Ubuntu Unleashed 2017 Edition (2017)

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To create a new repository, create an empty project directory:

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matthew@seymour:~$ hg init your_project_name

Then add your files to the directory. cd into the directory if you are not already in it, and enter the following:

matthew@seymour:~$ hg add

To check in code the first time or after you have made changes, use the -m flag to add a note, which is a good idea so that others know what the commit contains:

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matthew@seymour:~$ hg commit -m 'First commit.'

In Mercurial, a commit does not change the remote files, it only commits the change to your local copy. If you want others to see your changes, you must push the changes to them:

matthew@seymour:~$ hg push

To update the source code in your local repository from the main repository to make sure you have all the latest changes to the code from other developers, use this:

matthew@seymour:~$ hg update

Many open-source projects that use Mercurial host their code using Bitbucket. You can find it at http://bitbucket.org.

Introduction to Opportunistic Development

You have an idea for a program that will save time by automating a repetitive task. You plan for it to have a pretty GUI, and you think there are probably others out there who would like to use the tool after it is written. The problem is that you work full time, have a family, and already have a ton of side projects that do not get enough attention. You are either not able or not willing to sit down and study how Ubuntu packages programs to get them into the official software repositories. (If you are, see the links in the “References” section.)

It used to be that you had one simple choice at this juncture: Write the program and put it on a website for others to find—and hope that maybe someone would find it useful, make a DEB package, and upload it into either the Debian or Ubuntu repositories. That is no longer the only option if your goal is simply to write your tool and make the software available to Ubuntu users. Now, you need to be technically proficient at writing whatever code you want to write, and you need to be able to understand complex systems, but Ubuntu is lowering the complexity for getting that code written and making it available to the wider community. This enables developers who want only to scratch that one itch to do so without reading tons of documentation about tools they expect to use rarely or only once.

Launchpad

To get started, you need to sign up for an account on Launchpad (see Figure 39.1). Launchpad is an infrastructure created to simplify communication, collaboration, and processes within software development. It was developed and is supported by Canonical, the company that supports the Ubuntu community, but it is used by many software projects, including several that are not a part of the Ubuntu community.

FIGURE 39.1 Launchpad is the place to start for development in Ubuntu.

Launchpad is where most Ubuntu development takes place, although some has moved to Git. It integrates Bazaar, the version control system introduced earlier, to make keeping track of changes to software code much simpler and permit those changes to be reverted when necessary while tracking who is performing the actions. Launchpad also incorporates Soyuz, which is a distribution and archive management software that handles the automatic package builds within Launchpad.

For developers using Launchpad, this means that the process became a bit simpler. They can concentrate on writing and editing their code and let Launchpad deal with keeping track of the changes and creating their packages. This is useful for active developers who write and maintain big projects that need source code version control and so on. It also hosts bug reporting and tracking, mailing lists, software interface translation, and much more. Most of this is beyond the scope of this chapter but of great interest to the serious developer.

What is of interest to us is that registered Launchpad users can create a personal package archive (PPA). This is a much simpler way to make programs available. Anyone with a PPA can upload source code to be built in to packages. Those packages will then be made available in an apt repository that may be added to any Ubuntu user’s list of source repositories and downloaded or removed using any of the standard package management tools in Ubuntu, such as apt, Ubuntu Software Center, and Synaptic. Instructions are included on the web page for each Launchpad PPA, describing how to add that repository, making this an easy method to share software that may be added and removed by even the most nontechnical end user. Figure 39.2 shows the PPA for the stable version of Google Chromium.

FIGURE 39.2 A Launchpad PPA for the stable version of Google Chromium.

Ubuntu Make

Ubuntu Make is a command-line tool that sets up your system for development use quickly and easily. It allows you to download the latest version of popular developer tools and their dependencies, enable multi-arch, and more. Install ubuntu-make to get started. Then, run commands like this to install tools:

matthew@seymour:~$ umake android

In this example, you will be prompted to accept the install path and Google license, and then Ubuntu Make will download and install Android Studio and the latest SDK, configure everything, and if you are running on a 64-bit platform, even add a Unity launcher icon.

See https://wiki.ubuntu.com/ubuntu-make to learn more about the packages available and get started.

Creating Snap Packages

One of the more exciting opportunities for developers is the new snap package format. Along with the basic installation and other details given in Chapter 9, “Managing Software,” snap packaging also allows single packaged application to be used across multiple Linux distributions. Although snap packages are not expected to replace traditional packaging formats like DEBs, which we cover in Chapter 40, “Helping with Ubuntu Development,” it is reasonable to expect snaps to find wide use for applications provided by third-party vendors like Mozilla, who are already committed to using it for their Firefox web browser, and for applications intended for use on devices like phones, routers, switches, and the new category of IoT (internet of things) devices (see https://en.wikipedia.org/wiki/Internet_of_things). For desktop applications, snap packaging enables the developer to submit free or even for-payment apps for review and inclusion in the Ubuntu Software application (see Chapter 9, “Managing Software”).

The tool used to create snap packages is Snapcraft, available from http://snapcraft.io/. Snapcraft is designed to take your already-created application and bundle it with any and all dependencies for easy installation and updating.

Another helpful community project related to snap packaging is Snappy Playpen at https://github.com/ubuntu/snappy-playpen, which exists to share knowledge and best practices about snap packaging while helping test the packages that community members and others create.

Bikeshed and Other Tools

Bikeshed was started by Dustin Kirkland in September 2010 as a project to package a series of tools he wrote to scratch some personal itches that he had as an Ubuntu developer working on Canonical’s Ubuntu Server Team or that he thought would be useful to others. Every good developer, systems administrator, and DevOps guru eventually writes scripts to perform specific tasks they find useful. This project began when Dustin gathered his scripts together and made them accessible to the world. The wider Ubuntu community is invited to give suggestions or submit patches to make them better. The project describes itself as “a collection of random useful tools and utilities that either do not quite fit anywhere else, or have not yet been accepted by a more appropriate project. Think of this package as an ‘orphanage,’ where tools live until they are adopted by loving, accepting parents.” The slogan for Bikeshed on the Launchpad project page is “While others debate where some tool should go, we put it in the Bikeshed.”

To give credit where credit is due, much of the content in this section comes, with permission, from Dustin’s blog at http://blog.dustinkirkland.com, from direct communication with him, or from the tool man pages. Dustin also wrote Byobu, a tool that is covered at the end of Chapter 12, “Command-Line Master Class Part 2,” and which contains some of the tools that have graduated from Bikeshed.

The first set of tools in this section are available by installing the bikeshed package from the Ubuntu repositories. Bikeshed sometimes works as an incubator, housing specific tools until they are ready to stand alone as a separate package or until they are accepted into an existing package. All the tools run from the command line, and most have useful man pages. (Others are still being written.)

The current contents of Bikeshed are as follows:

apply-patch—wraps the patch utility and makes it a little easier to use by automatically detecting the patch strip level.

bch—determines the files that have been modified in the current Bazaar (bzr) tree, opens debian/changelog for editing, uses dch, and appends a changelog entry for the current list of modified files.

bzrp—is the same as bzr, except that output is piped to a pager to make reading easier.

col1—splits and prints a given column, where the column to print is the name of the script program you are running (col1 to col9). col2 to col9 are symlinks to col1; their behavior simply changes based on the name called. For example, instead of using awk '{print $5}' you can use col5.

cloud-sandbox—launches a cloud instance and connects directly to it using ssh, with the cloud system running isolated as what is generally called a sandbox.

dman—remotely retrieves man pages from http://manpages.ubuntu.com but reads them on the local system. This is useful to read the man page for a utility you to not have installed on the local system.

pbget—retrieves content uploaded to a pastebin by pbput or pbputs.

pbput—uploads text files, binary files, or entire directory structures to a pastebin. It is similar to pastebinit, covered later, but adds support for binaries and only uses http://pastebin.com.

pbputs—operates exactly like pbput, except the user is prompted for a passphrase for encrypting the content with gpg before uploading. pbget automatically prompts the user for the preshared passphrase when the file is requested.

release—creates a release of a project for Ubuntu.

release-build—takes project information for a bzr project in a Launchpad PPA that uses specific parameters and builds the project as an upstream project that can then be released to Ubuntu.

socks-prox—establishes an encrypted connection for tunneling traffic through a socks proxy.

system-search—performs a unified search through a set of system commands, packages, documentation, and files.

uquick—performs a quick server installation.

what-provides—determines which package provides a specific binary in your path.

wifi-status—monitors a wireless interface for connection and associated information.

The contents of Bikeshed are expected to change over time. Some of these tools may graduate to standalone tools, merge into other existing packages, or get added to more official upstream packages. You can always check the Launchpad page to find a current list of Bikeshed’s contents.

The rest of the tools in this section are not an actual part of Bikeshed but have either graduated from Bikeshed and been spun off as freestanding tools or were developed individually by Dustin or others in the Ubuntu community. All the tools run from the command line and have useful man pages.

Other useful tools that you can find in the Ubuntu repositories include the following:

pastebinit—is a script to upload a file or the result of a command to the pastebin you want and gives you the URL in return. It was written by another Ubuntu developer, Stéphane Graber, and you can find it at https://launchpad.net/pastebinit or from the Ubuntu repositories. By default, it uses http://pastebin.com, but it is configurable to use others such as http://paste.ubuntu.com.

run-one—runs no more than one unique instance of a command with a unique set of arguments. This is often useful with cronjobs, when you want no more than one copy running at a time, but where a cronjob has the potential to run long and finish after the next scheduled run. Also see: run-one-constantly, run-one-until-failure,and run-one-until-success.

run-this-one—is exactly like run-one, except that it uses pgrep and kill to find and kill any running processes owned by the user and matching the target commands and arguments. It blocks while trying to kill matching processes until all matching processes are dead.

keep-one-running—operates exactly like run-one except that it respawns "COMMAND [ARGS]" any time COMMAND exits (zero or nonzero).

ssh-import-id—uses a secure connection to contact a public key server, https://launchpad.net by default, to retrieve one or more user’s public keys and append them to the current user’s ~/.ssh/authorized_keysfile.

bootmail—is called by cron to send an email any time a system is rebooted. It reads a list of one or more comma-separated email addresses from /etc/bootmail/recipients and then loops over a list of whitespace-separated files in /etc/bootmail/logs to construct the email. This is useful to know when remote systems are rebooted.

purge-old-kernels—looks for old kernels on your system and removes them. This is a part of the byobu package.

col1—splits and prints a given column, where the column to print is the name of the script program you are running (col1 to col9). col2 to col9 are symlinks to col1; their behavior simply changes based on the name called. For example, instead of using awk '{print $5}' you can use col5. This used to be in bikeshed but is not part of the byobu package.

wifi-status—monitors a wireless interface for connection and associated information. This used to be in bikeshed but is not part of the byobu package.

References

http://subversion.apache.org/—The main website for Subversion.

http://bazaar.canonical.com/en/—The main website for Bazaar.

http://www.mercurial-scm.org—The main website for Mercurial.

http://git-scm.com/—The main website for Git.

https://launchpad.net/—Launchpad is an open-source website that hosts code, tracks bugs, and helps developers and users collaborate and share.

https://launchpad.net/ubuntu/+ppas—Personal package archives allow source code to be uploaded and built in to .deb packages and made available to others as an apt repository.

http://www.pygtk.org/, based on http://www.gtk.org/—PyGTK is the toolkit most used by Ubuntu developers when creating GUI interfaces with GTK in Python, which is what Quickly is set to do in the ubuntu-application template.

http://glade.gnome.org/—A user interface designer for GTK.

www.freedesktop.org/wiki/Specifications/desktopcouch, http://couchdb.apache.org/ and https://launchpad.net/desktopcouch—Desktop Couch is a data storage format used by Ubuntu One and many desktop programs for easy integration data storage, replication from one computer to another, and synchronization into programs.

http://projects.gnome.org/gedit/—gedit is the default text editor in the GNOME desktop environment.

https://launchpad.net/bikeshed—The main page for Bikeshed.

https://help.ubuntu.com/community/PowerUsersProgramming—Another Ubuntu community page filled with programming resources.