Hostname split

[root@ve10:Active] config  b rule myrule list
rule myrule {
   when RULE_INIT {
   set hostname "f5.com"
   set last_dot [string last "." $hostname]
   set second_dot [string last "." $hostname [expr {$last_dot -1}]]
   set suffix [string range $hostname [expr {$last_dot + 1}] end]
   set host [string range $hostname [expr {$second_dot + 1}] [expr {$last_dot - 1}]]
   set prefix [string range $hostname 0 [expr {$second_dot - 1}]]
   log local0. "hostname=$hostname | prefix=$prefix | host=$host | suffix=$suffix"

   set hostname "www.f5.com"
   set last_dot [string last "." $hostname]
   set second_dot [string last "." $hostname [expr {$last_dot -1}]]
   set suffix [string range $hostname [expr {$last_dot + 1}] end]
   set host [string range $hostname [expr {$second_dot + 1}] [expr {$last_dot - 1}]]
   set prefix [string range $hostname 0 [expr {$second_dot - 1}]]
   log local0. "hostname=$hostname | prefix=$prefix | host=$host | suffix=$suffix"

   set hostname "xxx.yyy.f5.com"
   set last_dot [string last "." $hostname]
   set second_dot [string last "." $hostname [expr {$last_dot -1}]]
   set suffix [string range $hostname [expr {$last_dot + 1}] end]
   set host [string range $hostname [expr {$second_dot + 1}] [expr {$last_dot - 1}]]
   set prefix [string range $hostname 0 [expr {$second_dot - 1}]]
   log local0. "hostname=$hostname | prefix=$prefix | host=$host | suffix=$suffix"
}
}

[root@ve10:Active] config  tail -f /var/log/ltm
Oct 12 19:25:48 local/ve10 err mcpd[3815]: 01020066:3: The requested rule (myrule) already exists in partition Common.
Oct 12 19:25:48 local/tmm info tmm[7926]: Rule myrule : hostname=f5.com | prefix= | host=f5 | suffix=com
Oct 12 19:25:48 local/tmm info tmm[7926]: Rule myrule : hostname=www.f5.com | prefix=www | host=f5 | suffix=com
Oct 12 19:25:48 local/tmm info tmm[7926]: Rule myrule : hostname=xxx.yyy.f5.com | prefix=xxx.yyy | host=f5 | suffix=com