Groovy executing shell commands

Question

Groovy adds the execute method to String to make executing shells fairly easy   println  ls  execute   text   but if an error happens  then there is no resulting output   Is there an easy way to get both the standard error and standard out    other than creating a bunch of code to  create two threads to read both inputstreams  then using a parent stream to wait for them to complete then convert the strings back to text    It would be nice to have something like    def x   shellDo  ls  tmp NoFile    println  out    x out  err   x err

User · Answer

def exec     encoding  execPath  execStr  execCommands - gt   def outputCatcher   new ByteArrayOutputStream   def errorCatcher   new ByteArrayOutputStream    def proc   execStr execute null  new File execPath   def inputCatcher   proc outputStream  execCommands each   cm - gt      inputCatcher write cm getBytes encoding       inputCatcher flush      proc consumeProcessOutput outputCatcher  errorCatcher  proc waitFor    return  new String outputCatcher toByteArray    encoding   new String errorCatcher toByteArray    encoding       def out   exec  cp866    C   Test    cmd     cd   n    dir n    exit n     println  OUT  n    out 0  println  ERR  n    out 1

User · Answer

Ok  solved it myself  def sout   new StringBuilder    serr   new StringBuilder   def proc    ls  badDir  execute   proc consumeProcessOutput sout  serr  proc waitForOrKill 1000  println  quot out gt   sout nerr gt   serr quot   displays  out gt   err gt  ls  cannot access  badDir  No such file or directory

User · Answer

a wrapper closure around executing a string                                      can take either a string or a list of strings  for arguments with spaces         prints all output  complains and halts on error                               def runCommand     strList - gt    assert   strList instanceof String                 strList instanceof List  amp  amp  strList each  it instanceof String           def proc   strList execute     proc in eachLine   line - gt  println line     proc out close     proc waitFor      print   INFO        if strList instanceof List        strList each   print    it          else       print strList       println         if  proc exitValue          println  gave the following error        println   ERROR    proc getErrorStream           assert  proc exitValue

User · Answer

I find this more idiomatic   def proc    ls foo txt doesnotexist txt  execute   assert proc in text     foo txt n  assert proc err text     ls  doesnotexist txt  No such file or directory n    As another post mentions  these are blocking calls  but since we want to work with the output  this may be necessary

User · Answer

To add one more important information to above provided answers -   For a process  def proc   command execute      always try to use   def outputStream   new StringBuffer    proc waitForProcessOutput outputStream  System err    proc waitForProcessOutput System out  System err    rather than   def output   proc in text    to capture the outputs after executing commands in groovy as the latter is a blocking call  SO question for reason

User · Answer

command    ls     def execute state sh returnStdout  true  script  command    but if the command failure the process will terminate

User · Answer

ls  execute   returns a Process object which is why  ls  execute   text works  You should be able to just read the error stream to determine if there were any errors   There is a extra method on Process that allow you to pass a StringBuffer to retrieve the text  consumeProcessErrorStream StringBuffer error    Example   def proc    ls  execute   def b   new StringBuffer   proc consumeProcessErrorStream b   println proc text println b toString

[groovy] Groovy executing shell commands

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