For exercise - I removed execute permission for others from /bin/pwd:
$ chmod o-x /bin/pwd $ ls -l /bin/pwd -rwxr--r-- 1 root root 26568 Apr 28 2010 /bin/pwd
and as logged as matt I cannot execute /bin/pwd as expected:
$ /bin/pwd $ -bash: /bin/pwd: Permission denied
but sudden it can be executed if not absolute:
$ pwd /home/matt
Why? Thank you!