/usr/share/initramfs-tools/scripts/casper-functions is in casper 1.340.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51  | . /scripts/functions
# Print a message and wait for enter
log_wait_msg()
{
	if [ -x /bin/plymouth ] && plymouth --ping; then
		plymouth message --text="$@"
		plymouth watch-keystroke | read nunya
	fi
	_log_msg "Waiting: $@ ..."
}
lang2locale() {
	langpart="${1%%_*}"
	if [ "$1" != "C" ]; then
		# Match the language code with 1st field in languagelist
		line=$(grep -v "^#" /root/usr/share/localechooser/languagelist | cut -f1,3,5 -d\; | grep -v ';C$' | grep "^$langpart[_;]")
		if [ -n "$line" ]; then
			if [ "$(echo "$line" | grep -c '')" -gt 1 ]; then
				# More than one match; try matching the
				# country as well.
				countrypart="${1#*_}"
				if [ "$countrypart" = "$1" ]; then
					countryline="$(echo "$line" | head -n1)"
					echo "${countryline##*;}"
					return
				fi
				countrypart="${countrypart%%[@.]*}"
				countryline="$(echo "$line" | grep ";$countrypart;" | head -n1 || true)"
				if [ "$countryline" ]; then
					echo "${countryline##*;}"
					return
				fi
			fi
			echo "${line##*;}"
		fi
	else
		echo "C"
	fi
}
load_confmodule() {
	# Only do this once.
	if [ -z "$DEBCONF_REDIR" ]; then
		exec <&4
		export DEBIAN_HAS_FRONTEND=1
		export DEBCONF_REDIR=1
	fi
	. /root/usr/share/debconf/confmodule
}
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