/lib/partman/update.d/60swap is in ubiquity 18.04.14.
This file is owned by root:root, with mode 0o755.
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 | #!/bin/sh
. /lib/partman/lib/base.sh
dev=$1
num=$2
id=$3
size=$4
type=$5
fs=$6
path=$7
name=$8
cd $dev
[ -f $id/method ] || exit 0
method=$(cat $id/method)
if [ "$method" = swap ]; then
RET=''
db_metaget partman/filesystem_short/linux-swap description || RET=''
printf "${RET:-swap}" >$id/visual_filesystem
printf "${RET:-swap}" >$id/visual_mountpoint
open_dialog CHANGE_FILE_SYSTEM $id linux-swap
close_dialog
fi
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