[R] Escaping . in regular expression

[Prof. John C Nash]

If I run


cvec<-c("test.f", "test.sf", "try.g","try.res", "try.f")
print(cvec)
indx<-grep('\.f',cvec,perl=TRUE)
fset<-cvec[indx]
print(fset)

I get

 > cvec<-c("test.f", "test.sf", "try.g","try.res", "try.f")
 > print(cvec)
[1] "test.f"  "test.sf" "try.g"   "try.res" "try.f"
 > indx<-grep("\.f",cvec,perl=TRUE)
Warning messages:
1: '\.' is an unrecognized escape in a character string
2: unrecognized escape removed from "\.f"
 > fset<-cvec[indx]
 > print(fset)
[1] "test.f"  "test.sf" "try.f"
 >

This ignores the . for which I want to test.

In perl, the function

#!/usr/bin/perl
use strict;
my @cvec=("test.f", "test.sf", "try.g","try.res", "try.f");
foreach my $elem (@cvec) {
    print "$elem : ";
    if ( $elem =~ '\.f' ) {
        print "matches \n";
    } else {
        print "does not match \n";
    }
}


gives

$ perl perlmatch.pl
test.f : matches
test.sf : does not match
try.g : does not match
try.res : does not match
try.f : matches
$

which does what I want. It looks like a bug (or at least a nasty 
documentation failure) of "perl=TRUE".

Anyone have suggestions of how to get appropriate filtering? I need this 
to automate optimization tests on large sets of test problems.

Cheers, JN