8

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?

muru
  • 207,228
Mas Bagol
  • 1,399

2 Answers2

11

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
[...]
kos
  • 41,268
0

As of Parted 3.* the accepted answer is no longer true.

Parted is primarily designed to be used in interactive mode where a human will provide information to parted and answer its questions in real-time.

There is also an option to run parted in script-mode parted -s where commands can be fed to parted all in one go without having to interact step by step with parted.

As of Parted 3.* if the aim is to shrink a partition in script-mode parted will prompt for user intervention and then exit. This is intentional, for safety purposes, according to feedback in this bug report which also provides a patch that works around that limitation.

Parted has an undocumented feature ---pretend-input-tty that behaves like script-mode as it also allows for parameters to be fed to it, all together, except it runs parted in interactive mode.

In this code snippet a disk with one partition is mounted at /dev/loop0 and parted will increase and shrink the size of a partition without objection:

echo -e "resizepart 1 46280703s\nyes\nunit s\nprint\nquit" | sudo parted /dev/loop0 ---pretend-input-tty

The expect command could also be used to automate providing information and answers to parted when it is running in interactive mode. This script creates a 100MiB disk image file, creates one partition and formats it as ext4.

#!/bin/bash
#
# Script to make a disk image file
#

Create a 100MiB disk file, when partitioned it will have 204800 sectors


cd ~
dd if=/dev/zero of=disk.img bs=1M count=100


loopdevice=$(losetup --show --find --partscan disk.img)


echo $loopdevice
echo $loopdevice"p1"


parted -s $loopdevice mklabel gpt
parted -s $loopdevice mkpart primary ext4 2048s 100%
mkfs -t ext4 $loopdevice"p1"

Now running this next script will call parted and use expect to feed in answers to increase or decrease that partition without problem:

#!/usr/bin/expect
#
# Script that uses the 'expect' command to feed answers to 'parted' command
# when it is running in interactive mode.
#

spawn sudo parted disk.img
expect "(parted)" {send "p\n"}
expect "(parted)" {send "resizepart 1 150000s\n"}
expect "Yes/No?" {send "y\n"}
expect "(parted)" {send "p\n"}
expect "(parted)" {send "q\n"}
FlexMcMurphy
  • 231