I'm afraid I do not understand your problem. If I take ikegami's code and modify it slightly so as not to depend on the existence of "apache.txt":

while (<DATA>) {
    s/\bis\b/are/g;
    print;
}

__DATA__
Apache is a modular server. This implies that only the most basic func
+tionality
is included in the core server. is it so ?
Extended features are available through modules which can be loaded in
+to Apache.
 By default, a base set of modules is
included in the server at compile-time. If the server is compiled to u
+se dynamic
ally loaded modules, then modules can be
compiled separately and added at any time using the LoadModule directi
+ve. Otherw
ise, Apache must be recompiled to add or
remove modules. Configuration directives may be included conditional o
+n a presen
ce of a particular module by enclosing
them in an <IfModule> block.

[download]

I get the following output (where clearly "is" has been replaced by "are" throughout):

Apache are a modular server. This implies that only the most basic fun
+ctionality

are included in the core server. are it so ?
Extended features are available through modules which can be loaded in
+to Apache.

 By default, a base set of modules are
included in the server at compile-time. If the server are compiled to 
+use dynami
c
ally loaded modules, then modules can be
compiled separately and added at any time using the LoadModule directi
+ve. Otherw

ise, Apache must be recompiled to add or
remove modules. Configuration directives may be included conditional o
+n a presen

ce of a particular module by enclosing
them in an <IfModule> block.

[download]

How does this differ from your desired output?

HTH,

planetscape

In reply to Re^3: regex is not producing desired output by planetscape
in thread regex is not producing desired output by manishrathi

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