Just right for the start of 2018 I want to introduce two little things to
you. I created...
- ...a prototype AppImage for the IPP Sample Software together with...
- ...a short mini-tutorial introducing some of the IPP Sample utilities.
I. AppImage
===========
An AppImage is a cross-distro Linux packaging method which follows the
philosophy of "One App == One File".
Imagine a macOS ".app" AppDir (application directory) which holds all the
required files for the application at runtime that are not provided by the
base system in the default installation. A Linux AppImage provides a similar
structure -- but with the added improvement of keeping everything in a
single
SquashFS-compressed image. This saves disk space and makes managing the file
trivially easy. When executed, the AppImage gets mounted automatically and
its payload application gets invoked by an embedded "AppRun". Apple and Mac
users will most likely feel very comfortable with handling AppImages.
The AppImage technology is not a competitor to the Snap and Flatpak
packaging, but it is a different thing altogether:
- It is not and does not want to be a package manager.
- It does not need any specific preparation for the target system in order
to work.
- It does not require any extra framework or runtime environment to be
present in order to function.
- It does not need "installation".
- It does not need root privileges for preparing it to work on a system --
runs completely in user space.
- Not being a "package", it simply is an executable which directly runs on
almost any recent Linux distro from the last 3 years.
- It can run from any location (USB thumb drives -- even from remote
shares).
- It can run different versions of the same software without conflict.
- It usually saves disk space (IPP Sample "installed" the traditional way
occupies about 22 MByte on disk; my equivalent AppImage takes only 10
MByte)
- It is easy to get rid of again, should you not like it (just delete the
file).
I can hardly imagine any simpler and more elegant method for distributing
software from developers to its users. Thinking of it, an
"installation-less"
software package is the perfect match for "driver-less" printing :-)
The AppImage project now has more than 10 years of development under its
belt
(though the name is relatively new). AppImages have become pretty popular in
the last 6 months. Meanwhile even Linus Torvalds uses it for an (almost
not-known) end-user GUI application he started a few years ago (which is a
logging, reporting and planning software for hobby and professional divers
called "Subsurface"). He switched to AppImage because he famously thinks
that
"Linux sucks" when it comes to the desktop eco system created by the many
competing Linux distro packaging formats and their library naming crazyness.
Another prominent AppImage user is Microsoft -- they build an AppImage to
provide their PowerShell v6.0.0rc for various Linux distros.
With this AppImage I "pushed the envelope" a bit:
1. AppImages originally were designed for packaging desktop GUI
applications. However, I packaged CLI software with it. This works even
pretty well -- as you will see if you decide to give my IPP Sample
AppImage a spin.
2. While AppImages usually embed ONE executable, I stuffed SEVERAL in: you
can invoke them as 'sub-commands' to the shell 'ippsample', similar to
how 'busybox' works:
ippsample ipptool [ipptool args ...]
ippsample ippproxy [ippproxy args ...]
ippsample ippfind [ippfind args ...]
ippsample ippserver [ippserver args ...]
This is implemented by way of a custom "AppRun" script I wrote for this
AppImage. It also added a few convenience parameters, which may be used:
--listtest List all '.test' files embedded in AppImage
--listtestdoc List all documents which may be used for tests
--listman List all manpages embedded
--listhtml List all HTML docs embedded
--listexe List all executables ('sub-commands') which can be invoked
--listreadme List all embedded README and other text files
--listdir List all directories making up the AppImage
--listfile List all files which make up the AppImage
Additional options then are:
--man <manpage-name> Display named manual page in terminal
--html <HTML-doc-name> Show named HTML doc in default browser
--readme <README-name> Display named README in terminal
Every (recent) AppImage supports these generic CLI parameters:
--appimage-help List other CLI params with short description
--appimage-extract Extract AppImage into the AppDir 'squashfs-root'
This last option, after extraction, lets you hack on my AppRun script should
you feel an itch for this :-)
II. Mini-Tutorial
=================
My tutorial comes in the shape of an "asciinema" ASCIIcast, running about 9
minutes. It should serve as an introductionary HOWTO for the IPP Sample
utilities, as well as a short intro into IPP in general.
Since it uses an AppImage, it can be reproduced immediately after download,
by almost any Linux user who is interested to play with IPP Sample software.
You can watch it here:
- https://asciinema.org/a/155588
Two usage tipps:
1. You can pause or scroll back and then replay a scene it any time if it
was passing by too fast.
2. You can copy'n'paste whatever is interesting for you directly from the
terminal window.
III. Self-promotion
===================
My AppImage is automatically built by Travis CI from a forked
istopwg/ippsample repository on GitHub. If you like it well enough, I can
prepare a pull request for the official istopwg/ippsample repo, and a
working
AppImage will automatically be built and published upon each push
("continuous" release), or upon each officially tagged release, or both.
I'm planning to add a few more functions for user convenience when playing
with this AppImage. Mainly, this is to create a sample of pre-defined print
queues which then can be used for '-C config-dir' invocations of
'ippserver'.
The download location of my current 'xperimental' AppImage is here:
- https://github.com/KurtPfeifle/ippsample/releases/
Please do not miss reading my text-style supplement to the tutorial on the
asciinema.org website. I'd like you to check (and tell me about) if I have
any factual errors in it.
Please let me know about any distro where my AppImage thingie does NOT work!
Cheers, Kurt
P.S.:
------
1. Also please tell me about any other issues you may encounter [1] --
unless
it is a problem with the IPP Sample software itself [2].
2. I promise to not take offense if you consider both, my ASCIIcast and the
AppImage, as two things which put some more weight behind my request from
10 weeks ago to provide *official* AppImage releases by the PWG (see
issue
on GitHub here: https://github.com/istopwg/ippsample/issues/56)
[1]: https://github.com/KurtPfeifle/ippsample/issues
[2]: https://github.com/istopwg/ippsample/issues
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