Basta adicionar o parâmetro de inicialização do kernel 'noprompt'. Se você estiver usando o Grub, edite boot / grub / grub.cfg.
Automação da Ubiquity
Nota: não se esqueça de adicionar antes do '---' 
Estou criando uma instalação iso não-adaptada do Xubuntu 17.04. Eu segui a solução aqui e em alguns outros lugares, mas ainda tenho um problema. A instalação pede para remover a mídia e pressionar enter, como pode ser visto aqui . Eu tentei adicionar os comandos abaixo ao meu preseed:
d-i finish-install/reboot_in_progress note
ubiquity finish-install/reboot_in_progress note
ubiquity ubiquity/reboot boolean true
Mas nenhum deles funcionou. Aqui está minha preseed completa:
#### Contents of the preconfiguration file (for xenial)
### Localization
# Preseeding only locale sets language, country and locale.
d-i debian-installer/locale string en_US
d-i languagechooser/language-name string English
# The values can also be preseeded individually for greater flexibility.
#d-i debian-installer/language string en
#d-i debian-installer/country string NL
#d-i debian-installer/locale string en_GB.UTF-8
# Optionally specify additional locales to be generated.
#d-i localechooser/supported-locales multiselect en_US.UTF-8, nl_NL.UTF-8
# Keyboard selection.
# Disable automatic (interactive) keymap detection.
d-i console-setup/ask_detect boolean false
d-i keyboard-configuration/xkb-keymap select br
# To select a variant of the selected layout:
#d-i keyboard-configuration/xkb-keymap select us(dvorak)
# d-i keyboard-configuration/toggle select No toggling
### Network configuration
# Disable network configuration entirely. This is useful for cdrom
# installations on non-networked devices where the network questions,
# warning and long timeouts are a nuisance.
d-i netcfg/enable boolean false
# netcfg will choose an interface that has link if possible. This makes it
# skip displaying a list if there is more than one interface.
d-i netcfg/choose_interface select auto
# To pick a particular interface instead:
#d-i netcfg/choose_interface select eth1
# To set a different link detection timeout (default is 3 seconds).
# Values are interpreted as seconds.
#d-i netcfg/link_wait_timeout string 10
# If you have a slow dhcp server and the installer times out waiting for
# it, this might be useful.
d-i netcfg/dhcp_timeout string 10
d-i netcfg/dhcpv6_timeout string 10
# If you prefer to configure the network manually, uncomment this line and
# the static network configuration below.
#d-i netcfg/disable_autoconfig boolean true
# If you want the preconfiguration file to work on systems both with and
# without a dhcp server, uncomment these lines and the static network
# configuration below.
#d-i netcfg/dhcp_failed note
#d-i netcfg/dhcp_options select Configure network manually
# Static network configuration.
#
# IPv4 example
#d-i netcfg/get_ipaddress string 192.168.1.42
#d-i netcfg/get_netmask string 255.255.255.0
#d-i netcfg/get_gateway string 192.168.1.1
#d-i netcfg/get_nameservers string 192.168.1.1
#d-i netcfg/confirm_static boolean true
#
# IPv6 example
#d-i netcfg/get_ipaddress string fc00::2
#d-i netcfg/get_netmask string ffff:ffff:ffff:ffff::
#d-i netcfg/get_gateway string fc00::1
#d-i netcfg/get_nameservers string fc00::1
#d-i netcfg/confirm_static boolean true
# Any hostname and domain names assigned from dhcp take precedence over
# values set here. However, setting the values still prevents the questions
# from being shown, even if values come from dhcp.
d-i netcfg/get_hostname string unassigned-hostname
d-i netcfg/get_domain string unassigned-domain
# If you want to force a hostname, regardless of what either the DHCP
# server returns or what the reverse DNS entry for the IP is, uncomment
# and adjust the following line.
#d-i netcfg/hostname string somehost
# Disable that annoying WEP key dialog.
d-i netcfg/wireless_wep string
# The wacky dhcp hostname that some ISPs use as a password of sorts.
#d-i netcfg/dhcp_hostname string radish
# If non-free firmware is needed for the network or other hardware, you can
# configure the installer to always try to load it, without prompting. Or
# change to false to disable asking.
d-i hw-detect/load_firmware boolean true
### Network console
# Use the following settings if you wish to make use of the network-console
# component for remote installation over SSH. This only makes sense if you
# intend to perform the remainder of the installation manually.
#d-i anna/choose_modules string network-console
#d-i network-console/authorized_keys_url string http://10.0.0.1/openssh-key
#d-i network-console/password password r00tme
#d-i network-console/password-again password r00tme
# Use this instead if you prefer to use key-based authentication
#d-i network-console/authorized_keys_url http://host/authorized_keys
### Mirror settings
# If you select ftp, the mirror/country string does not need to be set.
#d-i mirror/protocol string ftp
d-i apt-setup/no_mirror boolean true
d-i mirror/country string US
d-i apt-setup/multiverse boolean true
d-i apt-setup/restricted boolean true
d-i apt-setup/universe boolean true
# Alternatively: by default, the installer uses CC.archive.ubuntu.com where
# CC is the ISO-3166-2 code for the selected country. You can preseed this
# so that it does so without asking.
#d-i mirror/http/mirror select CC.archive.ubuntu.com
# Suite to install.
#d-i mirror/suite string xenial
# Suite to use for loading installer components (optional).
#d-i mirror/udeb/suite string xenial
# Components to use for loading installer components (optional).
#d-i mirror/udeb/components multiselect main, restricted
### Account setup
# Skip creation of a root account (normal user account will be able to
# use sudo). The default is false; preseed this to true if you want to set
# a root password.
d-i passwd/root-login boolean true
# Alternatively, to skip creation of a normal user account.
#d-i passwd/make-user boolean false
# Root password, either in clear text
d-i passwd/root-password password MW674656!
d-i passwd/root-password-again password MW674656!
# or encrypted using a crypt(3) hash.
#d-i passwd/root-password-crypted password [crypt(3) hash]
# To create a normal user account.
d-i passwd/user-fullname string mwpos
d-i passwd/username string mwpos
# Normal user's password, either in clear text
d-i passwd/user-password password mw1234
d-i passwd/user-password-again password mw1234
d-i passwd/auto-login boolean true
# or encrypted using a crypt(3) hash.
#d-i passwd/user-password-crypted password [crypt(3) hash]
# Create the first user with the specified UID instead of the default.
#d-i passwd/user-uid string 1010
# The installer will warn about weak passwords. If you are sure you know
# what you're doing and want to override it, uncomment this.
d-i user-setup/allow-password-weak boolean true
# The user account will be added to some standard initial groups. To
# override that, use this.
#d-i passwd/user-default-groups string audio cdrom video
# Set to true if you want to encrypt the first user's home directory.
d-i user-setup/encrypt-home boolean false
### Clock and time zone setup
# Controls whether or not the hardware clock is set to UTC.
d-i clock-setup/utc boolean true
# You may set this to any valid setting for $TZ; see the contents of
# /usr/share/zoneinfo/ for valid values.
d-i time/zone string America/SaoPaulo
# Controls whether to use NTP to set the clock during the install
d-i clock-setup/ntp boolean true
# NTP server to use. The default is almost always fine here.
#d-i clock-setup/ntp-server string ntp.example.com
### Partitioning
# This makes partman automatically partition without confirmation
d-i partman-auto/method string regular
d-i partman-lvm/device_remove_lvm boolean true
d-i partman-md/device_remove_md boolean true
d-i partman-auto/choose_recipe select atomic
d-i partman/confirm boolean true
d-i partman/confirm_write_new_label boolean true
d-i partman-auto/init_automatically_partition select Guided - use entire disk
d-i partman/choose_partition select Finish partitioning and write changes to disk
d-i partman/confirm string boolean true
d-i partman/confirm_nooverwrite string boolean true
# Locale
d-i debian-installer/locale string en_US
d-i console-setup/ask_detect boolean false
d-i console-setup/layoutcode string br
### Base system installation
# Configure a path to the preconfigured base filesystem. This can be used to
# specify a path for the installer to retrieve the filesystem image that will
# be deployed to disk and used as a base system for the installation.
#d-i live-installer/net-image string /install/filesystem.squashfs
# Configure APT to not install recommended packages by default. Use of this
# option can result in an incomplete system and should only be used by very
# experienced users.
#d-i base-installer/install-recommends boolean false
# The kernel image (meta) package to be installed; "none" can be used if no
# kernel is to be installed.
#d-i base-installer/kernel/image string linux-generic
### Apt setup
# You can choose to install restricted and universe software, or to install
# software from the backports repository.
#d-i apt-setup/restricted boolean true
#d-i apt-setup/universe boolean true
#d-i apt-setup/backports boolean true
# Uncomment this if you don't want to use a network mirror.
d-i apt-setup/use_mirror boolean false
# Select which update services to use; define the mirrors to be used.
# Values shown below are the normal defaults.
#d-i apt-setup/services-select multiselect security
#d-i apt-setup/security_host string security.ubuntu.com
#d-i apt-setup/security_path string /ubuntu
# Additional repositories, local[0-9] available
#d-i apt-setup/local0/repository string \
# http://local.server/ubuntu xenial main
#d-i apt-setup/local0/comment string local server
# Enable deb-src lines
#d-i apt-setup/local0/source boolean true
# URL to the public key of the local repository; you must provide a key or
# apt will complain about the unauthenticated repository and so the
# sources.list line will be left commented out
#d-i apt-setup/local0/key string http://local.server/key
# By default the installer requires that repositories be authenticated
# using a known gpg key. This setting can be used to disable that
# authentication. Warning: Insecure, not recommended.
#d-i debian-installer/allow_unauthenticated boolean true
# Uncomment this to add multiarch configuration for i386
#d-i apt-setup/multiarch string i386
### Package selection
#tasksel tasksel/first multiselect xubuntu-desktop
#tasksel tasksel/first multiselect lamp-server, print-server
#tasksel tasksel/first multiselect kubuntu-desktop
# Individual additional packages to install
#d-i pkgsel/include string openssh-server xubuntu-desktop
# Whether to upgrade packages after debootstrap.
# Allowed values: none, safe-upgrade, full-upgrade
d-i pkgsel/upgrade select none
d-i pkgsel/install-language-support boolean false
# Language pack selection
#d-i pkgsel/language-packs multiselect de, en, zh
# Policy for applying updates. May be "none" (no automatic updates),
# "unattended-upgrades" (install security updates automatically), or
# "landscape" (manage system with Landscape).
d-i pkgsel/update-policy select none
# Some versions of the installer can report back on what software you have
# installed, and what software you use. The default is not to report back,
# but sending reports helps the project determine what software is most
# popular and include it on CDs.
#popularity-contest popularity-contest/participate boolean false
# By default, the system's locate database will be updated after the
# installer has finished installing most packages. This may take a while, so
# if you don't want it, you can set this to "false" to turn it off.
#d-i pkgsel/updatedb boolean true
### Boot loader installation
# Grub is the default boot loader (for x86). If you want lilo installed
# instead, uncomment this:
#d-i grub-installer/skip boolean true
# To also skip installing lilo, and install no bootloader, uncomment this
# too:
#d-i lilo-installer/skip boolean true
# This is fairly safe to set, it makes grub install automatically to the MBR
# if no other operating system is detected on the machine.
d-i grub-installer/only_debian boolean true
# This one makes grub-installer install to the MBR if it also finds some other
# OS, which is less safe as it might not be able to boot that other OS.
d-i grub-installer/with_other_os boolean true
# Due notably to potential USB sticks, the location of the MBR can not be
# determined safely in general, so this needs to be specified:
#d-i grub-installer/bootdev string /dev/sda
# To install to the first device (assuming it is not a USB stick):
#d-i grub-installer/bootdev string default
# Alternatively, if you want to install to a location other than the mbr,
# uncomment and edit these lines:
#d-i grub-installer/only_debian boolean false
#d-i grub-installer/with_other_os boolean false
#d-i grub-installer/bootdev string (hd0,1)
# To install grub to multiple disks:
#d-i grub-installer/bootdev string (hd0,1) (hd1,1) (hd2,1)
# Optional password for grub, either in clear text
#d-i grub-installer/password password r00tme
#d-i grub-installer/password-again password r00tme
# or encrypted using an MD5 hash, see grub-md5-crypt(8).
#d-i grub-installer/password-crypted password [MD5 hash]
# Use the following option to add additional boot parameters for the
# installed system (if supported by the bootloader installer).
# Note: options passed to the installer will be added automatically.
#d-i debian-installer/add-kernel-opts string nousb
### Finishing up the installation
# During installations from serial console, the regular virtual consoles
# (VT1-VT6) are normally disabled in /etc/inittab. Uncomment the next
# line to prevent this.
#d-i finish-install/keep-consoles boolean true
# Avoid that last message about the install being complete.
ubiquity finish-install/reboot_in_progress note
ubiquity ubiquity/reboot boolean true
# This will prevent the installer from ejecting the CD during the reboot,
# which is useful in some situations.
#d-i cdrom-detect/eject boolean false
# This is how to make the installer shutdown when finished, but not
# reboot into the installed system.
#d-i debian-installer/exit/halt boolean true
# This will power off the machine instead of just halting it.
#d-i debian-installer/exit/poweroff boolean true
### Preseeding other packages
# Depending on what software you choose to install, or if things go wrong
# during the installation process, it's possible that other questions may
# be asked. You can preseed those too, of course. To get a list of every
# possible question that could be asked during an install, do an
# installation, and then run these commands:
# debconf-get-selections --installer > file
# debconf-get-selections >> file
#### Advanced options
### Running custom commands during the installation
# d-i preseeding is inherently not secure. Nothing in the installer checks
# for attempts at buffer overflows or other exploits of the values of a
# preconfiguration file like this one. Only use preconfiguration files from
# trusted locations! To drive that home, and because it's generally useful,
# here's a way to run any shell command you'd like inside the installer,
# automatically.
# This first command is run as early as possible, just after
# preseeding is read.
#d-i preseed/early_command string anna-install some-udeb
# This command is run immediately before the partitioner starts. It may be
# useful to apply dynamic partitioner preseeding that depends on the state
# of the disks (which may not be visible when preseed/early_command runs).
#d-i partman/early_command \
# string debconf-set partman-auto/disk "$(list-devices disk | head -n1)"
# This command is run just before the install finishes, but when there is
# still a usable /target directory. You can chroot to /target and use it
# directly, or use the apt-install and in-target commands to easily install
# packages and run commands in the target system.
#d-i preseed/late_command string apt-install zsh; in-target chsh -s /bin/zsh
ubiquity ubiquity/success_command string \
echo 'post-install' > /target/home/mwpos/ubiquity_success_command.txt;
Basta adicionar o parâmetro de inicialização do kernel 'noprompt'. Se você estiver usando o Grub, edite boot / grub / grub.cfg.
Automação da Ubiquity
Nota: não se esqueça de adicionar antes do '---'