According to the following Perl command

( this command part of ksh script )

I can replaced old hostnames with new hostnames in Linux or Solaris

 previos_machine_name=linux1a
 new_machine_name=Red_Hat_linux1a

 export previos_machine_name
 export new_machine_name

.

      perl -i -pe 'next if /^ *#/; s/(\b|[[:^alnum:]])$ENV{previos_machine_name}(\b|[[:^alnum:]])/$1$ENV{new_machine_name}$2/g'  file

EXPLAIN: according to perl command - we not replaces hostnames on the follwoing case:

RULE: [NUMBERS]||[letter]HOSTNAME[NUMBERS]||[letter]

my question

after I used the Perl command in order to replace all old hostnames with new hostnames based on the "RULE" in the Perl command

how to verify that the old hostnames not exist in file ?

for example

   previos_machine_name=linux1a

   new_machine_name=Red_Hat_linux1a

   more file

   AAARed_Hat_linux1a          verification should be ignore from this line
   @Red_Hat_linux1a$             verification should be match this line
   P=Red_Hat_linux1a            verification should be match this line
   XXXRed_Hat_linux1aZZZ         verification should be ignore from this line
   .
   .
   .
   .