Because only in the best Shells you will find a Pearl...
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Table of Contents
- Description
- Quickstart
- Installation
- Create your own Pearl package in seconds!
- Create your own Pearl repository in seconds!
- Troubleshooting
- Contributing
Pearl is a lightweight package manager for automating reproducible environments between different systems (Linux and OSX). It can be used for dotfiles, plugins, programs and any form of code accessible via git.
As soon as a package gets installed, its content can be activated out of the box according to certain events, like, for instance, a shell startup (Bash, Zsh or Fish) or an editor startup (Vim or Emacs). This is possible via a smart and simple hook mechanism that integrates the package content within the Pearl ecosystem.
The main advantages on using Pearl are:
- Create your own Pearl package in seconds (any git repository is already a Pearl package)!
- Full control and sync of your dotfiles across different systems.
- Automatic bootstrap of the package content whenever shells or editors get started.
- Access to a wide range of existing packages via the OPH (Official Pearl Hub).
- Allows to create your own package repository that can be shared with your friends!
- Stable codebase with 100+ unit tests and exhaustive integration tests via Travis for Linux and OSX.
- Small number of dependencies needed in order to ensure compatibility with most of the systems.
You could achieve something similar from what Pearl provide by using Ansible. Ansible is a powerful software for IT automation which can be widely used for many use cases. Despite of this, Ansible has few drawbacks when using it for lightweight forms of automations:
- Pearl uses bash for writing simple scripts for automation:
- it makes easier the integration with other programs in the system (without existing Playbooks may be hard and tedious to achieve this in Ansible);
- bash is a powerful, accessible and well-known language;
- Ansible requires way more dependencies than Pearl;
- Ansible requires knowledge about how Ansible Playbooks works;
- Pearl uses built-in functions and variables which heavily simplify construction of scripts for automation;
- Pearl makes easier to remove packages and restore the system to an initial state;
The Pearl command allows to: list, search, install, update, emerge,
remove the Pearl packages defined according to the configuration located in
$XDG_CONFIG_HOME/pearl/pearl.conf (defaults to ~/.config/pearl/pearl.conf)
- List all the available packages:
$ pearl list
...
pearl/dot-git
Awesome git dotfiles (https://github.com/pearl-hub/git)
pearl/sesaila [installed]
Awesome aliases for Bash, Zsh and Fish shells (https://github.com/pearl-hub/sesaila)
pearl/airline [installed]
Status/tabline for vim (https://github.com/vim-airline/vim-airline)
pearl/trash-cli [installed]
Command line interface to the freedesktop.org trashcan (https://github.com/pearl-hub/trash-cli)
...- Search for
vimPearl packages:
$ pearl search vim
* Updating https://github.com/pearl-hub/repo.git repository
pearl/dot-vim
Awesome vim dotfiles (https://github.com/pearl-hub/vim)- Install
pearl/dot-vimpackage (as soon as the package is installed the package is ready out of the box in vim editor!):
$ pearl install dot-vim
* Updating https://github.com/pearl-hub/repo.git repository
* Installing pearl/dot-vim package- Install
pearl/trash-clipackage:
$ pearl install trash-cli
* Updating https://github.com/pearl-hub/repo.git repository
* Installing pearl/trash-cli package
$ trash -h
Usage: trash [OPTION]... FILE...
Put files in trash
...
...- Update
pearl/dot-vimpackage:
$ pearl update dot-vim
* Updating https://github.com/pearl-hub/repo.git repository
* Updating pearl/dot-vim package- Update Pearl and all its packages installed:
$ pearl update
...
* Updating https://github.com/pearl-hub/repo.git repository
* Updating Pearl script
* Updating pearl/dot-vim package
* Updating pearl/airline package
* Updating pearl/trash-cli package
* Updating pearl/caprica package
...Emerge is an idempotent command for either installing or updating a package depending whether the package is already installed or not. This command turns to be particularly useful for establishing dependencies between packages. See the section below for more details.
- Remove
pearl/dot-vimpackage:
$ pearl remove dot-vim
* Updating https://github.com/pearl-hub/repo.git repository
* Removing pearl/dot-vim package- Remove Pearl and all its packages installed:
$ pearl remove
...
Are you sure to REMOVE all the Pearl packages in $PEARL_HOME folder? (N/y)
* Updating https://github.com/pearl-hub/repo.git repository
* Removing pearl/dot-vim package
* Removing pearl/airline package
* Removing pearl/trash-cli package
* Removing pearl/caprica package
...For dotfiles packages take a look here.
Check out the OPH (Official Pearl Hub) for more packages you might be interested.
Before installing Pearl be sure that all dependencies are properly installed in your system. The Pearl dependencies are the following:
The following are not mandatory dependencies but can be handy to have for the hook functions in Pearl package. All the Linux distributions have these dependencies already installed.
Pearl supports also the following shells:
Assuming all Pearl dependencies are properly installed
in the system, to install Pearl you can use the pip command.
Unless there is a specific use case, it is not a good option to use virtual environments such as
virtualenv or conda because otherwise Pearl will be only visible within that environment.
It is recommended to use the system-wide pip which is generally locate in /usr/bin/pip.
The following will install the package in your $HOME directory (~/.local/):
/usr/bin/pip install --user pearlcli
export PATH="~/.local/bin:$PATH"
Pearl command will be located in ~/.local/bin/pearl
To create the $PEARL_HOME directory and the new pearl configuration file from template, run:
pearl init
In order to install all Pearl dependencies, you first need to install Homebrew.
To install all the needed dependencies via Homebrew:
brew update
brew install bash git coreutils grep gnu-sed pythonUnless there is a specific use case, it is not a good option to use virtual environments such as
virtualenv or conda because otherwise Pearl will be only visible within that environment.
It is recommended to use the system-wide pip which is generally locate in /usr/bin/pip.
The following will install the package in your $HOME directory (~/.local/):
/usr/bin/pip install --user pearlcli
export PATH="~/.local/bin:$PATH"
Pearl command will be located in ~/.local/bin/pearl
To create the $PEARL_HOME directory and the new pearl configuration file from template, run:
pearl init
IMPORTANT NOTE: Pearl gets loaded through ~/.bashrc. The problem is that in OSX,
the terminal opens a login shell and only ~/.bash_profile will get executed.
Run the following only if ~/.bashrc is not loaded within ~/.bash_profile file:
echo "[[ -f ~/.bashrc ]] && source ~/.bashrc" >> ~/.bash_profileThis will make sure that ~/.bashrc will run at shell startup.
Any git repository is already a Pearl package. For instance, in order
to manage a dotfiles repository in Pearl, you just need to change
the Pearl configuration file located in $XDG_CONFIG_HOME/pearl/pearl.conf.
Add the following line to pearl.conf file:
PEARL_PACKAGES = {
"mydotfiles": {
"url": "https://github.com/user/mydotfiles.git",
"description": "My dotfiles"
},
}
In other words, update the PEARL_PACKAGES dictionary with a new entry containing the
name of the package (i.e. mydotfiles),
the git url (i.e. https://github.com/user/mydotfiles.git) and an optional description.
That's it! The package will be ready to be installed, updated, emerged and removed via the Pearl system.
Your own git repository can contain an optional directory
named pearl-config used by Pearl to integrate the package with the Pearl environment.
/ (package root)
│
├── pearl-config (optional directory)
│ │
│ ├── install.sh
│ ├── config.sh
│ ├── config.bash
│ ├── config.zsh
│ ├── config.fish
│ ├── config.vim
│ └── config.el
│
└── (additional package content)
The files inside pearl-config are also optional scripts:
install.sh- contains the hooks functions executed during theinstall,updateandremoveevents.config.sh- will be sourced whenever a new Bash/Zsh shell is starting up.config.bash- will be sourced whenever a new Bash shell is starting up.config.zsh- will be sourced whenever a new Zsh shell is starting up.config.fish- will be sourced whenever a new Fish shell is starting up.config.vim- will be executed whenever Vim editor is starting up.config.el- will be sourced whenever Emacs editor is starting up.
The following variables can be used in any of the previous scripts:
PEARL_HOME- Pearl location ($XDG_DATA_HOME/pearlwhich by default is$HOME/.local/share/pearl)PEARL_PKGDIR- Pearl package locationPEARL_PKGVARDIR- Pearl package location containing data needed for packagePEARL_PKGNAME- Pearl package namePEARL_PKGREPONAME- Pearl package repo name (useful to detect and interact with packages within the same repo)
Additionally, the script install.sh can use the utility functions available in
Buava and Pearl utils directory that
make easier the integration with Pearl ecosystem.
Useful examples of Pearl packages can be checked in the Official Pearl Hub.
post_install- Called after an installation of the package occurs.pre_update- Called before an update of the package occurs.post_update- Called after an update of the package occurs.pre_remove- Called before a removal of the package occurs.
post_install() {
warn "Remember to setup your config located in: ~/.dotfile"
# Do a smart backup before modifying the file
backup ${HOME}/.dotfile
"# New dotfile" > ${HOME}/.dotfile
link tmux "$PEARL_PKGDIR/mytmux.conf"
info "Awesome - new package installed!"
return 0
}
post_update() {
post_install
return 0
}
pre_remove() {
info "dotfiles package removed"
unlink tmux "$PEARL_PKGDIR/mytmux.conf"
# Do an idempotent delete
delete ${HOME}/.dotfile
return 0
}
The info and warn are functions that print a message
using different colors (namely cyan and yellow).
The link unlink are idempotent functions (the result will not change
if the function will be called multiple times) that are able
to link/unlink a config file in order to be loaded at startup by a certain program.
The backup keeps the last three backups of the file and do not perform backup
if the file has not been modified since the latest backup. The delete is a
function for idempotent remove (it will not raise an error if the file
no longer exist).
All these functions belong to the Buava package
in utils.sh
and to the Pearl utils.sh script. You can use them
inside the install.sh to any hook function.
Very important note: All the hook functions must be idempotent (the commands of each hook function must produce the same result even if the command gets executed multiple times). All buava commands are idempotent and this will help to write hook functions very quickly.
Note: For OSX system, the GNU version sed and grep are automatically
imported in install.sh and can be directly used if needed.
Pearl package system will work even for local directories. This is particularly useful whenever a Pearl package needs to be tested before pushing to a git repository.
For instance, the following lines in pearl.conf file will add a package located in
/home/joe/dotfiles:
PEARL_PACKAGES = {
"mydotfiles": {
"url": "/home/user/mydotfiles",
"description": "My dotfiles"
},
}
The directory path must be an absolute path.
The package will be ready to be installed, updated, emerged and removed via the Pearl system.
The directory content can be structured in the exact way as described in the section above.
Suppose you have a package mypack which depends on another package mydep,
you can update the mypack install.sh file in this way:
post_install() {
# Install/update the dependency here:
pearl emerge ${PEARL_PKGREPONAME}/mydep
}
post_update() {
post_install
}
pre_remove() {
# Uncomment below to strictly remove the dependency
# during the removal of the current package:
#pearl remove ${PEARL_PKGREPONAME}/mydep
}
The PEARL_PKGREPONAME variable will make sure to define dependencies only
between packages of the same repository.
To see a real example in Pearl Hub, take a look at the Kyrat install.sh.
If you want to use a third-party git repository that is not available in the Official Pearl Hub, you can:
- Create your own git repository and use the
PEARL_PKGVARDIRdirectory (recommended) - Create your own git repository and use git submodule
- Point directly to the third-party git repository
To see examples of Pearl packages from third-party git repos take a look at the Official Pearl Hub.
You can use the PEARL_PKGVARDIR directory during the installation phase to install the third-party git repository.
This is the best way to incorporate third-party project into Pearl ecosystem.
Here it is an example of install.sh file which install the ranger file manager into the directory ${PEARL_PKGVARDIR}/ranger:
function post_install(){
install_or_update_git_repo https://github.com/ranger/ranger.git "${PEARL_PKGVARDIR}/ranger" master
}
function post_update(){
post_install
}
function pre_remove(){
rm -rf ${PEARL_PKGVARDIR}/ranger
}
The function install_or_update_git_repo comes from the Buava
library in utils.sh
which is natively available in Pearl during the installation.
You can even use the functions install_git_repo or update_git_repo which respectively install or update the git repository.
For a full example take a look at the ranger Pearl Hub package.
Inside your git repository, you just need to add the third-party git repo as a
git submodule.
For instance, to add the powerline in your Pearl package,
you can introduce a submodule in the module directory:
git submodule add https://github.com/powerline/powerline.git module
The filesystem structure of the package will become something like this:
/ (package root)
│
├── pearl-config (optional directory)
├── module/ (contains third-party code)
└── (additional package content)
Then, you just need to modify the config scripts in order to integrate the third-party project inside Pearl environment.
Let's suppose you want to install the vim-rails plugin.
In your Pearl configuration ($XDG_CONFIG_HOME/pearl/pearl.conf), add your new Pearl package:
PEARL_PACKAGES = {
"vim-rails": {
"url": "https://github.com/tpope/vim-rails.git",
"description": "Ruby on Rails power tools"
},
}
Install the package:
pearl install vim-rails
Voila', your new vim plugin is ready to be used!
This approach is particularly useful whenever you do not need to specify any pearl config to "enrich" the third-party project inside the Pearl environment.
A Pearl repository is just a git repository containing a file located in pearl-config/pearl.conf
with a list of packages. For instance, the OPH repository is available
here.
In order to use the new repository (i.e. "https://github.com/myrepo/pearl-repo.git"),
update the pearl.conf file by adding the following line:
PEARL_REPOS += ("https://github.com/myrepo/pearl-repo.git")
Q: What should I do if I accidentally removed files/packages in
$PEARL_HOME?
A: You can recover the structure of the
$PEARL_HOMEby running:
$> pearl init
The command will create all the essential directories and symlinks in
$PEARL_HOME. It is harmless to run theinitcommand multiple times since it is idempotent.
Q: Why I can no longer update/remove a package?
A: This is probably because either one of the hook functions is failing or the package content is corrupted. You can forcely remove the package:
$> pearl remove <packagename>
which bypass hook functions that are failing. If that does not even work, you can delete a package by simply removing its directory:
$> rm -rf $PEARL_HOME/packages/pearl/<packagename>
After that, you can reinstall the package again. The Pearl packages contain a dedicated directory
varfor storing data needed for the package itself. Thevardata are always managed by the package and they never gets deleted by Pearl during the package removal. If you want to delete the content invarpackage:
$> rm -rf $PEARL_HOME/var/pearl/<packagename>
Q: Why are not package's environment variables/functions visible in my current shell after installing/updating the package?
A: After package install/update, the variables or functions related to the current shell and defined in
pearl-config/config.*may not be available because a reload of Pearl configuration file is required. You can fix this by simply run the function:
pearl-source
which reloads the configuration. The use of such function is not always required but depends whether the variables/functions involve the current shell where the package
install/updateoccurred (i.e. a new variable defined inconfig.shand the current shell is a bash or zsh). Alternatively, user can always create a new shell and the package resources will be available as expected.
Q: Why Do I get the following error:
Error on executing 'post_install' hook. Rolling back...
A: This occurs when the
post_installhook function fails. Pearl will attempt to roll back and force a removal of the package. In this way you can attempt to install the package again once the hook function gets fixed.
You could help improving Pearl and the OPH in the following ways: