我运行了以下命令：
sudo apt-get remove postfix mailutils libsasl2-2 ca-certificates libsasl2-modules
为什么该命令会执行以下操作以及撤消它的最佳方法是什么？
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
couchdb-common erlang-asn1 erlang-base-hipe erlang-crypto erlang-eunit
erlang-inets erlang-mnesia erlang-os-mon erlang-public-key
erlang-runtime-tools erlang-snmp erlang-ssl erlang-syntax-tools erlang-tools
erlang-webtool erlang-xmerl gtk2-engines libbit-vector-perl
libcarp-clan-perl libclass-data-inheritable-perl
libclass-method-modifiers-perl libcommon-sense-perl
libcrypt-openssl-bignum-perl libcrypt-openssl-rsa-perl libdata-random-perl
libdate-calc-perl libdate-calc-xs-perl libenet2a libextutils-depends-perl
libextutils-pkgconfig-perl libgd-perl libgnome2-canvas-perl
libgnome2-wnck-perl libgoo-canvas-perl libgoocanvas-common libgoocanvas3
libgtk2-appindicator-perl libgtk2-imageview-perl libgtk2-unique-perl
libgtkimageview0 libhttp-server-simple-perl libjs-prototype
libjs-scriptaculous libjson-perl libjson-xs-perl libmouse-perl
libmozjs185-1.0 libpath-class-perl libproc-processtable-perl
libproc-simple-perl libsctp1 libsort-naturally-perl libtie-ixhash-perl
libunique-1.0-0 libx11-protocol-perl libxml-xpathengine-perl lksctp-tools
perlmagick supertuxkart-data
Use 'apt-get autoremove' to remove them.
The following extra packages will be installed:
libxml-libxml-perl
The following packages will be REMOVED
account-plugin-aim account-plugin-yahoo aisleriot apt-transport-https apturl
atom ca-certificates checkbox-gui checkbox-ng checkbox-ng-service
chromium-browser chromium-browser-l10n compiz compiz-gnome couchdb
couchdb-bin curl darktable deja-dup-backend-gvfs evolution-data-server
gconf-service gconf-service-backend gconf2 gir1.2-gdata-0.0 git
gnome-contacts gnome-terminal gnome-terminal-data gnome-user-share
gstreamer0.10-plugins-bad gstreamer1.0-plugins-bad gvfs-backends
indicator-applet kerneloops-daemon libbonoboui2-0 libcmis-0.4-4 libcurl3
libcurl3-gnutls libflickcurl0 libfolks-eds25 libgconf2-4 libgdata13
libgnome2-0 libgnome2-bin libgnome2-common libgnome2-gconf-perl
libgnome2-perl libgnome2-vfs-perl libgnomeui-0 libgnomevfs2-0
libgnomevfs2-common libgnomevfs2-extra libldap-2.4-2 libldb1
liblwp-protocol-https-perl libmailutils4 libnet-dbus-perl
libnet-dropbox-api-perl libnet-oauth-perl liboauth0 libpanel-applet-4-0
libpurple0 libraptor2-0 librasqal3 librdf0
libreoffice-avmedia-backend-gstreamer libreoffice-base-core libreoffice-calc
libreoffice-core libreoffice-draw libreoffice-gnome libreoffice-gtk
libreoffice-help-en-us libreoffice-impress libreoffice-math
libreoffice-ogltrans libreoffice-pdfimport
libreoffice-presentation-minimizer libreoffice-writer libruby1.9.1
libsasl2-2 libsasl2-modules libslv2-9 libsmbclient libspice-server1
libwww-mechanize-perl libwww-perl libxml-parser-perl libxml-sax-expat-perl
libxml-twig-perl mailutils mythes-en-us nautilus-share network-manager-gnome
oneconf oneconf-common postfix python-cupshelpers python-gconf python-gnome2
python-httplib2 python-ldb python-oneconf python-piston-mini-client
python-pycurl python-requests python-samba python-smbc
python-ubuntu-sso-client python3-checkbox-ng python3-httplib2
python3-oneconf python3-piston-mini-client python3-pycurl python3-requests
python3-software-properties python3-uno redshift ruby ruby1.9.1
samba-common-bin samba-libs seahorse shutter smbclient software-center
software-center-aptdaemon-plugins software-properties-common
software-properties-gtk spotify-client steam-launcher supertuxkart
system-config-printer-common system-config-printer-gnome
system-config-printer-udev telepathy-haze transmission-gtk ubuntu-desktop
ubuntu-sso-client ubuntu-sso-client-qt unity unity-lens-photos
unity-scope-gdrive unity-scope-musicstores vlc vlc-nox vlc-plugin-notify
vlc-plugin-pulse whoopsie xserver-xorg-video-all xserver-xorg-video-qxl
The following NEW packages will be installed
libxml-libxml-perl
0 to upgrade, 1 to newly install, 151 to remove and 9 not to upgrade.
Need to get 337 kB of archives.
After this operation, 1,072 MB disk space will be freed.
Do you want to continue? [Y/n]
答案1
依赖项
许多这样的软件包依赖于一个名为的软件包ubuntu-desktop。
现在您尚未选择删除它 - 它不在此列表中：
postfix mailutils libsasl2-2 ca-certificates libsasl2-modules
但请注意包装ca-certificates。
我运行了这个命令：
apt-cache rdepends postfix mailutils libsasl2-2 ca-certificates libsasl2-modules
它返回一个列表，如下所示：
postfix
Reverse Depends:
|ubumirror
postfix-policyd-spf-python
postfix:i386
...
mailutils
Reverse Depends:
heirloom-mailx:i386
bsd-mailx:i386
...
libsasl2-2
Reverse Depends:
libvirt0
libvirt-bin
mutt-patched
libkmanagesieve4
libkldap4
libkimap4
...
ca-certificates
Reverse Depends:
google-chrome-unstable
google-chrome-stable
google-chrome-beta
ubuntu-touch
...
ubuntu-desktop
...
libsasl2-modules
Reverse Depends:
xubuntu-desktop
ubuntustudio-desktop
ubuntu-gnome-desktop
sendmail-bin
...
ca-certificates在这里很重要，因为ubuntu-desktop取决于它。
很多东西都需要ubuntu-desktop。很多。如果你移除它们，很多东西都会损坏 - 所以不要移除它们。如果必须移除，请不要移除ca-certificates- 你为什么要这么做？
答案2
这是因为删除其中一些包会破坏其他包的依赖关系。
你最好不要同意删除该内容。
如果你已经删除了所有内容，你可以通过以下方式恢复
sudo apt-get install ubuntu-desktop
但没有人能保证一切都能恢复。
您可以查看/var/log/apt/history.log已删除的内容。然后安装缺失的软件包。
但ubuntu-desktop即使不是全部，也应该撤掉大部分。
根据您的具体情况不要删除ca 证书