Coding for EasyOS
Page originally written: December 21, 2019
Updated: August 23, 2022; September 19, 2022
This is a page for developers, anyone who creates applications,
utilities, or systems-level scripts, in a variety of languages,
from shell script to compiled languages. If you are interested in
getting involved in EasyOS development, read on...
I, Barry Kauler, am writing this page in the first-person, for
more personal interaction. Any questions, there is a "Contact me"
link at the top of this page -- though do note, although I read
all messages, I don't always reply, or a reply might be delayed --
this is just a question of efficiency of time, and do recognise
that I consider all suggestions, and often have to file them away
for future consideration.
There were lots of development documents created for Puppy Linux,
now archived here:
https://bkhome.org/archive/puppylinux/development/index.html
EasyOS inherits a lot of "puppyisms", so large chunks of those
documents are still relevant. However, the page you are reading
now brings things up-to-date for EasyOS. Incidentally, I often
refer to EasyOS as just "Easy".
Now for some headings to break this page up...
Getting setup for development
It is not necessarily required for shell scripting, but certainly
to compile C/C++/BaCon code, access git and svn repositories,
etc., you will need to have the "devx" SFS loaded.
Easy, like Puppy, provides everything needed for development in a
single SFS file. Easy runs as a layered filesystem, with read-only
'easy.sfs' on the bottom and a read-write folder
(/mnt/wkg/.session) on top. Other SFSs can be inserted between
these two, such as the "devx" SFS.
To obtain the "devx" SFS, click on the "sfs" icon on the desktop,
and there will be an offer to download and install it. You will be
asked whether to install it into a container or the main desktop
-- choose the latter, as compiling inside a container does require
a bit more thought and some caveats.
A reboot is then required, as the Aufs layered filesystem is
created in the initrd. After reboot, type "which gcc" in a
terminal, to confirm that yep, the devx is loaded.
Choice of language: script
Most coding in EasyOS is Bash/Ash shell scripts, from
system-level scripts up to sophisticated GUI applications. Ash is
the shell interpreter provided by Busybox, and is often preferred
as faster than Bash, and has many "bashisms" (and has many more
features than 'dash' used in Debian).
Bash/Ash is fairly easy to learn, and a good way to get into
coding for Linux, any Linux, not just EasyOS. In fact, it is my
recommendation for anyone who asks the question "What language
should I learn for coding in Linux?".
You can create surprisingly sophisticated GUI apps in Bash/Ash.
Mostly we use gtkdialog to provide the GUI frontend.
Documentation for gtkdialog is found at
/usr/share/doc/gtkdialog
I also highly recommend this thread on the Old Puppy Forum, "GtkDialog - tips" created by zigbert:
https://oldforum.puppylinux.com/viewtopic.php?t=38608
Xdialog, xmessage, pupmessage, pupdialog, popup, yaf-splash
...well, you can just type the name in a terminal, ENTER, or
append "--help", for information.
Choice of language: compile
Puppy and Easy developers write some utilities in C. Examples are
the pup_event mechanism and some systray applets such as the
temperature and memory applets.
There are also some utilities written in BaCon, and very
recently, Nim:
 |
BaCon is a BASIC compiler -- well technically not a compiler -- it translates BASIC code to C and then calls gcc. You might find BaCon an easier way to get into compiled coding than C. Here is an introduction to BaCon, with a link to an example GUI application: https://easyos.org/dev/bacon/index.html |
 |
Nim is also a translator, generating C, C++ or
Javascript. Here is an introduction to Nim: |
Continuing with C/C++ compiling...
If you download a source package from somewhere, written in C or C++, and want to compile it, you do the usual steps. However, perform the final "make install" a bit differently:
# ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var --build=x86_64-pc-linux-gnu etc
OR, if source uses cmake:
# cmake . -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_INSTALL_SYSCONFDIR=/etc
# make
# new2dir make install
What that last step does is perform the installation, but also
creates a folder with all of the installed files. It does require
that the folder of the source code is of the format
"<name>-<version>", which is the usual case -- but if
it isn't, like if it is just a name without version, rename the
folder before performing the configure and compile steps.
One other thing: very occasionally 'new2dir' doesn't work, or
works incorrectly. That is a very unusual situation, with a very
odd Makefile, but it can happen. In that case, you will have to do
the normal "make install".
"make install" hint:
If you were forced to do a "make install" and want to find all the installed files. A quick way to find them is to look in /mnt/wkg/.session (or /mnt/.easy_rw/mainrw) -- this is the read-write layer of the aufs layered filesystem, that is, it contains the current session. You could copy these files to manually create a PET, however, be careful that you do not copy any '.wh..*' files -- these are "whiteout" files used by aufs.
Not just 'new2dir', there are other very handy little utilities
for developers. Tabulating them:
| Script | Example |
Description |
| dir2pet |
dir2pet abiword-2.5.6-amd64 |
Convert a directory to a PET
package |
| new2dir |
new2dir make install |
Create a directory of
installed files |
| pet2tgz |
pet2tgz
abiword-2.5.6-amd64.pet |
Convert .pet to .tar.gz
tarball |
| pet2dir |
pet2dir
aiword-2.5.6-amd64.pet |
Convert a .pet to a folder |
| dir2tgz |
dir2tgz abiword-2.5.6-amd64 |
Create a tarball from a folder |
| tgz2pet |
tgz2pet abiword-2.5.6.tar.gz |
Convert a .tar.gz file to PET package |
| dir2sfs |
dir2sfs abiword_2.5.6_amd64 |
Create a SFS from a folder |
| deb2sfs |
deb2sfs abiword_2.5.6_amd64 |
Create a SFS from one or more DEBs |
PET packages are the native package format used in Puppy and
Easy, though other formats such as Debian and Ubuntu DEB packages
are also handled by the PKGget package manager (also known as the
"PPM" -- from the Puppy days, we called it the "Puppy Package
Manager").
After having run the "new2dir make install" step, you can then
run "dir2pet <folder name>" to create a PET package.
Note that 'tgz2pet' is dumb, it just appends a checksum onto the
tarball and renames it to .pet. Certain meta-data that is expected
to be inside the tarball is not created. To create a .pet package
correctly, use 'dir2pet'.
Note, if you had opened up a PET with 'pet2dir' (in a terminal or
via right-click on the PET), it can be closed up again as-is with
'dir2tgz' and 'tgz2pet'.
Some very old information about PET packages is here:
https://bkhome.org/archive/puppylinux/development/createpet.htm
...though note that the ".specs" file inside the PET is now just
named "pet.specs".
You can also create an SFS file from a folder. If you have
compiled an app and installed with "new2dir make install", you
will have a folder, and you can do this:
# dir2sfs <name of folder>
However, the folder must be named in a certain format,
"name_version[-revision]_architecture", for example
"abiword_2.5.6_amd64". Here is a blog post that introduces
dir2sfs:
https://bkhome.org/news/201811/dir2sfs-take-2.html
Another handy hint, make sure that there is "<name>.png" in
usr/share/pixmaps in the folder, as this will be used as the icon
for the container on the desktop. If you don't have that PNG,
dir2sfs will try to find it, and might find an inappropriate
image.
To try out your SFS, copy it to
/mnt/wkg/sfs/easyos/<compatible distro>/<distro
version>/ (ex: /mnt/wkg/easyos/debian/buster), then run menu
"Filesystem -> Easy Boot Manager" and click on the "Load extra
SFS files" button.
...well, that does require it not be already installed, so you
might have to try on a different installation of Easy, or run
"make uninstall".
Note, it is useful to take a snapshot of the session before
compiling, which you can roll back to afterward. To create a
snapshot, go to the menu "Filesystem -> Easy Version Control"
and click the "Snapshot" button. This is great, as you can wipe
out everything installed. The source code that you compiled would
normally be somewhere else, in a partition somewhere, so not in
the .session folder, so will not be affected by snapshot and
rollback.
Menu hierarchy
It is appropriate to mention on this page, as if you create a PET, you will want an entry in an appropriate place in the menu.
The menu hierarchy is different from other Linux distributions. Some users like it, some don't, but it is what it is and you have to live with it. Actually, it is the mere fact of being different that causes initial user resistance, but in time it is found to be OK.
Puppy and Easy have singular hard-coded menu placement. That is, an app can only appear in one place in the menu. The .desktop file, found in /usr/share/applications, has an entry "Categories=", and Puppy/Easy only require one value.
For example, /usr/share/applications/asunder.desktop has this:
Categories=X-Multimedia-sound
To find a suitable value for the "Categories" parameter, look at
this file: /etc/xdg/menus/hierarchy
A couple more hints about creating a Easy-friendly .desktop file:
| Exec=asunder |
Do not preppend a path, nor append anything |
| Name=Asunder audio CD ripper |
Format: <name> <short
description> |
| Icon=asunder.png |
Usually no need for a path |
Regarding the "Icon" parameter, Easy looks in /usr/share/pixmaps,
/usr/local/share/pixmaps, /usr/local/lib/x11/mini-icons,
/usr/local/lib/X11/pixmaps. If anywhere else, a path is
required.
Tags: dev
