New Post: ShellStream, end of command / waiting for input

Hi all, this project is the backbone to some pretty nice automation tools on our end, so thanks very much.

One thing I do is interact with a shell-within-a-shell program - think irb or python shell on Unix system. I have APIs which emulate sending commands and receiving response from this shell as well as from the Unix prompt.

Is there a clean way to detect the state in the ShellStream which indicates the shell is waiting for user input, whether it's the Unix prompt or other (irb/Python, or even a custom ANSI menu app)? Even just a solution for the Unix prompt would be very useful.

A trivial example would be a Unix shell with a dynamic prompt, say it contains the current working directory name. I can figure out what the prompt is initially, and train the API to expect it as the 'last' output from the stream, but if I cd somewhere it throws everything off. I can use a special 'cd' API to re-detect the new prompt but that's an additional delay to read the stream for the new prompt (and not too clean a solution).

e.g.

string prompt = my_api.detect_prompt();
my_api.send_command("ls -lp\r");
string output1 = my_api.read_until_encounter(prompt); // read until we encounter the prompt string

my_api.send_command("cd /tmp/my_directory\r");
prompt = my_api.detect_prompt(); // re-learn prompt because it changed from /home/user> to /tmp/my_directory>

my_api.send_command("ls -lp\r");
string output2 = my_api.read_until_encounter(prompt);

replaced by

my_api.send_command("cd /tmp/my_dir\r");
string output 3 = my_api.read_everything(); // smart enough to identify EOF equivalent