Run a command repeatedly and write the runtimes to a file

bench.sh

#!/bin/bash
n=1000
args=`getopt n:o: $*` || {
 echo "Usage: bench [-n runs] [-o outfile] cmd args ..."
 exit 2
}
set -- $args
for i
do case "$1" in
    -n) n="$2";   shift; shift;;
    -o) out="$2"; shift; shift;;
    --) shift; break;;
   esac
done

TIMEFORMAT=%R
[ -z "$out" ] && out="$1".bench
for ((i=0; i<n; i++))
do #echo $i
   ( time "$@" > /dev/null ) 2>>$out
done