use strict;
open (JE, "< c:\\tuls\\tuls.txt") || die "Can not open the file ";

my $ou;
while (<JE>)
{
	$_=~s/findtext/changetext/g;
	$ou.=$_;
}

close(JE);
open (JE, "> c:\\tuls\\tuls.txt") ;
print JE $ou;
close (JE);