IOSTAT script for ZFS tests

#!/bin/sh
#
# Display most relevant iostat bandwidth/latency numbers.  The output is
# dependent on the name of the script/symlink used to call it.
#
helpstr="
iostat:         Show iostat values since boot (summary page).
iostat-1s:      Do a single 1-second iostat sample and show values.
iostat-10s:     Do a single 10-second iostat sample and show values."
script="${0##*/}"
if [ "$1" = "-h" ] ; then
    echo "$helpstr" | grep "$script:" | tr -s '\t' | cut -f 2-
    exit
fi
if [ "$script" = "iostat-1s" ] ; then
    # Do a single one-second sample
    interval=1
    # Don't show summary stats
    brief="yes"
elif [ "$script" = "iostat-10s" ] ; then
    # Do a single ten-second sample
    interval=10
    # Don't show summary stats
    brief="yes"
fi
if [ -f "$VDEV_UPATH" ] ; then
    # We're a file-based vdev, iostat doesn't work on us.  Do nothing.
    exit
fi
out=$(iostat -x "${VDEV_UPATH##*/}" \
    ${interval:+"$interval"} \
    ${interval:+"1"} | tail -n 2)
     
# Sample output (we want the last two lines):
#  
# Linux 2.6.32-642.13.1.el6.x86_64 (centos68)   03/09/2017      _x86_64_        (6 CPU)
#
# avg-cpu:  %user   %nice %system %iowait  %steal   %idle
#           0.00    0.00    0.00    0.00    0.00  100.00
#
# Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
# sdb               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
#
# Get the column names
cols=$(echo "$out" | head -n 1)
# Get the values and tab separate them to make them cut-able.
vals=$(echo "$out" | tail -n 1 | tr -s '[:space:]' '\t')
i=0
for col in $cols ; do
    i=$((i+1))
    # Skip the first column since it's just the device name
    if [ $i -eq 1 ]; then
        continue
    fi
    # Get i'th value
    val=$(echo "$vals" | cut -f "$i")
    echo "$col=$val"
done