sed has been upgraded to release 4.2.1. When used without the "-i" option, the only effect of the upgrade will be improved performance and bug fixes. However, the release introduces the following visible changes to the behavior of "sed -i":
* "sed -i" will always preserve the permissions, ACLs and security context of the original file, as long as the user can set them (for example, when a file is owned by root, a user will not be able to preserve ownership of the file after "sed -i").
Up until Red Hat Enterprise Linux 5.4, "sed -i" had a different behavior: it will never try to preserve ownership if the "-c" ("--copy") option was not given on the commandline; and it would always preserve the existing owner if the "-c" ("--copy") option was given.
The new behavior is consistent with the existing documentation of "sed", with other Linux distributions, as well as with implementations of "sed" on other operating systems.
The new release also fixes a minor security issue with "sed -i". The output of "sed -i" is now kept inaccessible to other users until it is complete.