I am running the following command but not all files that I know have this string are being returned and I cannot work out why. Specifically the apache log files which are under this path are not being returned.
grep -rl "eval(base64_decode('" /var/www | xargs ls -l
Can anyone point me to what I need to change to get these files returned too?

$ sudo grep -rl "eval(base64_decode('" /var/www | xargs ls -l -rw-r--r-- 1 root root 28 Dec 28 00:01 /var/www/drupal/themes/garland/deletethis1.txt -rw-r--r-- 1 root root 34 Dec 28 00:00 /var/www/drupal/themes/garland/deletethis.txt– devav2 Dec 27 '12 at 19:13