例1：
[root@nhserver2 ~]# cat nagios.txt
<TD ALIGN=LEFT valign=center CLASS='statusBGCRITICAL'><A HREF='extinfo.cgi?type=2&host=192.168.5.110&service=SSH'>SSH</A></TD></TR>
<TD ALIGN=LEFT valign=center CLASS='statusBGCRITICAL'><A HREF='extinfo.cgi?type=2&host=192.168.5.110&service=check-host-alive'>check-host-alive</A></TD></TR>
[root@nhserver2 ~]# sed -e 's/([0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3})/1555/g' nagios.txt
<TD ALIGN=LEFT valign=center CLASS='statusBGCRITICAL'><A HREF='extinfo.cgi?type=2&host=192.168.5.110555&service=SSH'>SSH</A></TD></TR>
<TD ALIGN=LEFT valign=center CLASS='statusBGCRITICAL'><A HREF='extinfo.cgi?type=2&host=192.168.5.110555&service=check-host-alive'>check-host-alive</A></TD></TR>