I work with Amazon Linux instances and I have a couple scripts to populate data and install all the programs I work with, but a couple of the programs ask:
Do you want to continue [Y/n]? and pause the install. I want to auto answer "Y" in all cases, I'm just now sure how to do it.
The 'yes' command will echo 'y' (or whatever you ask it to) indefinitely. Use it as:
yes | command-that-asks-for-input or, if a capital 'Y' is required:
yes Y | command-that-asks-for-input If you want to pass 'N' you can still use yes:
yes N | command-that-asks-for-input 
yes as it is known to max out the CPU. stackoverflow.com/a/18164007/720665
-y for bash scripts was HARD.
/dev/null or STDOUT. Piped to a command, it will only write one line to the pipe each time the receiving command reads one, and will wait otherwise.echo y | command should work.
Also, some installers have an "auto-yes" flag. It's -y for apt-get on Ubuntu.
-f (--force) flag which works as "auto-yes" for commands that remove something
echo y | pip uninstall psycopg2-binary
yes | foo did not. I needed to run a command like this multiple times in my automation. the yes | foo approach broke after one command was run. The echo Y | foo approach worked for each line!You might not have the ability to install Expect on the target server. This is often the case when one writes, say, a Jenkins job.
If so, I would consider something like the answer to the following on askubuntu.com:
https://askubuntu.com/questions/338857/automatically-enter-input-in-command-line
printf 'y\nyes\nno\nmaybe\n' | ./script_that_needs_user_input Note that in some rare cases the command does not require the user to press enter after the character. in that case leave the newlines out:
printf 'yyy' | ./script_that_needs_user_input For sake of completeness you can also use a here document:
./script_that_needs_user_input << EOF y y y EOF Or if your shell supports it a here string:
./script <<< "y y y " Or you can create a file with one input per line:
./script < inputfile Again, all credit for this answer goes to the author of the answer on askubuntu.com, lesmana.
You just need to put -y with the install command.
For example: yum install <package_to_install> -y
Although this may be more complicated/heavier-weight than you want, one very flexible way to do it is using something like Expect (or one of the derivatives in another programming language).
Expect is a language designed specifically to control text-based applications, which is exactly what you are looking to do. If you end up needing to do something more complicated (like with logic to actually decide what to do/answer next), Expect is the way to go.
If you want to just accept defaults you can use:
\n | ./shell_being_run 
bash, sh and most system, which I know, you need to echo the \n otherwise it would not be piped to the next command.Just do this:
echo y | <your_command>
For example: echo y | apt-get update
We could also time the sequence, with only echo and shell substitution.
The following example dispatch y (yes), wait 3 seconds, answer n (no), wait 3 seconds, and press ENTER:
(echo -n "y"; sleep 3; echo -n "n" ; sleep 3; echo -n "\n") | program 
--nopromptor--noconfirmflag you can use.