Appending environmental varibles programmatically to current process

Question

Main intention is to set the environment variables through java code.

Process process = Runtime.getRuntime().exec("export MY_ENV=123");

Always returns a new process. But I want it to be executed for the current process .. Is there a way to append output to the current process?

See also [When Runtime.exec() won't](http://www.javaworld.com/article/2071275/core-java/when-runtime-exec---won-t.html) for many good tips on creating and handling a process correctly. Then ignore it refers to `exec` and use a `ProcessBuilder` to create the process. — Andrew Thompson, Oct 07 '14 at 19:13
This has been answered [over here](http://stackoverflow.com/questions/318239/how-do-i-set-environment-variables-from-java). It's not a good idea to change the whole question like that. I suggest you revert your edit. — aioobe, Oct 08 '14 at 17:48

score 3 · Accepted Answer · answered Oct 07 '14 at 13:15

3

inheritIO lets you hook up the streams of the started process with the current process
waitFor allows you to wait for the external process to finish

Example:

new ProcessBuilder("/bin/ls").inheritIO()
                             .start()
                             .waitFor();

answered Oct 07 '14 at 13:15

aioobe

score 0 · Answer 2 · answered Oct 07 '14 at 13:13

The Process returned from the exec call contains three streams:

process.getOutputStream() which, if you write to, will be 'piped' in to the running process
process.getInputStream() which, if read from, will contain the standard output (the ls output)
process.getErrorStream() whihc, if read from, will contain the standard error output (error messages from running ls, if any).

It is your responsibility as the programmer, to read from these streams, and to output them to your program's output, if that's what you want.

Also, you should check the process.exitValue() if you want to get that too.

it is somewhat common to set up separate threads to monitor the Stdout and Stderr streams

2 Answers2