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?
![An Interview with Eric Meyer]()
Your early CSS books were instrumental in pushing my love for front end technologies. What was it about CSS that you fell in love with and drove you to write about it?
At first blush, it was the simplicity of it as compared to the table-and-spacer...
![Being a Dev Dad]()
I get asked loads of questions every day but I'm always surprised that they're rarely questions about code or even tech -- many of the questions I get are more about non-dev stuff like what my office is like, what software I use, and oftentimes...
![Record Text Selections Using MooTools or jQuery AJAX]()
One technique I'm seeing more and more these days (CNNSI.com, for example) is AJAX recording of selected text. It makes sense -- if you detect users selecting the terms over and over again, you can probably assume your visitors are searching that term on Google...
![Image Protection Using PHP, the GD Library, JavaScript, and XHTML]()
Warning: The demo for this post may brick your browser.
A while back I posted a MooTools plugin called dwProtector that aimed to make image theft more difficult -- NOT PREVENT IT COMPLETELY -- but make it more difficult for the rookie to average user...
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