How to automatically answer interactive cli program (not script) with bash script?

Question

I've googled this, and almost all I could find is to answer a bash script and this doesn't work for me. The answers I found told to do:

echo "yes" | ./script

or

./script <<< yes

or something like that. It didn't work for me. My guess is that's because what I want to do is to auto answer an executable program, not a script. More specifically, I want to auto answer parted. Here

parted -a optimal /dev/sda mklabel msdos
Warning: The existing disk label on /dev/sda will be destroyed and
all data on this disk will be lost. Do you want to continue?
Yes/No? _

I try to do

echo "yes" | parted -a optimal /dev/sda mklabel msdos

and

parted -a optimal /dev/sda mklabel msdos <<< yes

Both methods didn't work. Those didn't answer yes to parted prompt.

So, how can I automatically answer that parted prompt without using a bash script?

Solution

With parted, you can just add the -s option:

parted -a optimal -s /dev/sda mklabel msdos

From the Trusty man page for parted:

[...]
       -s, --script
              never prompts for user intervention
[...]

Comments

[j0h]

There is a language for specifically that purpose, to automate interactive programs. it is called "expect" and you can call it from within a bash script.

[Eliah Kagan]

Related: parted script to automate disk partitioning

[Mas Bagol]

never prompts ... does it means, yes to all?

[A.B.]

@BagolDaplun Never ask in this case means that the default is used.

[kos]

@BagolDaplun As A.B. said -s makes parted use the default (which is yes). Also I corrected the command because here you can't combine options since -a needs an argument.