Change file or directory flags.

# To set the 'hidden' flag for a file:
chflags <hidden> <path/to/file>

# To unset the 'hidden' flag for a file:
chflags <hidden> <path/to/file>

# To recursively set the 'uchg' flag for a directory:
chflags -R <uchg> <path/to/directory>

# To recursively unset the 'uchg' flag for a directory:
chflags -R <nouchg> <path/to/directory>