#+TITLE: Carbs Packaging Tools
#+SUBTITLE: User Manual
#+AUTHOR: Cem Keylan
#+EMAIL: cem@ckyln.com
#+TEXINFO_FILENAME: cpt.info
#+TEXINFO_DIR_CATEGORY: Development
#+TEXINFO_DIR_TITLE: Carbs Packaging Tools: (cpt)
#+TEXINFO_DIR_DESC: Carbs Package Management Library
#+DATE: {{{modification-time(%B %d\, %Y, 1)}}}

This is a reference document containing both the user-guide and the development
manual for *Carbs Packaging Tools*. For development logs see [[https://git.carbslinux.org/cpt][the git repository]].

* Table of Contents                                            :TOC:noexport:
- [[#copying][Copying]]
- [[#preface][Preface]]
- [[#usage][Usage]]
  - [[#cpt-alternatives][cpt-alternatives]]
  - [[#cpt-build][cpt-build]]
  - [[#cpt-checksum][cpt-checksum]]
  - [[#cpt-download][cpt-download]]
  - [[#cpt-install][cpt-install]]
  - [[#cpt-list][cpt-list]]
  - [[#cpt-remove][cpt-remove]]
  - [[#cpt-search][cpt-search]]
  - [[#cpt-update][cpt-update]]
  - [[#global-flags][Global Flags]]
- [[#environment-variables][Environment Variables]]
  - [[#cpt_path][=CPT_PATH=]]
  - [[#cpt_compress][=CPT_COMPRESS=]]
  - [[#cpt_force][=CPT_FORCE=]]
  - [[#cpt_pid][=CPT_PID=]]
- [[#hooks][Hooks]]
  - [[#editing-the-build-file-during-pre-build][Editing the =build= file during pre-build]]
- [[#packaging-system][Packaging System]]
  - [[#build][=build=]]
  - [[#sources][=sources=]]
  - [[#checksums][=checksums=]]
  - [[#version][=version=]]
  - [[#depends][=depends=]]
  - [[#post-install][=post-install=]]
  - [[#message][=message=]]
  - [[#test][=test=]]
- [[#rsync-repositories][Rsync Repositories]]
  - [[#setting-up-an-rsync-repository][Setting up an Rsync repository]]
- [[#cpt-library][CPT Library]]
  - [[#calling-the-library][Calling the library]]
  - [[#option-parsing][Option parsing]]
  - [[#message-functions][Message functions]]
  - [[#text-functions][Text functions]]
  - [[#system-functions][System Functions]]

* Copying
:PROPERTIES:
:COPYING:  t
:END:

Copyright \copy 2020 Cem Keylan

#+begin_quote
Permission is granted to copy, distribute and/or modify this document under the
terms of the GNU Free Documentation License, Version 1.3 or any later version
published by the Free Software Foundation; with no Invariant Sections, with no
Front-Cover Texts and no Back-Cover Texts. A copy of the license is included in
the section entitled "GNU Free Documentation License."
#+end_quote

* Preface
:PROPERTIES:
:DESCRIPTION: Introduction to Carbs Packaging Tools
:END:

Carbs Linux uses its own package management toolchain named =cpt= which was
initially forked from the [[https://github.com/kisslinux/kiss][kiss]] package manager. Unlike =kiss=, however, its main
goal is being easily extendable. Instead of being a single file package manager,
it revolves around the shell library =cpt-lib=, and many tools that wrap around
it. This document aims to document both the usage of the distributed tools and
document the library functions.

* Usage
:PROPERTIES:
:DESCRIPTION: Basic usage of Carbs Packaging Tools
:END:

=cpt= is formed of many tools combined in a single environment, similar to
=git=. When you run =cpt= without any arguments, it will show all available
tools and their explanations. Here is an example call with extra scripts on my
system:

#+BEGIN_EXAMPLE
  -> Carbs Packaging Tool
  -> add               Commit the current directory as a new package
  -> alternatives      List and swap to alternatives
  -> build             Build a package
  -> bump              Commit the current directory as a version bump
  -> cargo-urlgen      Create static cargo sources for Rust packages
  -> cargolock-urlgen  Convert the given Cargo.lock file to sources
  -> cat               Concatanate package files in the installed package database
  -> changelog         Print the git log of the specific package
  -> chbuild           Create/destroy temporary chroots
  -> checkmissing      Verify package manifests
  -> checksum          Generate checksums
  -> chroot            Enter a chroot
  -> commit            Commit a package without the prefix of 'package:'
  -> depends           Display a package's dependencies
  -> download          Download sources for the given package
  -> exec              Execute a command inside the alternatives system
  -> export            Turn an installed package into a CPT tarball
  -> fork              Fork a package to the current directory
  -> getchoice         Prints the full path to a file in the alternatives system.
  -> install           Install a package
  -> link              Link a forked package's files to the other repository
  -> list              List installed packages
  -> maintainer        Find the maintainer of a package
  -> manifest          Display all files owned by a package
  -> manifest-tree     Display all files owned by a package with a tree view
  -> new               Create a boilerplate CPT package
  -> orphans           List orphaned packages
  -> owns              Check which package owns a file
  -> rel               Bump the release number of a package
  -> remove            Remove a package
  -> repodepends       Display a package's dependencies in the repository
  -> reporevdepends    Display packages on the repository which depend on package
  -> reset             Remove all packages except for the base
  -> revdepends        Display packages which depend on package
  -> search            Search for a package
  -> size              Show the size on disk for a package
  -> source            Extract sources of a given package to the current directory
  -> update            Check for updates
#+END_EXAMPLE

** cpt-alternatives
:PROPERTIES:
:DESCRIPTION: List and swap to alternatives
:END:

You can list and swap to alternatives using =cpt-alternatives=, or
=cpt a= for short. When run without alternatives, it will list
alternatives. It can read from standard input if =-= is given as an
argument.

*Examples*

1. List alternatives.

#+BEGIN_EXAMPLE
  $ cpt-alternatives
  ncurses /usr/bin/clear
  ncurses /usr/bin/reset
#+END_EXAMPLE

2. Swap to =clear= from =ncurses=.

#+BEGIN_EXAMPLE
  $ cpt-alternatives ncurses /usr/bin/clear
  -> Swapping '/usr/bin/clear' from 'busybox' to 'ncurses'
#+END_EXAMPLE

3. Swap in bulk (all of =sbase=).

#+BEGIN_EXAMPLE
  $ cpt a | grep ^sbase | cpt a -
#+END_EXAMPLE

** cpt-build
:PROPERTIES:
:DESCRIPTION: Build a package
:END:

=cpt-build= will build given packages and their dependencies. If multiple
packages are specified, it will ask to install the packages as well.

| Flags          | Explanation  |
|----------------+--------------|
| =-t=, =--test= | Run tests    |

** cpt-checksum
:PROPERTIES:
:DESCRIPTION: Generate checksums
:END:

=cpt-checksum= will generate a =checksums= file from the package's sources.

** cpt-download
:PROPERTIES:
:DESCRIPTION: Download sources for the given package
:END:

=cpt-download= will download the sources of a package.

** cpt-install
:PROPERTIES:
:DESCRIPTION: Install a package
:END:

=cpt-install= will install given packages.

** cpt-list
:PROPERTIES:
:DESCRIPTION: List installed packages
:END:

When called without arguments, =cpt-list= will print all installed
packages. You can add package names as arguments to check whether they are
installed or not. In success, =cpt-list= will exit with status 0 if all
given packages are installed, it will return 1 if any of the given packages
aren't installed.

| Flags             | Explanation                            |
|-------------------+----------------------------------------|
| =-c=, =--current= | Use the current directory as a package |

** cpt-remove
:PROPERTIES:
:DESCRIPTION: Remove a package
:END:

=cpt-remove= will remove given packages.

** cpt-search
:PROPERTIES:
:DESCRIPTION: Search for a package
:END:

=cpt-search= will search for packages, it accepts regular expressions as well.

| Flags            | Explanation                               |
|------------------+-------------------------------------------|
| =-s=, =--single= | Only show the first instance of a package |


#+BEGIN_EXAMPLE
  $ cpt-search 'alsa-*'
  /var/db/cpt/repo/extra/alsa-lib
  /var/db/cpt/repo/extra/alsa-utils
  /var/db/cpt/installed/alsa-lib
  /var/db/cpt/installed/alsa-utils

  $ cpt-search emacs
  /home/cem/repos/main/community/emacs
  /home/cem/repos/kiss-community/community/emacs
  /var/db/cpt/installed/emacs

  $ cpt-search --single emacs
  /home/cem/repos/main/community/emacs
#+END_EXAMPLE

** cpt-update
:PROPERTIES:
:DESCRIPTION: Check for updates
:END:

=cpt-update= will update the packages on your system. It fetches remote
repositories, and builds, and installs packages that have versions different
from the ones installed on the system. It doesn't check if the version string
is actually higher, it only checks whether they differ.

| Flags                | Explanation                          |
|----------------------+--------------------------------------|
| =-d=, =--download=   | Only download updatable packages     |
| =-n=, =--no-fetch=   | Do not update remote repositories    |
| =-o=, =--only-fetch= | Only fetch the repositories and exit |

** Global Flags
:PROPERTIES:
:DESCRIPTION: Flags that work globally on some cpt utilities
:END:

| Flags               | Explanation                      |
|---------------------+----------------------------------|
| =-f=, =--force=     | Force operation, [[=CPT_FORCE=][See =CPT_FORCE=]] |
| =-y=, =--no-prompt= | Do not prompt for confirmation   |
| =-root CPT_ROOT=    | Use an alternate root directory  |
| =-h=, =--help=      | Show this help message           |
| =-v=, =--version=   | Print version information        |

* Environment Variables
:PROPERTIES:
:DESCRIPTION: Change the behaviour of cpt through environment configuration
:END:

Since there is no configuration file for cpt, the package manager is configured
through environment variables. These can be set per operation, or be set to your
shell configuration or =~/.profile=. Here are the environment variables that
alter the behaviour of =cpt=:

| ENVIRONMENT VARIABLE | Effects                                                                       |
|----------------------+-------------------------------------------------------------------------------|
| =CPT_PATH=           | Set the locations of your repositories. It is similar to the =PATH= variable. |
| =XDG_CACHE_HOME=     | Unless this is set, the =~/.cache= directory will be used instead.            |
| =CPT_CACHE=          | The cache directory for =cpt=. Default: =$XDG_CACHE_HOME/cpt=                 |
| =CPT_CHOICE=         | If this is set to 0, a package installation will be aborted on conflicts.     |
| =CPT_COMPRESS=       | Program used to compress package tarballs.                                    |
| =CPT_DEBUG=          | If set to 1, temporary directories will not be removed after the operation.   |
| =CPT_FETCH=          | If set to 0, =cpt-update= will not fetch repositories.                        |
| =CPT_FORCE=          | Force operation.                                                              |
| =CPT_HOOK=           | Location for the hook file.                                                   |
| =CPT_KEEPLOG=        | If set to 1, cpt will keep logs regardless of operation success.              |
| =CPT_PID=            | Set the temporary build directory name.                                       |
| =CPT_PROMPT=         | If set to 0, =cpt= will not prompt you for anything.                          |
| =CPT_ROOT=           | If this variable is set, =cpt= will assume this as the system root.           |
| =CPT_TEST=           | If set to 1, =cpt-build= will run tests whenever available.                   |
| =CPT_TMPDIR=         | The directory to create the temporary directories.                            |

** =CPT_PATH=
:PROPERTIES:
:DESCRIPTION: Set the locations of your repositories
:END:

Similar to the =PATH= variable, =cpt= find repositories from the =CPT_PATH=
variable. Here is an example:

#+begin_src sh
  CPT_PATH=$HOME/repos/repo1:$HOME/repos/repo2:$HOME/repos/repo3
#+end_src

This is a simplistic and a structured example for repository locations, but it
doesn't necessarily need to be as tidy as the example above. Here is an example
for something a little more complex.

#+begin_src sh
  CPT_PATH=$HOME/repos/overrides:/var/db/cpt/repo/core:/var/db/cpt/repo/extra:$HOME/repos/personal
#+end_src

This example brings us to the next section of this document.

*** Repository preferences
:PROPERTIES:
:DESCRIPTION: Prioritise package repositories
:END:

When you are using multiple repositories from multiple vendors, you will find
out that some repositories have the same packages. =cpt= doesn't care about
conflicting packages. If you want to build a package that exists on multiple
repositories, =cpt= will build the first matching package. This means that if
=grep= package (for the sake of an example) exists on both
=$HOME/repos/personal= and =$HOME/repos/carbs/extra=, and you want
to install from your personal repository, you must set =CPT_PATH= so that your
personal repository is listed before the =extra= repository.

#+begin_src sh
  CPT_PATH=$HOME/repos/personal:$HOME/repos/carbs/extra
#+end_src

*** Setting the =CPT_PATH=
:PROPERTIES:
:DESCRIPTION: Set the value of CPT_PATH on your shell configuration
:END:

You can set the =CPT_PATH= variable on your shell configuration or your
=.profile= file in a way that is easy to read.

The below example sets =CPT_PATH= in a way that is easy to understand which
repository comes first:

#+begin_src sh
  CPT_PATH=$HOME/repos/overrides
  CPT_PATH=$CPT_PATH:$HOME/repos/carbs/core
  CPT_PATH=$CPT_PATH:$HOME/repos/carbs/extra
  CPT_PATH=$CPT_PATH:$HOME/repos/carbs/xorg
  CPT_PATH=$CPT_PATH:$HOME/repos/personal
  export CPT_PATH
#+end_src

** =CPT_COMPRESS=
:PROPERTIES:
:DESCRIPTION: Compression tool to use in cpt
:END:

When setting the =CPT_COMPRESS= value, you should set the name of the default
suffixes for the program. Available values are:

- =gz=
- =zst=
- =bz2=
- =xz=

Defaults to =gz=.

** =CPT_FORCE=
:PROPERTIES:
:DESCRIPTION: Force operations on cpt
:END:

If this is set to 1, some of the =cpt= tools will continue regardless of
errors or skip certain checks. Here are some examples:

- =cpt-install= will install a package without verifying its manifest.
- =cpt-install= will install a package even when there are missing dependencies.
- =cpt-remove= will remove packages even when there are other packages that
  depend on the current package.

Defaults to 0.

** =CPT_PID=
:PROPERTIES:
:DESCRIPTION: Set reproducible temporary directories
:END:

If this variable is set, the temporary files will be created with this variable
as the suffix, instead of the PID of the =cpt= process. The advantage is that
you can know exactly where the build directory is located, while the
disadvantage is that there will be issues with multiple operations at the same
time. So the best way to use this variable is during one-time =cpt= calls.

#+BEGIN_EXAMPLE
  CPT_PID=mesa cpt b mesa
#+END_EXAMPLE

By running the above, you will know that the created build directories will end
with the =*-mesa= suffix.

* Hooks
:PROPERTIES:
:DESCRIPTION: Use hooks to customize the package manager operations
:END:

Hooks can be used in order to change the runtime behaviour of the package manager.
There are a variety of package hooks, mostly self explanatory:

- pre-build
- post-build
- build-fail
- pre-test
- test-fail
- pre-install
- post-install
- pre-remove
- post-remove
- pre-fetch
- post-fetch
- post-package

In order to use hooks, you will need to set the =CPT_HOOK= variable pointing to
your hook file. Your hook file *MUST* be a POSIX shell script as its contents
are sourced by the package manager.

The hook is given 3 variables when it is executed. Those are:

| Variable | Explanation                                                  |
|----------+--------------------------------------------------------------|
| =$TYPE=  | The type of the hook, (=pre-build=, =post-build=, etc.)      |
| =$PKG=   | The package that =cpt= is currently working on. Can be null. |
| =$DEST=  | The destination of the operation. Can be null.               |

** Editing the =build= file during pre-build
:PROPERTIES:
:DESCRIPTION: Modify a package build with your hooks
:END:

You can edit the =build= file during pre-build. The file is copied from the
repository to the build directory named as =.build.cpt=. You can use =sed= or
any other tool to edit the build file. After the build is complete, a =diff=
file will be placed to the package database named as =build.diff=. Here is an
example =build= file manipulation during the pre-build hook.

#+BEGIN_SRC sh
  cat <<EOF> .build.cpt
  #!/bin/sh -e

  for patch in bash50-0??; do
      patch -p0 < "\$patch"
  done

  export LDFLAGS=-static

  ./configure \
      --prefix=/usr \
      --without-bash-malloc \
      --disable-nls

  export MAKEFLAGS="TERMCAP_LIB=/usr/lib/libncursesw.a $MAKEFLAGS"

  make
  make DESTDIR="\$1" install

  ln -s bash "\$1/usr/bin/sh"
  EOF
#+END_SRC

* Packaging System
:PROPERTIES:
:DESCRIPTION: More detail on creating packages
:END:

A package is formed of several files, these are:

- [[=build=]]
- [[=sources=]]
- [[=checksums=]]
- [[=version=]]
- [[=depends=]]
- [[=post-install=]]
- [[=message=]]
- [[=test=]]

Any other file can be added to the package directory at the discretion of the
package maintainer. Everything in the package directory will also be added to the
package database that is located on =/var/db/cpt/installed=. These can be
patches, configuration files, etc.

** =build=
:PROPERTIES:
:DESCRIPTION: The build script
:END:

Typically =build= files are shell scripts that run commands to prepare the source
code to be installed on the target system. Even though we will be assuming that
the =build= file is a POSIX shell script (for portability's sake), =build=
files can be any executable program from binary programs to =perl= scripts.

The contents of a build script do not need to follow a certain rule for the
package manager, except for the fact that the user needs the permission to
execute the file.

An important advice is to append an '-e' to the shebang (#!/bin/sh -e) so that
the build script exits on compilation error.

Build is run with three arguments (=$#=)

- Location of the package directory (DESTDIR)
- Package version
- System architecture

** =sources=
:PROPERTIES:
:DESCRIPTION: The file containing package sources
:END:

=sources= file is a list of files and sources that will be put to the build
directory during the build process. Those can be remote sources (such as tarballs),
git repositories, and files that reside on the package directory.

The syntax is pretty simple for the =soures= file; =src dest=. The =dest=
parameter is optional. It is the directory that the source will be placed in.
Here is the =sources= file for the =gst-plugins= package:

#+BEGIN_EXAMPLE
  https://gstreamer.freedesktop.org/src/gst-plugins-good/gst-plugins-good-1.16.2.tar.xz good
  https://gstreamer.freedesktop.org/src/gst-plugins-bad/gst-plugins-bad-1.16.2.tar.xz   bad
  https://gstreamer.freedesktop.org/src/gst-plugins-ugly/gst-plugins-ugly-1.16.2.tar.xz ugly
  https://gstreamer.freedesktop.org/src/gst-libav/gst-libav-1.16.2.tar.xz               libav
#+END_EXAMPLE

This file is read from the package manager as space seperated. Files that begin
with a =#= comment are ignored. The first value points to the location of the
source.

If it starts with a protcol url, (such as ftp:// http:// https://) it will be
downloaded with =curl=.

If the source is a git repository, it shall be prefixed with a =git+= git(1) will
be used to do a shallow clone of the repository. If the commit is suffixed by a
history pointer, git will checkout the relevant revision. So,

- =git+git://example.com/pub/repo@v1.2.3= :: will checkout the tag named "v1.2.3"
- =git+git://example.com/pub/repo#development= :: will checkout the branch named "development"
- =git+git://example.com/pub/repo#1a314s87= :: will checkout the commit named "1a314s87"

Other files are assumed to be residing in the package directory. They should be
added with their paths relative to the package directory.

** =checksums=
:PROPERTIES:
:DESCRIPTION: The file containing sha256sum of the sources
:END:

checksums file is generated by the =cpt c pkg= command. It is generated
according to the order of the sources file. That's why you shouldn't be editing
it manually. The checksums file is created with the digests of the files using
the sha256 algorithm.

** =version=
:PROPERTIES:
:DESCRIPTION: The file containing the version and the release numbers of a package
:END:

The version file includes the version of the software and the release number of
of the package on a space seperated format. The contents of the file should look
like below.

#+BEGIN_EXAMPLE
  1.3.2 1
#+END_EXAMPLE

** =depends=
:PROPERTIES:
:DESCRIPTION: The file containing the dependencies of a package
:END:

This is a list of dependencies that must be installed before a package build. You
can append "make" after a dependency to mark a package is only required during
the build process of a package. Packages marked as a make dependency can be
removed after the build. There are also "test" dependencies. These dependencies
are only installed if either the =CPT_TEST= is set to 1, or the build is run
with the =-t= or =--test= options. So, a package package could have
the following =depends= file:

#+BEGIN_EXAMPLE
  linux-headers make
  python        test
  zlib
#+END_EXAMPLE

** =post-install=
:PROPERTIES:
:DESCRIPTION: The post-installation script
:END:

=post-install= files have the same requirements as the build script. They
will be run after the package is installed as root (or as the user if the user
has write permissions on =CPT_ROOT=).

** =message=
:PROPERTIES:
:DESCRIPTION: The post-installation message to be displayed
:END:

This plaintext file will be outputted with =cat= after every package is
installed.

** =test=
:PROPERTIES:
:DESCRIPTION: The test script for a package
:END:

Test files are mainly for the repository maintainer to test the packages, and
will only run if the user has the =CPT_TEST= variable set, or the build is
run with the =-t= or =--test= options. This script is run on the
build directory. It is run right after the build script is finished.

* Rsync Repositories
:PROPERTIES:
:DESCRIPTION: Information on using or creating rsync repositories
:END:

Rsync repositories are simple to serve and simple to use. In the repository
directory, there needs to be a =.rsync= file that points to the remote of the
repository. This is used in order to fetch changes from the upstream. =.rsync=
file looks like this for the core repository:

#+BEGIN_EXAMPLE
  rsync://carbslinux.org/repo/core
#+END_EXAMPLE

Rsync repositories have some few distinctions when it comes to fetching them.
They can be either synced individually or as a "root". There are 2 important
files, those are =.rsync= and =.rsync_root=. Here is the Carbs Linux
rsync repository structure.

#+BEGIN_EXAMPLE
             /
     -----------------
    |                |
  .rsync           core/
            ----------------
            |              |
          .rsync      .rsync_root
#+END_EXAMPLE

Unlike git repositories, they don't have a defined "root" directory. This is
both an advantage and a disadvantage. This way, we can sync individual
repositories, but that also means we need extra files to define root directories
and repository locations. Here is the content for each of these files:

#+BEGIN_EXAMPLE
  /.rsync:           rsync://carbslinux.org/repo
  /core/.rsync:      rsync://carbslinux.org/repo/core
  /core/.rsync_root: ..
#+END_EXAMPLE

The =.rsync_root= file on the core repository points to the upper directory.
If a =.rsync= file exists on the upper directory, this means that is the whole
repository and will sync the entire repository instead of each individual repository.

If the upper directory doesn't have this =.rsync= file, this means that this
is an individual repository, and the package manager will fetch accordingly.

** Setting up an Rsync repository
:PROPERTIES:
:DESCRIPTION: Set up a repository for distribution
:END:

Carbs Linux repositories automatically sync from the git repostitories and serve
it through the rsync daemon. Here is a sample shell script that I use in order to
sync repositories. Feel free to customize for your own use.

#+BEGIN_SRC sh
  #!/bin/sh
  HOSTNAME="rsync://carbslinux.org/repo"
  GITDIR="/pub/git/repo"
  SHAREDIR="/pub/share/repo"
  git -C "$GITDIR" pull

  rsync -avcC --delete --include=core --exclude=.rsync,.rsync_root "$GITDIR/." "$SHAREDIR"

  printf '%s\n' "$HOSTNAME" > "$GITDIR/.rsync"
  for dir in "$GITDIR/"*; do
      [ -d "$dir" ] || continue
      [ -f "$dir/.rsync" ] ||
      printf '%s/%s\n' "$HOSTNAME" "${dir##*/}" > "$dir/.rsync"
      printf '..\n' > "$dir/.rsync_root"
  done
#+END_SRC

You can then create an *rsync* user for serving the repositories.

#+BEGIN_EXAMPLE
  $ adduser -SD rsync
#+END_EXAMPLE

Create =/etc/rsyncd.conf= and a service configuration as well.

#+BEGIN_EXAMPLE
  uid = rsync
  gid = rsync
  address = example.com
  max connections = 10
  use chroot = yes

  [repo]
      path = /pub/share/repo
      comment = My repository
#+END_EXAMPLE

Create a service file at =/etc/sv/rsync/run= (runit):

#+BEGIN_SRC sh
  #!/bin/sh -e
  exec rsync --daemon --no-detach
#+END_SRC

* CPT Library
:PROPERTIES:
:DESCRIPTION: Documentation of the Library
:END:

=cpt-lib= is the library of Carbs Packaging Tools which can be used to extend
the functionality of the package manager. This is the API documentation of the
package manager library.

** Calling the library
:PROPERTIES:
:DESCRIPTION: Including the library on your code
:END:

You can call the library on your scripts by adding the following line to your
files:

#+begin_src sh
  #!/bin/sh -e
  . cpt-lib
#+end_src

This will load the library inside your script, and will set some environment
variables that are used inside the package manager.

** Option parsing
:PROPERTIES:
:DESCRIPTION: Easy way of parsing options with cpt-lib
:END:

=cpt-lib= includes a POSIX-shell option parser inside named =getoptions=. You
can see its own [[https://github.com/ko1nksm/getoptions/blob/v2.0.1/README.md][documentation]] for writing an option parser. The built-in version
of the =getoptions= library is 2.0.1 and there are no plans for updating it
apart from bug fixes.

*** Defining a parser
:PROPERTIES:
:DESCRIPTION: Correct way of using getoptions
:END:

Some functions are called and set automatically when you call =cpt-lib=, so you
shouldn't define the option parser after calling the library, as some of the
variables will already be set.

If the function =parser_definition()= as defined when =cpt-lib= is called,
cpt-lib will handle the option parsing itself by calling =getoptions=
inside. Here is the proper way of doing it.

#+begin_src sh
  #!/bin/sh -e

  parser_definition() {
      # The rest arguments MUST be defined as 'REST'
      setup REST help:usage -- "usage: ${0##*/} [options] [pkg...]"
      msg                   -- '' 'Options:'
      flag CPT_TEST -t export:1 init:@export -- "Enable tests"

      global_options
  }

  . cpt-lib
#+end_src

*** =global_options()=
:PROPERTIES:
:DESCRIPTION: Convenience function for defining common flags
:END:

The =global_options()= function is a simple convenience call to include flags
that can be used inside most =cpt= tools. It defines the following flags:

| Flag | Long Option | Calls        |
|------+-------------+--------------|
| -f   | --force     | =CPT_FORCE=  |
| -y   | --no-prompt | =CPT_PROMPT= |
|      | --root      | =CPT_ROOT=   |
| -h   | --help      | =usage()=    |
| -v   | --version   | =version()=  |

** Message functions
:PROPERTIES:
:DESCRIPTION: Communicate to users
:END:
=cpt= has various functions to print information to users.
*** =out()=
:PROPERTIES:
:DESCRIPTION: Print a message as-is
:END:

=out()= is a really simple function that prints messages to the standard
output. It prints every argument with a newline. It is not meant to communicate
with the user, it just exists to have a simple function to interact with other
functions.

#+begin_src sh
  $ out "This is an example call" "How are you?"
  This is an example call
  How are you?
#+end_src

*** =log()=
:PROPERTIES:
:DESCRIPTION: Print a message prettily
:END:

=log()= is the most commonly used message function in the package manager. It is
used to pretty print messages with visual cues, so it is easier to read and
understand for the users. It changes message output for each argument it
receives (takes up to three arguments).

- If it takes a single argument, it prints a yellow leading arrow followed by
  colorless text.
- If it takes two arguments, it prints a yellow leading arrow followed by the
  first argument (colored blue), and then followed by colorless second argument.
- If it takes three arguments, instead of a yellow arrow, it prints the third
  argument in yellow, followed by the same two arguments as above.

*** =die()=
:PROPERTIES:
:DESCRIPTION: Print a message and exit with error
:END:

=die()= wraps the =log()= function and exits with an error (1). It takes one or
two arguments, which are sent to the =log()= function. The third argument for
=log()= is set as =!>=.

*** =warn()=
:PROPERTIES:
:DESCRIPTION: Print a warning message
:END:

=warn()= is another function that wraps =log()=. In place of the third argument,
it uses the word =WARNING=.

*** =prompt()=
:PROPERTIES:
:DESCRIPTION: Ask the user whether they want to continue
:END:

=prompt()= is an interactive function that waits for user input to continue.
It takes a single argument string to print a message, and then asks the user
whether they want to continue or not. Prompts can be disabled by the user if
they use a flag to disable them or set =CPT_PROMPT= to 0.

** Text functions
:PROPERTIES:
:DESCRIPTION: Manipulate or check text
:END:

Following functions are used to manipulate, check, or interact with text.

*** =contains()=
:PROPERTIES:
:DESCRIPTION: Check if a "string list" contains a word
:END:

=contains= function can be used to check whether a list variable contains a
given string. If the string is inside the list, it will return 0, otherwise 1.

#+begin_src sh
  # Usage
  contains "$LIST" foo

  contains "foo bar" foo  # Returns 0
  contains "foo bar" baz  # Returns 1
#+end_src

*** =regesc()=
:PROPERTIES:
:DESCRIPTION: Escape regular expression characters
:END:

=regesc()= can be used to escape regular expression characters that are defined
in POSIX BRE. Those characters are, =$=, =.=, =*=, =[=, =\\=, and =^=.

#+begin_src sh
  regesc '^[$\'  # Returns \^\[\$\\
#+end_src

*** =pop()=
:PROPERTIES:
:DESCRIPTION: Remove an item from a string list
:END:

=pop()= can be used to remove a word from a "string list" without a =sed=
call. Word splitting is intentional when using this function.

#+begin_src sh
  # Usage
  pop foo from $LIST

  pop foo from foo baz bar # Returns baz bar
#+end_src

** System Functions
*** =as_root()=
:PROPERTIES:
:DESCRIPTION: Run a command as the root user
:END:

=as_root()= calls the rest of the arguments as a different user. Unless a =user=
environment variable is set, it will call the following arguments as the root
user. It supports the following programs for privilege escalation with the
following order:

1. =sudo=
2. =doas=
3. =su=