深入 APT 系统

APT 全称Advanced Package Tool, 系Debian的牛X工具集，功能强大，使用方便，APT是具有牛力的。：）


A. 组件

I. apt-cache

II. apt-get （尚有多种工具，如apt-cdrom apt-setup apt-key ...常用的就这两个)

III. APT configure file
    /etc/apt/apt.conf

IV. source list
    /etc/apt/source.list

V. Packages pool directory
    /var/cache/apt/archives/
                    `----partial/

VI. Local index files from source server
/var/lib/apt/lists/
        |----192.168.10.252_debian_dists_unstable_Release
        |-----192.168.10.252_debian_dists_unstable_Release.gpg
        |-----192.168.10.252_debian_dists_unstable_contrib_binary-i386_Packages
        |-----192.168.10.252_debian_dists_unstable_main_binary-i386_Packages
        |-----lock
        `-----partial/

VII. 安装于系统的软件包的信息记录文件，很重要！可在依赖关系不满足时修改之，让其暂时通过：）
    /var/lib/dpkg/status




B. 有用的配置选项

// From /usr/share/doc/apt/examples/configure-index
Note: These are APT system default value

Dir "/" {
// Location of the state dir     ----------------->Dir::State=/var/lib/apt/
State "var/lib/apt/"
{
  Lists "lists/";             ----------->-o Dir::State::Lists="/tmp/lists/" => /tmp/lists/
  xstatus "xstatus";                   -o Dir::State::Lists="fuck/" => /var/lib/apt/fuck/    
  userstatus "status.user";
  status "/var/lib/dpkg/status";
  cdroms "cdroms.list";
};

// Location of the cache dir
Cache "var/cache/apt/" {
  Archives "archives/";
  srcpkgcache "srcpkgcache.bin";
  pkgcache "pkgcache.bin";
};

// Config files
Etc "etc/apt/" {
  SourceList "sources.list";
  Main "apt.conf";
  Preferences "preferences";
  Parts "apt.conf.d/";
};

// Locations of binaries
Bin {
  methods "/usr/lib/apt/methods/";
  gzip "/bin/gzip";
  dpkg "/usr/bin/dpkg";
  dpkg-source "/usr/bin/dpkg-source";
  dpkg-buildpackage "/usr/bin/dpkg-buildpackage"
  apt-get "/usr/bin/apt-get";
  apt-cache "/usr/bin/apt-cache";
};
                                                                      };

APT
{
Architecture "i386";
Build-Essential "build-essential";

// Options for apt-get
Get
{
  Arch-Only "false";
  Download-Only "false";
  Simulate "false";
  Assume-Yes "false";
  Force-Yes "false";         // I would never set this.
  Fix-Broken "false";
  Fix-Missing "false";
  Show-Upgraded "false";
  Show-Versions "false";
  Upgrade "true";
  Print-URIs "false";
  Compile "false";
  Download "true";
  Purge "false";
  List-Cleanup "true";
  ReInstall "false";
  Trivial-Only "false";
  Remove "true";
  Only-Source "";
  Diff-Only "false";
  Tar-Only "false";
};
};




C. 演示


1. -o apt::get::download-only="true" <==> -d
  To see /usr/share/doc/apt/examples/configure-index


2. apt-get -d -o dir::cache::archives="/tmp/" install emac21
You need to create the directory /tmp/partial/

获取emac21的相关包,置于目录/tmp下, APT系统默认获取的软件包是置于/var/cache/apt/archieves/ 下。

Default: Dir::Cache::archives = /var/cache/apt/archieves/
Note: dir::cache::archives="tmp" ==> /var/cache/apt/tmp/

2.1 apt-get -o dir::cache::archives="/tmp/" clean
delete all *.deb in /tmp/


3. apt-get -o dir::state::lists="/tmp/" update
You need to create the directory /tmp/partial/

从服务器获取软件包索引于 /tmp 下，APT系统默认是置于/var/lib/apt/list 下。
Default: Dir::State::lists = /var/lib/apt/lists/


4. 在已经安装octave2.1 的机器上获取 octave2.1 所需的所有软件包，APT 会解析其所依赖的包，并下载之。
apt-get -d -o dir::cache::archives="/tmp/" -o dir::state::status="/tmp/status" install octave2.1

Note: /tmp/status 拷贝自某台需安装octave2.1 目标机的 /var/lib/dpkg/status




D. Example:

I. 问题描述：
机器A 装有debian-sid，因为特殊的原因没有可用的源；机器B安装debian-sarge，可以获得可靠的deb包，为了稳定一直使用stable的源；现因业务需要对机器A进行升级。

II. 分析
默认情况下，系统安装的软件包状态由 /var/lib/dpkg/status 文件记录(实际上就是安装的软件包信息的汇总)
安装或升级时apt-get 首先会把要用到的包下载到 /var/cache/apt/archives/ 目录下，然后再执行相应的操作(-d 或 -o apt::get::download-only="true" 则仅仅下载)

III. 求解
0. 在机器B的 /tmp下建立工作目录pool/
pool/
|-- archives/
|   `-- partial/
|-- lists/
|   `-- partial/
|-- sources.list     ------------------------------>机器A所用的unstable源
`-- status         ------------------------------>拷贝自机器A的/var/lib/dpkg/status

1.root@A#apt-get
-o dir::etc::sourcelist="/tmp/pool/sources.list" -------------->指定sources.list
-o dir::state::lists="/tmp/pool/lists/" ------>指定Packages,Release文件的存放路径
update
获取APT所要用到的索引文件(如Packages,Release)，并置于/tmp/pool/lists/下。

2.root@A#apt-get -d
-o dir::cache="/tmp/pool/"                   --------->对应于/var/cache/apt/
-o dir::cache::archives="/tmp/pool/archives/" -------->下载之deb包存放目录
-o dir::state::status="/tmp/pool/status"       --------->机器A升级前状态
-o dir::state::lists="/tmp/pool/lists/"
-o dir::etc::sourcelist="/tmp/pool/sources.list" --->APT从该文件获取源类型(unstable,etc.)
dist-upgrade
获取机器A升级所用软件包，存放于/tmp/pool/archives/

3.把pool目录拷入机器A 之 /tmp 目录下
root@B#apt-get -o dir::cache="/tmp/pool/" -o dir::state="/tmp/pool/" -o dir::etc="/tmp/pool/" check
[ APT generates a local copy of the cache files ]


root@B#apt-get -o dir::cache="/tmp/pool/" -o dir::state="/tmp/pool/" -o dir::state::status="/var/lib/dpkg/status" -o dir::etc="/tmp/pool/" dist-upgrade

4.以上过程采用配置文件可简化为：

4.1 建立 apt.conf ,置于pool目录下
apt.conf must contain the necessary information to make APT use the pool:
    APT
    {
    /* This is not necessary if the two machines are the same arch, it tells
      the remote APT what architecture the Debian machine is */
    Architecture "i386";
   
    Get::Download-Only "true";
    };
   
    Dir
    {
    /* Use the disc for state information and redirect the status file from
      the /var/lib/dpkg default */
    State "/tmp/pool/";
    State::status "status";
 
    // Binary caches will be stored locally
    Cache::archives "/tmp/pool/archives/";
    Cache "/tmp/";
   
    // Location of the source list.
    Etc "/tmp/pool/";
    };


4.2 root@A# export APT_CONFIG="/disc/apt.conf"
    root@A# apt-get update
    [ APT fetches the package files ]

    root@A# apt-get dist-upgrade
    [ APT fetches all the packages needed to upgrade your machine ]


4.3 root@B# export APT_CONFIG="/disc/apt.conf"

    root@B# apt-get check
    [ APT generates a local copy of the cache files ]

    root@B# apt-get --no-d -o dir::state::status=/var/lib/dpkg/status dist-upgrade
    [ Or any other APT command ]


以下测试获取 libciao0.4.7

5.apt-get -d
-o dir::cache="/tmp/pool/"
-o dir::cache::archives="/tmp/pool/archives/"
-o dir::state::status="/tmp/pool/status"
-o dir::state::lists="/tmp/pool/lists/"
-o dir::etc::sourcelist="/tmp/pool/sources.list" --->APT从该文件获取源类型(指定unstable)
install   libciao0.4.7


E: Reference

[1] /usr/share/doc/apt/example/configure-index
[2] /usr/share/doc/apt-doc/offline.html/ch2.html