Retrieve links and emailaddresses from some webpage

This script started as a Bash coding exercise but turned out to be a very useful way of getting data from websites, and it contains many useful little coding tricks.

#!/bin/sh

##############################################
NAME_="webextract"
PURPOSE_="extract links and/or email-addresses from a webpage"
SYNOPSIS_="$NAME_ [-e  ] [-l  ] "
OPTIONS_="
   -e     extract all emailaddresses from a url
   -l     extract all links from url
   -h          show help (this)"
REQUIRES_="Curl"
VERSION_="0.9"
PUROSE_=""
#Created by Lx
#licence : GPL3
#################################################

usage () {
echo >&2 "
\033[1m$NAME_ $VERSION_ \033[0m - $PURPOSE_
Usage: $SYNOPSIS_
Options: $OPTIONS_
"
    exit 1
}

# tmp file set up
tmp_1=/tmp/tmp.${RANDOM}$$

# signal trapping and tmp file removal
trap 'rm -f $tmp_1 >/dev/null 2>&1' 0
trap "exit 1" 1 2 3 15

extract () {
 while getopts ":e:l:h:" optname
   do
      case "$optname" in
         "e")
         curl -s -S $OPTARG |{
         tr ',;<>()"\47 ' '[\n*]' | sed -n -e 's/mailto://gI' -e '/@/p'  > $tmp_1
         cat $tmp_1
         }
            ;;
         "l")
         curl -s -S $OPTARG |{
         tr '<>"\47 ' '[\n*]' | sed -n -e 's/href=//gI' -e 's/src=//gI' -e '/http:/Ip' > $tmp_1
         cat $tmp_1
         }
            ;;
         "h")
            usage
            ;;
         "?")
            echo " Unknown option $OPTARG"
            usage
            ;;
         ":")
            usage
            ;;
         *)
         # should not occur
            echo "unknown error"
            ;;
         esac
      done
   return $OPTIND
}

showargs () {
  for p in "$@"
    do
      echo "[$p]"
    done
}

###
if [ $# != 0 ]; then
   extract  $@
else
   usage
fi