"tracing" version of readlink(1)

I would like a ver开发者_运维技巧sion of "readlink -f" that provides a trace of every individual symlink resolution it performs. Something like:

$ linktrace /usr/lib64/sendmail
/usr/lib64 -> lib
/usr/lib/sendmail -> ../sbin/sendmail
/usr/sbin/sendmail
$ 

I know I have used this utility in the past, on linux, and also remember at the time thinking "the name of this tool is completely unintuitive and I will forget it". Well, that day has arrived.

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NOBODY WINS. The correct answer is "namei".

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This Serverfault answer (in Bash) may be helpful (although it does not claim to be handling all edge cases).

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Code golf anyone?

#!/usr/bin/perl

use File::Spec;
my $g;
my $f = shift;
while (1) {
    print $f;
    $g = readlink($f);
    last unless defined $g;
    printf " -> %s\n", $g;
    $f =~ s,/[^/]*$,,;
    $f = File::Spec->rel2abs($g, $f);
}
print "\n";

Ok, how about this:

#!/usr/bin/perl

use File::Spec;

sub r {
    my ($p, $s) = @_;
    my $l = readlink $p;
    if ($l) {
        printf "%s -> %s\n", $p, $l;
        $p =~ s,/[^/]*$,,;
        r("",File::Spec->rel2abs($l,$p) . $s)
    } else {
        $s =~ s!^(/?[^/]+)(.*)! r($p.$1, $2) !e;
    }
}
r("",shift);

The output is not quite as described but it's understandable. And dig that craaazy recursive executable regexp substitution!