シェルスクリプトでの列フィールド取得方法の実行速度の比較（http://myfuturesightforpast.blogspot.jp/2016/07/how-to-extract-column-field-in-shell.html）

loop-time.sh

#!/bin/sh
# \file      loop-time.sh
# \author    SENOO, Ken
# \copyright CC0

set -u
DATA="loop-data.dat"
: > $DATA
for i in $(seq 1 50000)
do
	echo "1,2,3,4,5,6,7,8,9,0" >> $DATA
done

timeit_loop(){
	start=$(date +%s)
	cat $DATA |
	(
		while read -r line
		do
			last_field="$(eval $1)"
		done
		end=$(date +%s)
		dt=$((end - start))
		echo "time: $dt [s], last field: ${last_field},  $1"
	)
}

LASTCOL=$(($(head -n 1 $DATA | grep -o ',' | wc -l) + 1))

timeit_loop 'echo "$line" | rev | cut -d ',' -f 1 | rev'
timeit_loop 'echo "$line" | cut -d ',' -f $LASTCOL'
timeit_loop 'echo "$line" | awk -F "," "{print \$NF}"'
timeit_loop 'echo "$line" | grep -o  [^,]*$'
timeit_loop 'echo "$line" | sed "s/^.*,\([^,]*\)$/\1/"'
timeit_loop 'echo ${line##*,}'