mpkg(1)

Managing packages from a shell script

DESCRIPTION

mPKG is a lightweight package manager written in pure Shell.

As a consequence, it does not require any extra exotic interpreter such as python, ruby, lua...

mPKG uses standard utilities such as sh, grep, tar, wget and awk that are shipped in any POSIX system.

This makes mPKG suitable for embedded devices that usually embed Busybox which provides everything it needs in a single binary.

The project is composed of three scripts:

One run-time script that is designed to be run on the target
Two host build-time scripts that create packages and index

INSTALLATION STEPS

mPKG is simple.

The installation step can be summed up in 3 steps:

Resolving all dependencies
Fetching archive
Unpacking it to root

... nothing more!

INSPIRED BY DEBIAN

The implementation is mostly inspired by Debian packages.

mPKG combines both APT and DPKG features; as Opkg does.

It follows and remains as close as it is relevant to the behavior defined by the Debian policies.

mPKG runs same preinst/postinst and prerm/postrm maintainer scripts.

BUT NOT DEBIAN COMPATIBLE

But mPKG is different.

It is designed for embedded systems which are limited in term of space, memory, and CPU.

mPKG does not have staging directory and unpacks directly archives to the root file system.

Therefore, it does not handle complicated maintainers scripts use-cases to rewind for error handling.

mPKG must remain simple and relies on the maintainers' scripts of the distribution.

CONTROL FIELDS SET

mPKG handles a limited set of control fields.

The essentials archives fields are Package, Version, and Depends.

The index fields Filename and MD5Sum are set in the index to defines the URI where to fetch the archive and its checksum for integrity checking.

It means that there are no Provides, Breaks, Conflicts, and Pre-depends relationships. The goal is to keep mPKG simple.

Furthermore, lists of dependencies are space-separated. It makes the parsing easier in shell scripts because space is one of the default characters of the $IFS variable.

Here is an example of a what a control file looks like:

Package: meta
Version: 2017.11
Depends: busybox mpkg

ARCHIVE FORMAT

Packages are simple.

Debian packages split metadata and data into two distinct archives: control.tar.gz and data.tar.gz.

mPKG archives all data in a single gzipped tar archive.

The archive is an image of the root file system; the package metadata are stored under /var/lib/mpkg.

A minimal package consists of a single file /var/lib/mpkg/info/pn/control containing a single line, where pn is the name of the package.

Package: pn

DATABASE

There is no single file database.

Instead, the status file lets place to a whole file system hierarchy; one directory per package.

It minimizes every not-yet-synchronized write to the monolithic status database. Thus, the impact of critical errors, such as an unexpected reboot, is limited to the concerned package and not the whole database.

mPKG delegates the synchronization to the file system layer.

CLI API

mPKG provides the 3 main operations of a classical package manager:

install
remove
upgrade

TODO

mPKG is still in development.

UPCOMING FEATURES

In the TODO list:

Manage Conffiles and add --purge option when package is removed
Extra features such as whatprovides/whatdepends package or find/search for files are helpful
Index export from control format to HTML or JSON

WONT DO

Here are some features that are not implemented and WILL NOT BE:

version constraints such as Depends: busybox (>= 1.23.1)
Recommends and Suggests relationships; Depends is enough!
Provides, Breaks, and Conflicts; keep relationship simple
the architecture is not essential

INSTALL

mPKG is easy to install.

Because it is a shell script, it does not need to be compiled.

Download mpkg and copy it somewhere in your $PATH.

$ sudo su
# cd /usr/sbin
# wget https://raw.githubusercontent.com/gazoo74/mpkg/master/bin/mpkg
# chmod +x mpkg

mPKG needs at least a repository feed in /etc/mpkg/repo.d/ directory.

# mkdir -p /etc/mpkg/repo.d/
# echo "http://tgz.me/Index" >/etc/mpkg/repo.d/me

AUTHOR

Written by Gaël PORTAY gael.portay@gmail.com

COPYRIGHT

This program is free software: you can redistribute it and/or modify it under the terms of the MIT License.

gportay/mpkg