Question

My program runs(exec..) an external program.
While running, the external program asks user [Yes/No] to proceed next step.

Instead of typing [yes] in command line, how can I pass [Yes] to the external program from my program.

Answer 1

Unless the external program supports a respective flag (see @Jonathan Leffler’s answer), your you have control over that program’s source and can add it, you have to simulate the “yes” input.

Options:

• Try launching the external program by piping the output of the yes helper application to it’s stdin: yes | external_program. yes is a simple tool, should you not have it, that just writes “y” to it’s stdout continually.

• Manually write “yes” to to stdin of the external program.

Both options require your to use pipes in one way or the other. See this for more information on how to do that.