FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/cmd/zpool/zpool.d/iostat-1s

     #!/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
    
    # Sometimes, UPATH ends up /dev/(null).
    # That should be corrected, but for now...
    # shellcheck disable=SC2154
    if [ ! -b "$VDEV_UPATH" ]; then
            somepath="${VDEV_PATH}"
    else
            somepath="${VDEV_UPATH}"
    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 "$somepath" ] ; then
            # We're a file-based vdev, iostat doesn't work on us.  Do nothing.
            exit
    fi
    
    if [ "$(uname)" = "FreeBSD" ]; then
            out=$(iostat -dKx \
                    ${interval:+"-w $interval"} \
                    ${interval:+"-c 1"} \
                    "$somepath" | tail -n 2)
    else
            out=$(iostat -kx \
                    ${brief:+"-y"} \
                    ${interval:+"$interval"} \
                    ${interval:+"1"} \
                    "$somepath" | grep -v '^$' | tail -n 2)
    fi
    
    
    # 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

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