高山Linux下"--update add“命令的解释

Question

我正在尝试理解Dockerfile https://hub.docker.com/r/rdsubhas/tor-privoxy-alpine/~/dockerfile/，它包含一个RUN执行程序，其中包含

apk --update add privoxy tor@testing runit@testing

我想检查一下我对apk命令是如何使用的理解，所以我尝试在阿尔卑斯山环境中打开一个终端，如下所示：

docker run -it --rm alpine:latest /bin/ash

之后，我简单地运行apk来查看它的用法：

/ # apk
apk-tools 2.6.8, compiled for x86_64.

usage: apk COMMAND [-h|--help] [-p|--root DIR] [-X|--repository REPO]
           [-q|--quiet] [-v|--verbose] [-i|--interactive] [-V|--version]
           [-f|--force] [-U|--update-cache] [--progress] [--progress-fd FD]
           [--no-progress] [--purge] [--allow-untrusted] [--wait TIME]
           [--keys-dir KEYSDIR] [--repositories-file REPOFILE] [--no-network]
           [--no-cache] [--arch ARCH] [--print-arch] [ARGS]...

The following commands are available:
  add       Add PACKAGEs to 'world' and install (or upgrade) them, while
            ensuring that all dependencies are met
  del       Remove PACKAGEs from 'world' and uninstall them
  fix       Repair package or upgrade it without modifying main dependencies
  update    Update repository indexes from all remote repositories
  info      Give detailed information about PACKAGEs or repositores
  search    Search package by PATTERNs or by indexed dependencies
  upgrade   Upgrade currently installed packages to match repositories
  cache     Download missing PACKAGEs to cache and/or delete unneeded files
            from cache
  version   Compare package versions (in installed database vs. available) or
            do tests on literal version strings
  index     Create repository index file from FILEs
  fetch     Download PACKAGEs from global repositories to a local directory
  audit     Audit the directories for changes
  verify    Verify package integrity and signature
  dot       Generate graphviz graphs
  policy    Show repository policy for packages
  stats     Show statistics about repositories and installations

Global options:
  -h, --help              Show generic help or applet specific help
  -p, --root DIR          Install packages to DIR
  -X, --repository REPO   Use packages from REPO
  -q, --quiet             Print less information
  -v, --verbose           Print more information (can be doubled)
  -i, --interactive       Ask confirmation for certain operations
  -V, --version           Print program version and exit
  -f, --force             Do what was asked even if it looks dangerous
  -U, --update-cache      Update the repository cache
  --progress              Show a progress bar
  --progress-fd FD        Write progress to fd
  --no-progress           Disable progress bar even for TTYs
  --purge                 Delete also modified configuration files (pkg
                          removal) and uninstalled packages from cache (cache
                          clean)
  --allow-untrusted       Install packages with untrusted signature or no
                          signature
  --wait TIME             Wait for TIME seconds to get an exclusive repository
                          lock before failing
  --keys-dir KEYSDIR      Override directory of trusted keys
  --repositories-file REPOFILE Override repositories file
  --no-network            Do not use network (cache is still used)
  --no-cache              Read uncached index from network
  --arch ARCH             Use architecture with --root
  --print-arch            Print default arch and exit

This apk has coffee making abilities.

问题是，我在本文档中没有看到--update选项(只有--update-cache)。

我怀疑的是，apk --update add [package]仅仅是apk update的缩写，后面跟着apk add [package]。有人能证实这一点吗？

Answer 1

简而言之：

To get the latest list of available packages, use the update command.

它类似于您在apt-get install my_package之前所做的Debian apt-get update。

来自https://wiki.alpinelinux.org/wiki/Alpine_Linux_package_management#Update_the_Package_list

提取

更新包列表

随着包的添加和升级，远程存储库也会发生变化。要获取可用包的最新列表，请使用update命令。该命令从每个存储库下载缓存并将其存储在本地缓存中，通常是/var/ APKINDEX.tar.gz /apk/、/var/lib/apk/或/etc/apk/ cache /。

apk更新

提示:如果使用远程存储库，最好在执行添加或升级命令之前进行更新。这样你就知道你使用的是最新的软件。

Answer 2

请参阅https://github.com/gliderlabs/docker-alpine/pull/503

更新apk --更新标志实际上是--

-cache。

Apk使用getopt_long (3)，https://github.com/alpinelinux/apk-tools/blob/v2.10.3/src/apk.c#L574

因此，getopt_long只将--update标志缩写为--update-cache。

如果长选项名称是唯一的或与某些定义的选项完全匹配，则可以将其缩写。