#!/bin/bash

# From /sbin/start_udev by Greg KH (GPL v2 only)
# Does $1 contain $2 ?
strstr() {
  [ "${1#*$2*}" = "$1" ] && return 1
  return 0
}

NEEDLE=hello
HAYSTACK=helloworld

strstr $HAYSTACK $NEEDLE && echo "$HAYSTACK contains $NEEDLE" || \
     echo "$HAYSTACK does not contain $NEEDLE"
# "helloworld" does contain "hello"

NEEDLE=goodbye
strstr $HAYSTACK $NEEDLE && echo "$HAYSTACK contains $NEEDLE" || \
     echo "$HAYSTACK does not contain $NEEDLE"
# "helloworld" doesn't contain "goodbye"