/usr/share/bash-completion/completions/taskset is in util-linux 2.27.1-6ubuntu3.
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  | _taskset_module()
{
	local cur prev OPTS
	COMPREPLY=()
	cur="${COMP_WORDS[COMP_CWORD]}"
	prev="${COMP_WORDS[COMP_CWORD-1]}"
	case $prev in
		'-c'|'--cpu-list')
			local prefix realcur CPULIST_ALL CPULIST
			realcur="${cur##*,}"
			prefix="${cur%$realcur}"
			CPULIST_ALL=$(sed 's/^/{/; s/-/../g; s/,/} {/g; s/$/}/' /sys/devices/system/cpu/online)
			for WORD in $(eval echo $CPULIST_ALL); do
				if ! [[ $prefix == *"$WORD"* ]]; then
					CPULIST="$WORD $CPULIST"
				fi
			done
			compopt -o nospace
			COMPREPLY=( $(compgen -P "$prefix" -W "$CPULIST" -S ',' -- $realcur) )
			return 0
			;;
		'-p'|'--pid')
			local PIDS
			# FIXME: the pid argument is ambiguous.  When
			# setting an affinity the optarg has to be cpu
			# mask.  The following is good only for getting
			# affinity.
			PIDS=$(for I in /proc/[0-9]*; do echo ${I##"/proc/"}; done)
			COMPREPLY=( $(compgen -W "$PIDS" -- $cur) )
			return 0
			;;
		'-h'|'--help'|'-V'|'--version')
			return 0
			;;
	esac
	case $cur in
		-*)
			OPTS="--all-tasks --pid --cpu-list --help --version"
			COMPREPLY=( $(compgen -W "${OPTS[*]}" -- $cur) )
			return 0
			;;
	esac
	compopt -o bashdefault
	COMPREPLY=( $(compgen -c -- $cur) )
	return 0
}
complete -F _taskset_module taskset
 |