execute a command as another user

change the file ownership

-R     Recursively  change  file  user and group IDs. For each file operand that names a directory, chown
       shall change the user ID (and group ID, if specified) of the directory and all files in  the  file
       hierarchy  below  it. Unless a -H, -L, or -P option is specified, it is unspecified which of these
       options will be used as the default.

-L     If  the  -R  option  is  specified  and  a  symbolic  link referencing a file of type directory is
       specified on the command line or encountered during the traversal of a file hierarchy, chown shall
       change  the  user ID (and group ID, if specified) of the directory referenced by the symbolic link
       and all files in the file hierarchy below it.