Please start making sense. The link you posted for rehash goes to a page which states:

Sorry, no data found for `rehash'.

I'm sorry. Perhaps using links to man pages [man://man] shouldn't be used anymore. rehash is part of (t)csh. While I could have checked the link PerlMonks uses for man pages. I think it's fair to say that you are out of line on this. Because when I type man rehash in my terminal/console, I receive

BUILTIN(1)              FreeBSD General Commands Manual             BU
+ILTIN(1)

NAME
     builtin, !, %, ., :, @, [, {, }, alias, alloc, bg, bind, bindkey,
+ break,
     breaksw, builtins, case, cd, chdir, command, complete, continue, 
+default,
     dirs, do, done, echo, echotc, elif, else, end, endif, endsw, esac
+, eval,
     exec, exit, export, false, fc, fg, filetest, fi, for, foreach, ge
+topts,
     glob, goto, hash, hashstat, history, hup, if, jobid, jobs, kill, 
+limit,
     local, log, login, logout, ls-F, nice, nohup, notify, onintr, pop
+d,
     printenv, pushd, pwd, read, readonly, rehash, repeat, return, sch
+ed, set,
     setenv, settc, setty, setvar, shift, source, stop, suspend, switc
+h,
     telltc, test, then, time, times, trap, true, type, ulimit, umask,
     unalias, uncomplete, unhash, unlimit, unset, unsetenv, until, wai
+t,
     where, which, while -- shell built-in commands

SYNOPSIS
     See the built-in command description in the appropriate shell man
+ual
     page.

DESCRIPTION
     Shell builtin commands are commands that can be executed within t
+he run-
     ning shell's process.  Note that, in the case of csh(1) builtin c
+ommands,
     the command is executed in a subshell if it occurs as any compone
+nt of a
     pipeline except the last.

     If a command specified to the shell contains a slash `/', the she
+ll will
     not execute a builtin command, even if the last component of the 
+speci-
     fied command matches the name of a builtin command.  Thus, while 
+specify-
     ing ``echo'' causes a builtin command to be executed under shells
+ that
     support the echo builtin command, specifying ``/bin/echo'' or ``.
+/echo''
     does not.

     While some builtin commands may exist in more than one shell, the
+ir oper-
     ation may be different under each shell which supports them.  Bel
+ow is a
     table which lists shell builtin commands, the standard shells tha
+t sup-
     port them and whether they exist as standalone utilities.

     Only builtin commands for the csh(1) and sh(1) shells are listed 
+here.
     Consult a shell's manual page for details on the operation its bu
+iltin
     commands.  Beware that the sh(1) manual page, at least, calls som
+e of
     these commands ``built-in commands'' and some of them ``reserved 
+words''.
     Users of other shells may need to consult an info(1) page or othe
+r
     sources of documentation.

     Commands marked ``No**'' under External do exist externally, but 
+are
     implemented as scripts using a builtin command of the same name.

           Command       External    csh(1)    sh(1)
           !             No          No        Yes
           %             No          Yes       No
           .             No          No        Yes
           :             No          Yes       Yes
           @             No          Yes       No
           [             Yes         No        Yes
           {             No          No        Yes
           }             No          No        Yes
 ...
[download]

So kindly point your -- more justly.

--Chris

#!/usr/bin/perl -Tw
use Perl::Always or die;
my $perl_version = (5.12.5);
print $perl_version;