哪个包负责 Ubuntu 上 systemd/systemctl 的 bash 补全？

Question

我本地安装了 Ubuntu 16.04，默认情况下它具有systemctl子命令的 bash 补全功能。但是当我在 Digital Ocean 上启动 Ubuntu Server 18.04 实例时，子systemctl命令没有 bash 补全。我预计会缺少一些软件包，例如systemd-completion，但在我本地的 Ubuntu 上我只安装了这些软件包：

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ii  libpam-systemd:amd64                          229-4ubuntu21.2                                          amd64        system and service manager - PAM module\nii  libsystemd0:amd64                             229-4ubuntu21.2                                          amd64        systemd utility library\nii  libsystemd0:i386                              229-4ubuntu21.2                                          i386         systemd utility library\nii  systemd                                       229-4ubuntu21.2                                          amd64        system and service manager\nii  systemd-shim                                  9-1bzr4ubuntu1                                           amd64        shim for systemd\nii  systemd-sysv                                  229-4ubuntu21.2                                          amd64        system and service manager - SysV links\n

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和竣工工程。这bash-completion软件包已安装在两台机器上。

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另外，在/etc/bash_completion.d/我的本地 16.04 机器上，我没有看到任何相关的 systemctl 完成文件

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-rw-r--r--   1 root root   408 \xd1\x81\xd0\xb5\xd1\x80 21  2015 cryptdisks\n-rw-r--r--   1 root root   323 \xd0\xb1\xd0\xb5\xd1\x80 18  2016 desktop-file-validate\n-rw-r--r--   1 root root  2384 \xd1\x81\xd0\xb5\xd1\x80 13  2010 dkms\n-rw-r--r--   1 root root   439 \xd1\x81\xd0\xb5\xd1\x80 11  2017 git-prompt\n-rw-r--r--   1 root root 11144 \xd1\x82\xd1\x80\xd0\xb0 11  2017 grub\n-rw-r--r--   1 root root   736 \xd1\x82\xd1\x80\xd0\xb0  7  2013 insserv\n-rw-r--r--   1 root root  6596 \xd0\xbb\xd1\x8e\xd1\x82 19 23:06 libreoffice.sh\n-rw-r--r--   1 root root   553 \xd0\xbb\xd1\x8e\xd1\x82  2  2016 openvpn\n

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那么，我应该安装什么包才能完成systemctl子命令的 bash？\n也许我应该在 bash 配置中的某处打开某些功能？

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Answer 1

我首先找到了这个答案，找出哪个包提供了systemctl：

$ dpkg -S $(type -p systemctl)
systemd: /bin/systemctl

然后查看systemd包装内的内容，我发现：

$ dpkg -L systemd
...<snip>...
/usr/share/bash-completion
/usr/share/bash-completion/completions
/usr/share/bash-completion/completions/systemd-run
/usr/share/bash-completion/completions/timedatectl
/usr/share/bash-completion/completions/systemd-analyze
/usr/share/bash-completion/completions/systemd-cgtop
/usr/share/bash-completion/completions/systemd-delta
/usr/share/bash-completion/completions/systemd-path
/usr/share/bash-completion/completions/journalctl
/usr/share/bash-completion/completions/systemd-detect-virt
/usr/share/bash-completion/completions/localectl
/usr/share/bash-completion/completions/networkctl
/usr/share/bash-completion/completions/hostnamectl
/usr/share/bash-completion/completions/bootctl
/usr/share/bash-completion/completions/systemd-cat
/usr/share/bash-completion/completions/systemd-cgls
/usr/share/bash-completion/completions/systemctl       <---
/usr/share/bash-completion/completions/busctl
/usr/share/bash-completion/completions/loginctl