如何将控制台命令作为字符串返回给正在运行的软件？

Question

Let me give a simple example:
In a Linux environment I have a Grails script, and I want to get all my directories using ls command:

def ls = "ls".execute()
println ls
// result is java.lang.UNIXProcess@f16b42

Instead of getting the process ID, I want to get the same output I get into a terminal

Ps.: This is just a example, I don't really need to list directories.

Answer 1

The quick way is:

String output = 'ls'.execute().text
println output

HOWEVER! If it writes a lot of output, the reader will fill up, and then it will all block. So, you need to do something like:

String output = new StringWriter().with { out ->
    Process proc = 'ls'.execute()
    proc.consumeProcessOutput( out, System.err )
    proc.waitFor()
    out.toString()
}
println output

Of course, you might want to check the exitCode that proc.waitFor() returns, and do something better with the error stream then send it to System.err , but you get the idea ;-)

Answer 2

You can also do something like this.

File directory = new File(args[0])
Process p = "ls".execute([], directory)            
p.waitForProcessOutput(System.out, System.err)         

If this were a script called listFiles.groovy, you could run

groovy listFiles ~/blah

and see everything in the blah directory. This is going to wait for the process to finish before moving onto any other commands.

Check out the groovy docs for Process . There is a lot of fun stuff there.