Shall高级编程

				#!/bin/bash				# ex18.sh								# Does a 'whois domain-name' lookup on any of 3 alternate servers:				#                    ripe.net, cw.net, radb.net								# Place this script -- renamed 'wh' -- in /usr/local/bin								# Requires symbolic links:				# ln -s /usr/local/bin/wh /usr/local/bin/wh-ripe				# ln -s /usr/local/bin/wh /usr/local/bin/wh-cw				# ln -s /usr/local/bin/wh /usr/local/bin/wh-radb								E_NOARGS=65												if [ -z "$1" ]				then				  echo "Usage: `basename $0` [domain-name]"				  exit $E_NOARGS				fi								# Check script name and call proper server.				case `basename $0` in    # Or:    case ${0##*/} in				    "wh"     ) whois $1@whois.ripe.net;;				    "wh-ripe") whois $1@whois.ripe.net;;				    "wh-radb") whois $1@whois.radb.net;;				    "wh-cw"  ) whois $1@whois.cw.net;;				    *        ) echo "Usage: `basename $0` [domain-name]";;				esac 								exit $?