如何找出 debconf-set-selections 的变量名称？

Question

假设我想mysql从脚本安装，而不会被问到任何配置问题，比如我想设置什么 root 密码apt。然后我会预设debconf变量：

echo mysql-server-5.5 mysql-server/root_password password xyzzy | debconf-set-selections
echo mysql-server-5.5 mysql-server/root_password_again password xyzzy | debconf-set-selections

我从教程中得到了这个。我不清楚的是：这家伙是如何找出变量名称的？他怎么知道他必须分别设置mysql-server-5.5 mysql-server/root_password password和mysql-server-5.5 mysql-server/root_password_again？

我知道我可以.deb通过发出来提取包dpkg-deb -R package.deb EXTRACTDIR/- 但我没有看到这些变量的存储位置。

我如何找出debconf任何其他包的变量？

Answer 1

您可以使用获取特定安装包的变量debconf-show packagename

前任。

$ sudo debconf-show mysql-server-5.7
* mysql-server/root_password: (password omitted)
* mysql-server/root_password_again: (password omitted)
  mysql-server-5.7/start_on_boot: true
  mysql-server/no_upgrade_when_using_ndb:
  mysql-server/password_mismatch:
  mysql-server-5.7/really_downgrade: false
  mysql-server-5.7/nis_warning:
  mysql-server-5.7/postrm_remove_databases: false
  mysql-server-5.7/installation_freeze_mode_active:

您可以使用 获取数据库中具有变量的所有已安装软件包的列表debconf-show --listowners，因此如果您不确定软件包名称是什么，您可以执行类似的操作

# debconf-show --listowners | grep mysql | xargs debconf-show
* mysql-server/root_password: (password omitted)
* mysql-server/root_password_again: (password omitted)
  mysql-server-5.7/postrm_remove_databases: false
  mysql-server-5.7/nis_warning:
  mysql-server-5.7/installation_freeze_mode_active:
  mysql-server/password_mismatch:
  mysql-server-5.7/start_on_boot: true
  mysql-server/no_upgrade_when_using_ndb:
  mysql-server-5.7/really_downgrade: false

Answer 2

debconf您可以检查使用中存储的内容debconf-get-selections。如果您实际上已经完成安装，这将很有用。

或者，这些设置在包维护者脚本中使用。使用dpkg-deb您运行的命令，它们位于DEBIAN的子目录中EXTRACTDIR。

举个例子，来自lightdm：

$ grep db_ lightdm/DEBIAN -R
lightdm/DEBIAN/postrm:  db_purge
lightdm/DEBIAN/prerm:    db_unregister shared/default-x-display-manager
lightdm/DEBIAN/prerm:    if db_get shared/default-x-display-manager; then
lightdm/DEBIAN/prerm:      db_metaget shared/default-x-display-manager owners
lightdm/DEBIAN/prerm:      db_subst shared/default-x-display-manager choices "$RET"
lightdm/DEBIAN/prerm:      db_get shared/default-x-display-manager
lightdm/DEBIAN/prerm:     if db_get "$RET"/daemon_name; then
lightdm/DEBIAN/prerm:        db_fset shared/default-x-display-manager seen false
lightdm/DEBIAN/prerm:        db_input critical shared/default-x-display-manager || true
lightdm/DEBIAN/prerm:        db_go
lightdm/DEBIAN/prerm:          db_get shared/default-x-display-manager
lightdm/DEBIAN/prerm:          db_get "$RET"/daemon_name
lightdm/DEBIAN/postinst:  if db_get shared/default-x-display-manager; then
lightdm/DEBIAN/postinst:    if db_get "$DEFAULT_DISPLAY_MANAGER"/daemon_name; then
lightdm/DEBIAN/postinst:db_stop
lightdm/DEBIAN/config:if db_metaget shared/default-x-display-manager owners; then
lightdm/DEBIAN/config:if db_metaget shared/default-x-display-manager choices; then
lightdm/DEBIAN/config:  db_subst shared/default-x-display-manager choices "$OWNERS" || :
lightdm/DEBIAN/config:  db_fset shared/default-x-display-manager seen false || :
lightdm/DEBIAN/config:    db_set shared/default-x-display-manager "$CURRENT_DEFAULT"
lightdm/DEBIAN/config:  if db_get shared/default-x-display-manager; then
lightdm/DEBIAN/config:    db_set shared/default-x-display-manager lightdm
lightdm/DEBIAN/config:    db_fset shared/default-x-display-manager seen true
lightdm/DEBIAN/config:    db_input high shared/default-x-display-manager || :
lightdm/DEBIAN/config:    db_go || :
lightdm/DEBIAN/config:if db_get shared/default-x-display-manager; then

各种db_*函数都是用于处理的辅助函数debconf，从 获得/usr/share/debconf/confmodule。

因此，在 的情况下lightdm，shared/default-x-display-manager是一个重要的debconf关键。