6.10. 搜尋套件

With the large and ever-growing amount of software in Debian, there emerges a paradox: Debian usually has a tool for most tasks, but that tool can be very difficult to find among the myriad other packages. The lack of appropriate ways to search for (and to find) the right tool has long been a problem. Fortunately, this problem has almost entirely been solved.

最瑣碎的搜尋可能是找到正確的套件名稱。若 apt show 套件名稱 送回結果，表示該套件存在。不幸的是，必須知道或猜對套件名稱，卻幾乎是不可能的.

A slightly more successful searching pattern is a plain-text search in package names, but it remains very limited. You can generally find results by searching package descriptions: since each package has a more or less detailed description in addition to its package name, a keyword search in these descriptions will often be useful. apt-cache and axi-cache are the tools of choice for this kind of search (see 其他 axi-cache); for instance, apt-cache search video will return a list of all packages whose name or description contains the keyword “video”.

更複雜的搜尋，需要更有力的工具，如 aptitude 是其中之一。aptitude 可搜尋套件元資料欄位的內容。例如，以下的範例搜尋含有 kino 字樣的套件名稱，其說明包括 video 與維護者名字為 paul：

$ aptitude search kino~dvideo~mpaul
p   kino  - Non-linear editor for Digital Video data
$ aptitude show kino
Package: kino                     
Version: 1.3.4+dfsg0-1.1
State: not installed
Priority: optional
Section: video
Maintainer: Paul Brossier <piem@debian.org>
Architecture: amd64
Uncompressed Size: 8,316 k
Depends: libasound2 (>= 1.0.16), libavc1394-0 (>= 0.5.3), libavcodec58 (>= 7:4.2),
         libavformat58 (>= 7:4.2), libavutil56 (>= 7:4.0), libc6 (>= 2.29), libdv4
         (>= 1.0.0), libgcc-s1 (>= 3.0), libgdk-pixbuf-2.0-0 (>= 2.22.0),
         libglade2-0 (>= 1:2.6.4-2~), libglib2.0-0 (>= 2.12.0), libgtk2.0-0 (>=
         2.24.0), libiec61883-0 (>= 1.2.0), libpango-1.0-0 (>= 1.14.0),
         libpangoft2-1.0-0 (>= 1.14.0), libquicktime2 (>= 2:1.2.2), libraw1394-11
         (>= 2.1.2), libsamplerate0 (>= 0.1.7), libstdc++6 (>= 9), libswscale5 (>=
         7:4.0), libx11-6, libxext6, libxml2 (>= 2.7.4), libxv1
Recommends: ffmpeg, curl
Suggests: udev | hotplug, vorbis-tools, sox, mjpegtools, lame, ffmpeg2theora
Conflicts: kino-dvtitler, kino-timfx, kinoplus, kino-dvtitler:i386,
           kino-timfx:i386, kinoplus:i386, kino:i386
Replaces: kino-dvtitler, kino-timfx, kinoplus, kino-dvtitler:i386,
          kino-timfx:i386, kinoplus:i386
Provides: kino-dvtitler, kino-timfx, kinoplus
Description: Non-linear editor for Digital Video data
 Kino allows you to record, create, edit, and play movies recorded with DV
 camcorders. This program uses many keyboard commands for fast navigating and
 editing inside the movie. 
 
 The kino-timfx, kino-dvtitler and kinoplus sets of plugins, formerly distributed
 as separate packages, are now provided with Kino.
Homepage: http://www.kinodv.org/
Tags: field::arts, hardware::camera, implemented-in::c, implemented-in::c++,
      interface::graphical, interface::x11, role::program, scope::application,
      suite::gnome, uitoolkit::gtk, use::editing, use::learning,
      works-with::video, x11::application

此搜尋祗找到一個套件，kino，滿足全部三個條件。

Even these multi-criteria searches are rather unwieldy, which explains why they are not used as much as they could. A new tagging system has therefore been developed, and it provides a new approach to searching. Packages are given tags that provide a thematic classification along several strands, known as a “facet-based classification”. In the case of kino above, the package's tags indicate that Kino is a Gnome-based software that works on video data and whose main purpose is editing.

Browsing this classification can help you to search for a package which corresponds to known needs; even if it returns a (moderate) number of hits, the rest of the search can be done manually. To do that, you can use the ~G search pattern in aptitude, but it is probably easier to simply navigate the site where tags are managed or use the debtags command:

→ https://debtags.debian.org/

$ debtags search "works-with::video && use::editing"

以 works-with::video 及 use::editing 標籤可找出若干套件，包括 kino 與 pitivi 影像編輯器。愈來愈多人使用這種分類系統，在此基礎上，套件管理者建立更有效的介面。

總的來說，最好的工具視搜尋複雜度而定：

apt-cache 祗能搜尋套件名稱與說明，很適合搜尋符合少許鍵詞的特定套件；
搜尋對象包括維護者名稱在內的套件關係或其他元資料時，synaptic 就派上用場了；
packagesearch 是圖形介面的標籤型搜尋工具，可搜尋若干領域的套件 (包括套件內的檔案名稱)。命令列的工具，則使用 axi-cache。
最後，需要邏輯運算元的複雜搜尋時，首選工具為 aptitude 的語法，雖然功能強大但較為難用，它有命令列與互動模式兩種介面。