyi::pprint:0.8.0

It is generally advised to not spread the using directives in multiple files, and put them in the optional project.scala configuration file. The relevant warnings can be suppressed with the --suppress-warning-directives-in-multiple-files option.

scala-cli Deps1.sc Deps2.sc --suppress-warning-directives-in-multiple-files

Alternatively, the global config key suppress-warning.directives-in-multiple-files can be used.

scala-cli config suppress-warning.directives-in-multiple-files true

Warnings about experimental features' usage

Using experimental features produces warnings, which can be suppressed with the --suppress-experimental-warning option.

scala-cli --power run --suppress-experimental-warning --markdown-snippet '# Markdown snippet
with a code block
```scala
println("Hello")
```'

Alternatively, the global config key suppress-warning.experimental-features can be used.

scala-cli config suppress-warning.experimental-features true

Warnings about having outdated dependencies

//> using dep com.lihaoyi::pprint:0.6.6

Depending on outdated libraries produces warnings, which can be suppressed with the --suppress-outdated-dependencies-warning option.

scala-cli OldDeps.sc --suppress-outdated-dependencies-warning

Alternatively, the global config key suppress-warning.outdated-dependencies-files can be used.

scala-cli config suppress-warning.outdated-dependencies-files true