要安装OPAM（已安装ocaml），我遵循了本指南：https://github.com/realworldocaml/book/wiki/Installation-Instructions。以下是我安装OPAM的步骤
$ sudo add-apt-repository ppa:avsm/ppa
$ sudo apt-get update
$ sudo apt-get install curl build-essential m4 ocaml opam
$ opam init (and choose yes)
$ eval `opam config env`
$ opam switch 4.02.3
每当我尝试安装任何软件包（如utop）时，都会收到此错误：
Fatal error:
# opam-version 1.2.2
# os linux
Cannot remove /home/leonard/.opam/archives/camomile.0.8.5+opam.tar.gz (# opam-version 1.2.2
# os linux
opam: "unlink" failed on /home/leonard/.opam/archives/camomile.0.8.5+opam.tar.gz: Permission denied).
关于我做错了什么想法？