How do I script a "yes" response for installing programs?

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.

echo y | command should work.

Also, some installers have an "auto-yes" flag. It's -y for apt-get on Ubuntu.

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