infinit-loop-check for specified USB device for linux - equivalent to `lsusb | grep KEYWORD`

chkusb.sh

#!/bin/sh

if [ $# -ne 1 ]; then
    echo "Usage: chkusb.sh STRING"
    exit
fi

while [ 1 ]; do
    ret=`lsusb | grep "$1"`
    if [ -z "$ret" ]; then
        ret="Not found: $1"
    fi
    echo `date +"%N "`$ret
done