Scala - shell commands with pipe

Question

I'm a Scala beginner and I'm writing a wrapper for invoking shell commands. Currently I'm trying to invoke shell commands with pipes from a specified directory.

To achieve this I wrote simple utility:

def runCommand(command: String, directory: File): (Int, String, String) = {

  val errbuffer = new StringBuffer();
  val outbuffer = new StringBuffer();

  //run the command
  val ret = sys.process.Process(command, directory) !
  //log output and err
  ProcessLogger(outbuffer append _ + "\n", outbuffer append _ + "\n");

  return (ret, outbuffer.toString(), errbuffer.toString());
}

However with this utility I can't use pipes, for example:

runCommand("ps -eF | grep -i foo", new File("."));

First I thought, that pipes are shell's functionality, so I tried "/bin/sh -c ps -eF | grep -i foo", but it seems that expression from the right of the pipe was ignored.

I also tried running commands with ! syntax (sys.process._ package), but I couldn't figure out, how to call command from specified directory (without using "cd").

Could you please advice me, how to do this correctly?

@xhochy OK. I removed the comment so that nobody can accidentaly use it. :) — user744186
– user744186, Commented Oct 7, 2012 at 20:35

Uwe L. Korn · Accepted Answer · 2012-10-08 06:34:02Z

9

Change

val ret = sys.process.Process(command, directory) !

to

val ret = sys.process.stringSeqToProcess(Seq("/bin/bash", "-c", "cd " + directory.getAbsolutePath + ";" + command))

Or you could directly use the magic provided by Scala:

import.scala.sys.process._
val ret = "ps -ef" #| "grep -i foo" !

edited Oct 8, 2012 at 6:34

answered Oct 7, 2012 at 20:32

Uwe L. Korn

8,9341 gold badge37 silver badges45 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Sebastian Łaskawiec Over a year ago

Unfortunately it didn't work. I get this error: -eF: -c: line 0: unexpected EOF while looking for matching `'' -eF: -c: line 1: syntax error: unexpected end of file

Uwe L. Korn Over a year ago

@altanis Oh, Scala seems to remove the ' ticks sometimes. I updated my answer with a solution that should work (I think the best would be to use the Scala magic where you enter the pipe as a function (the last example).

Rogach Over a year ago

@altanis - Seems you have a redundant quote in your command. Try printing the directory.getAbsolutePath + ";" + command to output, maybe that would solve it.

Uwe L. Korn Over a year ago

@Rogach The first comment of altanis refers to an older answer of mine. In the updated version this problem should be gone.

Sebastian Łaskawiec Over a year ago

@xhochy Thanks, now it works correctly. The only thing that I changed is: /bin/bash -> /bin/sh.

|

Collectives™ on Stack Overflow

Scala - shell commands with pipe

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related