and compare these values between when run from the command line vs. when run as a web script. If they are different, then "/" is different in the two environment because one (probably the web server) is chrooted as a security measure.
print join( ":", (stat("/"))[0,1] ), $/;
If this is the problem, then you'll have to copy the file to someplace under the web server's virtual root.
BTW, `ls -ali /` is probably more what the original suggestion should have been.
(but my friends call me "Tye")