ACLs are enabled by default in Solaris 2.9

... and probably earlier. This says ACLs were "integrated" into 2.5 back in 1995, which might explain why they're finicky in 2.9. Anyway, I don't want to look this up again and won't believe myself next time it matters, so here I am using ACLs in / on 2.9, where I wouldn't have enabled them on purpose.

buzz> cd /
buzz> touch foo
buzz> setfacl -r -m u:karen:rwx foo
buzz> su karen
buzz> id
uid=1234(karen) gid=200(staff)
buzz> ls -l foo
-rw-r--r--+  1 root     other          0 Apr 30 11:35 foo
buzz> echo "bar" > foo
buzz> ls -l foo
-rw-r--r--+  1 root     other          4 Apr 30 11:36 foo

Here's an entry from a similar blog describing getfacl/setfacl usage on Solaris. Red Hat usage is similar, except: # There's no -r flag, because recalculation is implicit # Partial default ACLs are allowed. (You can set a default user, for example, without having to set defaults for group, other and mask.)