Executing bash strings using scala.sys.process

Question

I recently discovered sys.process package in Scala, and was amused by its power.

But when I try to combine it with bash pipes and backticks, I get stuck.

This obviously doesn't work:

scala> "echo `date`" !!
res0: String = "
"`date`
"

I tried to use the bash executable to get the desired behavior:

scala> "bash -e echo `date`" !!
/bin/echo: /bin/echo: cannot execute binary file
java.lang.RuntimeException: Nonzero exit value: 126

What am I doing wrong?

Edit:

scala> "bash -ic 'echo `date`'" !!
`date`': unexpected EOF while looking for matching `''
`date`': syntax error: unexpected end of file
 java.lang.RuntimeException: Nonzero exit value: 1

Informative example, but I hope you realise you don't need bash at all for this: Seq("date")!! — Todd Owen
– Todd Owen, Commented Jan 12, 2016 at 0:14

Kim Stebel · Accepted Answer · 2011-12-04 15:42:43Z

22

You're doing multiple things wrong actually. You should be using the -c option of bash and you should be using a Seq[String] with each parameter to bash in its own String, or the scala library will just split the String at every space character. (This is why Rex Kerr's solution doesn't work.)

scala> import sys.process.stringSeqToProcess
import sys.process.stringSeqToProcess

scala> Seq("bash", "-c", "echo `date`")!!
res20: String = 
"Sun Dec 4 16:40:04 CET 2011
"

answered Dec 4, 2011 at 15:42

Kim Stebel

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2 Comments

Rex Kerr Over a year ago

Good point about the Seq version. I actually used that one instead, since I always do, and never checked the single-string version!

Nick Over a year ago

Here is another example executing a script and with args to follow. IE: test.sh echo $1 scala> Seq("/somePath/test.sh"," HI")! credit due to here: stackoverflow.com/questions/9039167/…

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