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The usage of $(variable or function) needs to be removed and replaced with analogous bourne code because its not supported by the bourne shell. And we are aiming for maximum compatibility across all linux distributions.
Unless we find out that by default bash or some form of bash is available on all of our supported linux distributions, we need to build bourne compatible scripts which have a lot less features.
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The primary reason to use bourne sh framework is used for Multiverse OS shell
scripting, and recommended to the user, is because it centralized the
security related responsbilities in shell scripts, implements thorough tests
written for each security related (not completed yet) function.
And all the auxillary logic beyond those security functions and other basic helpers such as OS, validation, and other common utility functions are implemented as small modules.
The modular design of sh framework ensures that the source code footprint
of the framework is as little as possible, and in general, very very small.
This is accomplished by putting most of the logic in small modules that
can be added individually, or piecemal, or altogether. These modules
call the primary framework code sh-framework.sh, the file containing
the important security functionality, the file that tests are primarily
written to test, and provide the common utilties used by the various
modules.
The minimal resource usage of the sh-framework enables it to work
well as a drop in library for rapidly developing simple scripts for minor
tasks or one-offs, or simple commands and macros that simplify common
tasks while providing UI that matches the Multiverse color scheme,
and design patterns, or featureful software and prototyping complex
software.
By centralizing the important security logic of shell scripting, and
providing reliable tests to ensure these feature are working, even
after updates, customizations, in addition to preventing any breaking
changes from being merged into production code. Enabling users of
sh-framework to delegate more difficult security decisions to
both the Multiverse OS developers and the community using the framework,
leaving only the portions of your source code that is unique to your
project, making development not just more secure, but also faster,
easier to learn, and provide UI and functional consistency between
different shell scripts developed by different members of the community.
The important security logic provided by Multiverse OS, will continue to be developed as a component of Multiverse, receive security updates, have additional security features requested by the community or required by Multiverse OS developers. Currently the features are:
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Validations for basic types: strings, numbers, arrays, filepaths, and more...
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User input functions, to securely take in user input and validate the input before using it, beacuse all input should be validated even if the user is assumed to be trusted.
This is how we conform to the security in depth philosphy required by the Multiverse OS design specification, which defines not just the software, and protocols, but also any software included in the Multiverse OS operating system.)
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Tests that ensure any changes to the shell framework do not break existing logic, to avoid any breaking changes from being merged into the production branch and released.
Bash script developers rarely implement tests. And by centralizing security related logic into the framework, and writing tests we believe reliably and reasonably test the security logic.
One important reason why we implemented our own shell framework for Multiverse OS and the users, is not just simply to satisfy our specific prototyping requirements during development, but also to encourage users to develop shell scripts to simplify their computing tasks.
As Multiverse project itself evovles, we want to faciliate P2P nucleatnig points for the Multiverse community and various subcommunities; in a variety of ways. One way we plan to faciliate community participation in ways that we have seen succeed in the past, such as community developed modifications, as seen in video game communities. Constantly improving a growing number of tools, guides, and features of the operating system intended to not only encourage the development of shareable customizations, provide a way for the community to indicate what they like, in a more nuanced way than a simple up/down vote or 1-5 stars.
Enabling Multiverse developers to provide assurance that using this shell
library that will be included by default in Multiverse OS, easily
accessible to users and developers by importing via the use of an
environmental variable (aka ENV; from shell a list can be viewed by using
the env command).
SH_FRAMEWORK="/home/user/.local/share/sh/framework"
For Multiverse OS users this environmental variable is set by default.
However, if you do not yet have the library, or are not using Multiverse OS. Pull the git repository to an accessible location and set the above environmental variable, which will massively simplify importing the framework into shell scripts.
# IF you are not using Multiverse:
sudo su && cd ~/.local/share/ && git clone https://github.com/multiverse-os/sh-framework sh
echo "export SH_FRAMEWORK="~/.local/share/sh/framework.sh" >> ~/.bashrc && source ~/.bashrc
If you are using Multiverse OS, using the framework is very easy, because it is already installed and the environmental variable is already set. So you can skip to this step:
Create a shell script and put some code in it:
#!/bin/sh
sh_import $SH_FRAMEWORK
echo "hello world"
And that is it, you are ready to start using the shell framework functions and rapidly developing great shell scripts.
The environmental variable we are setting is the primary shell script file, it is also imported by all the modules. If you want a module you import it individually.
By default instead of sh_import which we prefer because it is more intuitive
and human readable is an alias of the source. We used the source command to
reload the ~/.bashrc.
In Debian by default, source has a default alias, similar to the default alias
provided by Multiverse OS, this alias is .. This allows a developer to
use the following shorthand during to import the shell framework:
#!/bin/sh
. $SH_FRAMEWORK
The sh_import alias, the variable/function naming in
the source code of the sh-framework, in addition to
all the Multiverse OS source code is directly inspired
by Ruby source code philosophy. Multiverse OS inspired
by the simplicity and accessibility of Ruby.
Currently this framework is designed around the ability to build shell scripts that function in both:
- Debian Linux
- Alpine Linux
In the future, all major linux operating systems and a variety
of micro/uni-kernels will be supported by both Multiverse OS
and the sh-framework. But the alpha release of Multiverse OS
will only guarantee support for the two above operating
systems.
NOTEThis is '/bin/sh' NOT '/bin/bash'.
A folder of examples is included to explicitly show usage examples while providing templates for skeleton scripts that can hasten development of simple Multiverse OS shell scripts.
A test script is included, it is simply made executable chomd +x test.sh and ran in the root of the project. The output will indicate if the tests failed or passed.
Since this is only the second attempt at putting together a simple shell framework, it will be worth doing static analysis on the resulting shell scripts to avoid any major mistakes.
ShellCheck appears to be a good shell script static analysis tool, a few morecould be found and incorporated into the git version control process to avoid majorflaws.