Overview of the ipkg package management system

From NAS-Central Buffalo - The Linkstation Wiki

Latest revision as of 04:22, 28 August 2011

This article is based on original work from nix and edited by frontalot from www.linkstationwiki.org

Overview

ipkg (officially iPKG) is a lightweight, simplistic package management system. A package management system does just that -- it manages precompiled software which has been bundled into modular, interdependent packages.

ipkg was originally designed for embedded systems such as the iPAQ but works equally well for small Linux systems such as the LinkStation. ipkg allows for dynamic installation/removal of software packages and dependency checking, much like Debian's dpkg system. The ipkg system is being used quite successfully by several embedded Linux hacking groups such as OpenWRT and NSLU2-Linux. Documentation at the official ipkg home page is sparse and in some instances inaccurate. We will try to cover as much information as possible here.

Advantages

• The ipkg client and libraries are relatively small

• The installed meta-data is minimal yet fully functional

• Actively maintained

• Well developed, active user base

Disadvantages

• Limited features, e.g., extra scripts are required to set up users or groups

• Documentation is limited and often outdated or inaccurate

• Significant changes in development can cause incompatibilities between versions

• Root access is generally required to build a package and to install a package

• Limited control over owner, group, and access permissions of package contents

The Client

Client Program Name
On some platforms the ipkg client program is named ipkg-cl. The ipkg system on the LS is controlled through a single client program, the appropriately named ipkg. It is used to install, remove, and manage packages. ipkg is capable of obtaining packages from a remote server called a feed, similar to Debian's apt-get functionality. It can also install packages from a provided .ipk package file.

ipkg documentation
Some ipkg commands and options are not properly documented here. This is due to the fact that ipkg in general comes without any documentation. To understand the exact working of some of the commands the study of the source code is required. Please add documentation for commands and options if you are becoming aware of their working.

The following is a list of available commands for the ipkg client:

usage: ipkg [options...] sub-command [arguments...]

Package manipulation sub-commands

update

Update list of available packages

upgrade

Upgrade all installed packages to latest version

install pkg

Download and install pkg (and dependencies)

install file.ipk

Install package file.ipk

configure [pkg]

Configure unpacked packages

remove pkg

Remove package pkg

flag flags pkg ...

Flag package(s) pkg (flag=hold|noprune|user|ok|installed|unpacked (one per invocation))

Informational sub-commands

list

List available packages and descriptions

files pkg

List all files belonging to pkg

search file

Search for a package providing file

info [pkg [field]]

Display all/some info fields for pkg or all

status [pkg [field]]

Display all/some status fields for pkg or all

download pkg

Download pkg to current directory

compare_versions v1 op v2

compare versions using <= < > >= = << >>)

print_architecture

Prints the architecture

print_installation_architecture

?

whatdepends [-A] [pkgname|pat] 

List all packages that depend on pkgname

whatdependsrec [-A] [pkgname|pat] 

Variation of whatdepends?

whatprovides [-A] [pkgname|pat] 

List all packages that provide pkgname

whatconflicts [-A] [pkgname|pat] 

List all packages that conflict with pkgname

whatreplaces [-A] [pkgname|pat] 

List all packages that replace pkgname

Options

-A

Query all packages with whatdepends, whatprovides, whatreplaces, whatconflicts

-V level

Set verbosity level to level. If no value is provided increase verbosity by one

--verbosity=level

Verbosity levels:

0

errors only

1

normal messages (default)

2

informative messages

3

debug output

-f conf_file

Use conf_file as the ipkg configuration file

--conf conf_file

Default configuration file location is /etc/ipkg.conf

-d dest_name

Use dest_name as the the root directory for package installation, removal, upgrading

--dest=dest_name

dest_name should be a defined dest name from the configuration file

-o offline_root

Use offline_root as the root directory for offline installation of packages

--offline=offline_root

Use offline_root as the root directory for offline installation of packages

--verbose_wget

More wget messages

Force Options

These options are used to override a decision ipkg would otherwise make on its own.

-force-depends

Make failed dependency-checks warnings instead of errors and install/remove package in spite of failed dependencies

-force-defaultsv

Use default options for questions asked by ipkg. This will not prevent package installation scripts from prompting

-force-reinstall

Allow ipkg to reinstall a package

-force-overwrite

Allow ipkg to overwrite files from another package during an install

-force-removal-of-dependent-packages

-force_space

Install even if there does not seem to be enough space

-noaction

No action -- test only

-nodeps

Do not follow dependencies

-recursive

Allow ipkg to remove package and all that depend on it

-test

No action -- test only

-t tmp-dir

Specify temporary directory

--tmp-dir=tmp-dir

Specify temporary directory

Please see Ipkg on the Linkstation (for end-users) for more information on how to use ipkg on the LinkStation.

The Configuration Files

The configuration files control the server(s) from which ipkg update and ipkg get will pull package information and packages. /etc/ipkg.conf Defines destination locations, feeds and global and proxy settings. Each line in the file is either a comment, an empty line (ignored), or consists of a configuration parameter. The following parameters are supported:

# comment

Comments

src feed-name feed-url

Name and location of a feed.

dest dest-name dest-location

Installation destination name and directory.

option name value

Configuration options. Option names are:

http_proxy

Proxy to use for HTTP connections

ftp_proxy

Proxy to use for FTP connections

proxy_username

Proxy user name

proxy_password

Proxy password

offline_root

Root for offline installation, e.g. into some flash memory.

/etc/ipkg/feed-name.conf
There isn't any official documentation for the contents of feed-name.conf files

/etc/ipkg/feed-name.conf 

Defines feed-specific settings for the feed feed-name.

The Packages

The software packages are contained in special .ipk files. An .ipk file is a specially constructed ar archive (previous versions of .ipk files were gzipped tar archives, like .deb files - this is a discouraged but still supported format) containing three parts:

./data.tar.gz

Contains the actual files belonging to this package, organized as they should appear after installation

./control.tar.gz

Contains a file describing the package meta-data and any installation/removal scripts for the package

./debian-binary

This file is for comparability with Debian's package system and currently is ignored by ipkg

See Construct ipkg packages (for developers) for an in-depth discussion of the package format.