Execute a command in Linux using Java and fetch the output

Question

I am using Groovy to execute commands on my Linux box and get back the output, but I am not able to use | pipes somehow (I think) or maybe it is not waiting for

Answer 1

You cannot do pipes or redirects using String.execute(). This doesn't work in Java, so it doesn't work in Groovy either...

You can use Process.pipeTo with Groovy to simplify things:

Process proca = 'uname -a'.execute()
Process procb = 'awk {print\$2}'.execute()

(proca | procb).text

A more generic version could be:

String process = 'uname -a | awk {print\$2}'

// Split the string into sections based on |
// And pipe the results together
Process result = process.tokenize( '|' ).inject( null ) { p, c ->
  if( p )
    p | c.execute()
  else
    c.execute()
}
// Print out the output and error streams
result.waitForProcessOutput( System.out, System.out )