Get the CPU usage as a percentage. Great for use inside byobu/tmux, but can be used standalone.

5_cpu_percent

#!/bin/bash
#
#    5_cpu_percent: get the global CPU usage as a percentage
#
#    Copyright (C) 2016 Santiago Saavedra
#
#    Authors: Santiago Saavedra <santiagosaavedra@gmail.com>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, version 3 of the License.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.




self=$(basename $0)
mycache="$BYOBU_RUN_DIR/cache.$BYOBU_BACKEND/custom.$self.current"
touch "$mycache"

## By reading and continuing we are changing the value

_nice=x
_sys=
_idle=
_user=
_iowait=
_irq=
_softirq=
_steal=
_guest=
_guest_nice=

get_current_usage () {
	grep 'cpu ' /proc/stat
}

CURRENT_USAGE=$(get_current_usage)


get_cpu_diff () {
	local bogus user nice system idle iowait irq softirq steal guest guest_nice
	read bogus user nice system idle iowait irq softirq steal guest guest_nice <<EOF
$1
EOF

	local prev_idle=$((idle + iowait))
	local prev_nonidle=$((user + nice + system + irq + softirq + steal))
	local prev_total=$((prev_idle + prev_nonidle))

	read bogus user nice system idle iowait irq softirq steal guest guest_nice <<EOF
$2
EOF

	local cur_idle=$((idle + iowait))
	local cur_nonidle=$((user + nice + system + irq + softirq + steal))
	local cur_total=$((cur_idle + cur_nonidle))

	local total_diff=$((cur_total - prev_total))
	local idle_diff=$((cur_idle - prev_idle))

	echo -n ""
	local pct=$(echo "scale=2; ($total_diff - $idle_diff) / $total_diff * 100" | bc)
	echo "$pct%% "

}

next_cpu_bar () {
	echo "$CURRENT_USAGE" > "$mycache"
}

last_cpu_bar () {
	local last=$(< "$mycache")
	local now="$CURRENT_USAGE"
	get_cpu_diff "$last" "$now"
}

last_cpu_bar
next_cpu_bar

# vi: syntax=sh ts=4 noexpandtab