- new program: `[' (much like `test')
** New features
+- chown no longer tries to preserve set-user-ID and set-group-ID bits;
+ on some systems, the chown syscall resets those bits, and previous
+ versions of the chown command would call chmod to restore the original,
+ pre-chown(2) settings, but that behavior is problematic.
+ 1) There was a window whereby a malicious user, M, could subvert a
+ chown command run by some other user and operating on files in a
+ directory where M has write access.
+ 2) Before (and even now, on systems with chown(2) that doesn't reset
+ those bits), an unwary admin. could use chown unwittingly to create e.g.,
+ a set-user-ID root copy of /bin/sh.
- head now accepts --lines=-N (--bytes=-N) to print all but the
N lines (bytes) at the end of the file
- md5sum --check now accepts the output of the BSD md5sum program, e.g.,