我有一个SBT项目，其中有一个自定义任务，会执行一些操作，然后把结果回显到控制台。

build.sbt:

lazy val myTask = taskKey[Unit]("my custom task")
myTask := {
  // Calls a separate shell script
  s"${baseDirectory.value.getAbsolutePath}/my_task.sh" !
}

my_task.sh:

#!/usr/bin/env bash

# Do some stuff

echo "Successfully did the thing"

目前，这会把 “Successfully did the thing” 直接输出到控制台。

有没有办法让脚本输出到SBT的信息日志，而不是输出到控制台？这看起来是查看这类信息的更合适的地方，而且它还可以通过SBT的 --warn 标志按调用来改变本次运行的日志级别，从而实现逐次静默。

Current output:

$ sbt myTask
[info] welcome to sbt 1.9.8 (Eclipse Adoptium Java 17.0.12)
[info] loading global plugins from /Users/Me/.sbt/1.0/plugins
[info] loading settings for project my-project from meta-build.sbt,plugins.sbt ...
[info] loading project definition from /Users/Me/my-project
[info] resolving key references (14866 settings) ...
[info] set current project to my-project (in build file:/Users/Me/my-project/)
Successfully did the thing

Desired output:

$ sbt myTask
[info] welcome to sbt 1.9.8 (Eclipse Adoptium Java 17.0.12)
[info] loading global plugins from /Users/Me/.sbt/1.0/plugins
[info] loading settings for project my-project from meta-build.sbt,plugins.sbt ...
[info] loading project definition from /Users/Me/my-project
[info] resolving key references (14866 settings) ...
[info] set current project to my-project (in build file:/Users/Me/my-project/)
[info] Successfully did the thing

解决方案

This can be done using the streams.value.log 作为 ! 的日志记录器来实现：

myTask := {
  s"${baseDirectory.value.getAbsolutePath}/my_task.sh" ! streams.value.log
}

This is documented in External Processes in the SBT documentation:

没有参数时，! 方法会把输出发送到标准输出和标准错误。你可以向 ! 方法传入一个 Logger，将输出发送到 Logger：

shell "find project -name *.jar" ! log

你可以通过以下方式获得一个 Logger：

scala val log = streams.value.log