`@mej` requested that Charliecloud add the UTS namespace so that containers can have a different hostname from the host (i.e., `gethostname(2)`). The use case this supports would be building RPMs with a specified hostname. The approach I had in mind would be to (1) unconditionally use `CLONE_UTS` and (2) add a command line option `--hostname=foo` that uses `sethostname(2)` to set the hostname to `foo`. I'm looking for comments on whether this is a good idea and any additional use cases.