Capturing stdout when calling Runtime.exec

Question

When experiencing networking problems on client machines, I'd like to be able to run a few command lines and email the results of them to myself.

I've found Runtime.exec will allow me to execute arbitrary commands, but Collecting the results in a String is more interesting.

I realize I could redirect output to a file, and then read from the file, but my spidey sense is telling me there's a more elegant way of doing it.

Suggestions?

Answer 1

You need to capture both the std out and std err in the process. You can then write std out to a file/mail or similar.

See this article for more info, and in particular note the StreamGobbler mechanism that captures stdout/err in separate threads. This is essential to prevent blocking and is the source of numerous errors if you don't do it properly!

Answer 2

Use ProcessBuilder. After calling start() you'll get a Process object from which you can get the stderr and stdout streams.

UPDATE: ProcessBuilder gives you more control; You don't have to use it but I find it easier in the long run. Especially the ability to redirect stderr to stdout which means you only have to suck down one stream.