My-Alternatives
(hacking update-alternatives to make local changes)

My-Alternatives is a light-weight wrapper over update-alternatives, offering user-level customizations.

Supports Debian, SUSE^*, and RedHat

_{* for suse support, use the debian version}

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Easy to Get Started

With my-alternatives, configuring custom alternatives is as easy as:

home configuration example

    # initialize my-alternatives
    # note: place this in your .profile
    $ eval "$( my-alternatives init )"

    # customize an alternative
    $ my-alternatives select <name>

Your selections will be saved into your HOME configuration, and made active in any login shell that performs the initialization routine.

NOTE: You can save the initialization routine in your .profile

Per-Shell Configuration

If you want to make a temporary change that only modifies your current shell session, you can initialize a TEMP configuration:

temp configuration example

    # initialize a temporary configuration
    # note: your HOME configuration must already be initialized
    $ my-alternatives init-tmp

    # customize an alternative for just the current shell
    $ my-alternatives select <name>

Auto-Import

The first time you select an alternative, my-alternatives automatically imports the alternative group into your configuration.

When the HOME configuration is the active configuration, my-alternatives imports the group from the system-level configuration.

When a TEMP configuration is active, my-alternatives first tries to import from your HOME configuration, falling back onto the system-level configuration if the group is not present.

Manual Import

If you want to import an alternative group into your active configuration without selecting an alternative, you can use the import command:

import example

$ my-alternatives import <name>

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Commands

Below are tables of the available commands for each supported OS

Debian / SUSE

NOTE: SUSE uses a rebranded version of Debian's udpate-alternatives.

Until such time as the feature set of the two versions diverges, this project will just maintain the Debian vesion.

My-Alternatives-Debian Commands

Below is the list of custom commands that my-alternatives-debian implements:

Command	Description
init, shellenv	Prepare the current shell session for user-level alternatives.
init-tmp, tmp	Configure the current shell session for temporary (short-lived) changes.
rm-tmp	Remove the temporary configuration from the current shell session, making the HOME configuration active.
select, config	Select the active alternative for a group. This is equivalent to update-alternatives --config with the adition of the auto-import logic.
import	Import an alternative group into the current configuration.
add	Add an alternative to a group within the current configuration. This is equivalent to update-alternatives --install but has slightly different syntax. see my-alternatives help add for details.
version	Display my-alternatives version number.

NOTE: See my-alternatives help <command> to learn about a specific command, including additional options.

Debian Update-Alternatives Commands

Below is the list of commands that are implemented as pass-through to the related Debian update-alternatives command:

My-Alternatives Command	Update-Alternatives Command
select, config	--config
select-all, --config-all	--all
rm-alt	--remove
rm-group, rm-grp	--remove-all
query	--query
display	--display
list	--list
set	--set
auto	--auto
get-selections	--get-selections
set-selections	--set-selections
ua-help	--help
ua-version	--version

My-Alternatives will set the --admindir and --altdir options to point to your active configuration.

All additional command-line options are passed-through, unmodified.

NOTE: See update-alternatives --help or man update-alternatives to learn more about the various commands and their options.

RedHat

hacking The system

RedHat has its own implementation of update-alternatives, which is slightly different from the Debian version.

One major difference is that it does NOT support the --query option, meaning that there's no means of determining an anternative's full configuraiton using just the tool's public API.

In order to support this version, we have to use knowledge of the system's private API. Namely:

• Defaulting the "admin" directory to /var/lib/alternatives
• Assuming the name and format of files in the admin directory
• Defaulting the "alt" directory to /etc/alternatives
• Assuming the name and nature of files in the alt directory

My-Alternatives-RedHat Commands

Below is the list of custom commands that my-alternatives-redhat implements:

Command	Description
init, shellenv	Prepare the current shell session for user-level alternatives.
init-tmp, tmp	Configure the current shell session for temporary (short-lived) changes.
rm-tmp	Remove the temporary configuration from the current shell session, making the HOME configuration active.
select, config	Select the active alternative for a group. This is equivalent to update-alternatives --config with the adition of the auto-import logic.
import	Import an alternative group into the current configuration.
add	Add an alternative to a group within the current configuration. This is equivalent to update-alternatives --install but has slightly different syntax. see my-alternatives help add for details.
add-child	Add an child to an existing alternative for a group within the current configuration. This is equivalent to update-alternatives --add-slave but has slightly different syntax. see my-alternatives help add-child for details.
version	Display my-alternatives version number.

NOTE: See my-alternatives help <command> to learn about a specific command, including additional options.

RedHat Update-Alternatives Commands

Below is the list of commands that are implemented as pass-through to the related RedHat update-alternatives command:

My-Alternatives Command	Update-Alternatives Command
select, config	--config
add-child	--add-slave
rm-alt	--remove
rm-group, rm-grp	--remove-all
rm-child	--remove-slave
display	--display
list	--list
set	--set
auto	--auto
ua-help	--help
ua-version	--version

My-Alternatives will set the --admindir and --altdir options to point to your active configuration.

All additional command-line options are passed-through, unmodified.

NOTE: See update-alternatives --help or man update-alternatives to learn more about the various commands and their options.

Invoking Update-Alternatives Directly

If you need to pass a specific command to update-alternatives, you can do so using the ua command:

invoke update-alternatives directly

$ my-alternatives ua --display pager

My-Alternatives will set the --admindir and --altdir options to point to your active configuration.

All additional command-line options are passed-through, unmodified.

NOTE: See update-alternatives --help or man update-alternatives to learn more about available commands and their options.

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Installing

Releases

See the Releases page for downloadable archives of versioned releases.

Git

git clone git://github.com/TekWizely/my-alternatives.git

Renaming the Scripts

Depending on how you acquire the files, the scripts may be named by their OS flavor, i.e:

• Debian : my-alternatives-debian
• RedHat : my-alternatives-redhat

Feel free to rename them as desired. Personally, I rename the script AND set up a few convenient aliases:

$ cp my-alternatives-debian ~/bin/my-alternatives
$ alias ma="my-alternatives"
$ alias mua="my-alternatives ua"

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Contributing

To contribute to My-Alternatives, follow these steps:

1. Fork this repository.
2. Create a branch: git checkout -b <branch_name>.
3. Make your changes and commit them: git commit -m '<commit_message>'
4. Push to the original branch: git push origin <project_name>/<location>
5. Create the pull request.

Alternatively see the GitHub documentation on creating a pull request.

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Contact

If you want to contact me you can reach me at TekWizely@gmail.com.

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License

The tekwizely/my-alternatives project is released under the MIT License. See LICENSE file.

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Misc Notes

As of v0.7.0, my-alternatives has been split (and renamed) into two scripts: my-alternatives-debian and my-alternatives-redhat.

As of v0.6.0, my-alternatives is a complete re-write. As much as possible, commands are implemented as pass-through to update-alternatives, pointing to your active configuration.

My-Alternatives does not require root / sudo privileges to use, as it creates and maintains user-owned configuration directories.

CAVEATS:

• Written in Bash
• Requires the following system tools:
  • update-alternatives
  • readlink (redhat version)
  • mktemp (debian version)
  • umask
  • dirname
  • basename
  • manpath (optional)
• Utilizes tmp files / directories
  • Sets umask 077 for safety
• Tested on:
  • Ubuntu
    • Ubuntu 20.04.3 LTS
    • Debian update-alternatives version 1.19.7.
    • Bash 5.0.17(1)-release
  • openSUSE
    • openSUSE Leap 15.3
    • SUSE update-alternatives version 1.19.0.4.
    • Bash 4.4.23(1)-release
  • CentOS
    • CentOS Linux release 8.4.2105
    • alternatives version 1.13
    • GNU bash, version 4.4.19(1)-release