我已经启用了 copr 存储库：
dnf copr enable jonludlam/opam
当我尝试安装时dnf -v -y install opam，很明显我正在搜索不存在的 dnf repo：
cachedir: /var/cache/dnf
Loaded plugins: playground, reposync, config-manager, download, builddep, noroot, debuginfo-install, Query, protected_packages, needs-restarting, generate_completion_cache, copr
DNF version: 1.1.10
repo: using cache for: rpmfusion-free
not found deltainfo for: RPM Fusion for Fedora 25 - Free
not found updateinfo for: RPM Fusion for Fedora 25 - Free
Cannot download 'https://copr-be.cloud.fedoraproject.org/results/jonludlam/opam/fedora-25-x86_64/': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried.
repo: using cache for: epel
not found deltainfo for: Extra Packages for Enterprise Linux 7 - x86_64
repo: using cache for: updates
repo: using cache for: rpmfusion-free-updates
not found deltainfo for: RPM Fusion for Fedora 25 - Free - Updates
not found updateinfo for: RPM Fusion for Fedora 25 - Free - Updates
repo: using cache for: fedora
not found updateinfo for: Fedora 25 - x86_64
Cannot download 'https://copr-be.cloud.fedoraproject.org/results/sergiomb/google-drive-ocamlfuse/fedora-25-x86_64/': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried.
Failed to synchronize cache for repo 'jonludlam-opam', disabling.
Failed to synchronize cache for repo 'sergiomb-google-drive-ocamlfuse', disabling.
rpmfusion-free: using metadata from Fri Nov 18 18:41:21 2016.
epel: using metadata from Wed Nov 30 02:44:26 2016.
updates: using metadata from Tue Nov 29 23:47:49 2016.
rpmfusion-free-updates: using metadata from Mon Nov 28 03:10:31 2016.
fedora: using metadata from Thu Nov 17 05:09:01 2016.
Last metadata expiration check: 1:02:29 ago on Wed Nov 30 14:25:15 2016.
No package opam available.
Error: Unable to find a match.
鉴于我使用的是 Fedora 25，但列出的软件包仅适用于 Fedora 24 及以上版本（https://copr-be.cloud.fedoraproject.org/results/jonludlam/opam/那么，是否可以强制 dnf 使用任何特定版本？
谢谢，
马特
答案1
COPR repo 已经有一段时间没有更新了，因此软件包没有为你的 Fedora 版本构建。有几种可能的情况：
- 要求 repo 所有者为 Fedora 25 重建软件包（首选）
- 修改
/etc/yum.repos.d/_copr_jonludlam-opam.repo并将 替换为$releasever。23这将安装最新构建的软件包 - 分叉项目并为 Fedora 25 自行重建软件包（如果您有 FAS 帐户）