Respond to Prompt in Bash Script
I work on a project that requires I frequently build and destroy a virtual machine. I don't enjoy having to do so but virtual machines can be notoriously difficult to prop up, especially when you have a complex app living within it.
Manually typing the same commands over and over can be mind-numbing so I've create a bash script to handle all of the work for me. One hiccup to the process is needing to confirm removal of an existing virtual machine; using a pipe and echo allows me to answer the prompt:
# ... some directives here
# Remove the machine, confirming "y" when asked by docker-machine
echo 'y' | docker-machine rm default
# ... more directives here
Using echo I pipe a y response to docker-machine's confirmation prompt, thus allowing the script to move forward with other tasks without the need for manual intervention.
I don't, however, know how to handle multiple prompts -- can you tell me and everyone else?
![CSS Animations Between Media Queries]()
CSS animations are right up there with sliced bread. CSS animations are efficient because they can be hardware accelerated, they require no JavaScript overhead, and they are composed of very little CSS code. Quite often we add CSS transforms to elements via CSS during...
![5 HTML5 APIs You Didn’t Know Existed]()
When you say or read "HTML5", you half expect exotic dancers and unicorns to walk into the room to the tune of "I'm Sexy and I Know It." Can you blame us though? We watched the fundamental APIs stagnate for so long that a basic feature...
![MooTools Fun with Fx.Shake]()
Adding movement to your website is a great way to attract attention to specific elements that you want users to notice. Of course you could use Flash or an animated GIF to achieve the movement effect but graphics can be difficult to maintain. Enter...
![Add Site Screenshots for External Links Using MooTools Tooltips]()
Before you send your user to an unknown external website, why not provide them a screenshot of the site via a tooltip so they may preview the upcoming page? Here's how you can do just that using MooTools.
The MooTools JavaScript
The first step is to grab...
As far as I know this is usually done with the yes command:
This should also respond to multiple prompts.
Ah yes, I did experiment with that. But what if I know the multiple prompt responses should be “y”, “n”, “3”? That would be useful.
To expand on what Andreas said, you can build a canned file of responses, one per line (extra blanks for the equivalent of hitting enter) and sending that to your program:
Can’t you stream a file in? Like in
Try a here string.
while IFS= read -r; do echo "E- $REPLY" done <<<"y n 3"Will print the three lines of responses. Assuming the docker prompt is similar to read it should work.
The ‘expect’ utility can be installed on most Linux boxes.
https://en.wikipedia.org/wiki/Expect
I agree about ‘expect’ as Rohit mentions, it’s usually what you resort to when piping doesn’t work for different reasons (such as passwords being read from physical terminal only, input being prematurely consumed by a loop, etc).
The tool is {advanced|complicated} enough to maybe warrant a future post ;-)
In my team we use Vagrant and Ansible to do these kinds of things. They are very helpful tool for popping up a dev env with customized apps / configs.
I have not tried Ansible for Docker but there is a page for it https://www.ansible.com/docker