Linux Essentials for Delphi Developers
There is currently no way using Delphi to target Linux. Long ago there was a thing called Kylix that worked on one version of RedHat Linux, barely, back in the 1990s. But in the Community road-map, targeting a fall release, there might be a way to target Linux Servers. Here's hoping. If that happens, or even if that's delayed a bit, now is a fantastic time to hone your Linux skills. I'm not going to tutor you. You can google probably almost as well as I can. But I am going to outline a plan of attack for a competent Windows developer to learn the essentials of Unix systems, with a focus on Linux. I recommend this plan be carried out on a virtual machine inside your main windows PC. You can NOT learn everything there is to know about Linux just by using the Windows Subsystem for Linux. There's no linux kernel, no linux networking stack, no desktop environment in the WSL. Learn on an Ubuntu VM.
My belief is that Linux matters on the Server because:
- It is currently the right way to deploy for the web in 2016.
- It is the right technology for cluster scale technologies.
- It is currently the right way to build systems that are easily administered remotely, whether in the cloud, or at remote sites, or in large numbers.
- It is a lighter weight technology and currently has mature support for containers, big data technologies, and about 1000 other things in that vein.
- It has a better way of upgrading, without requiring as many reboots.
- It has a mature set of binary dependency management (package installer tools), container and orchestration tools.
There are several aspects to learning to be a competent Linux server developer
- You can install, upgrade, troubleshoot and maintain both client and server Linux systems. You know the 50 most common command line tools and their everyday uses. You can log in, change your password, obtain root access, check what groups a userid belongs to, install and remove, and upgrade packages.
- You have installed and learned several different distributions. The entire concept of distributions deserves some study by a person who wants to know what Linux is. You know not only how to use apt-get (on debian and ubuntu) but several alternatives such as those on RedHat/Centos and others. You know roughly what changes from one major family of related distributions to another. I recommend Ubuntu to every beginner, and Debian to every intermediate and advanced user. In some corporate environments, you may find that RedHat Enterprise Linux (RHEL) or its open-source variants CentOS and or Fedora are preferred. I recommend you learn Ubuntu first, and learn a RedHat variant later.
- You know how the Linux boot process works, from BIOS or EFI to the boot loader, to the kernel startup, to the init sequence, and service startups, and you know what runlevels are, and what systemd is, and what /etc/init.d. You appreciate that unlike Windows, when a system refuses to boot, it's not that hard to repair it.
- You are comfortable in the Unix style shells, such as bash, csh, and tcsh. You can write shell scripts and read and repair shell scripts.
- You are familiar with the basics of C development in Linux, including the use of GCC and CLANG, build tools, and associated parts. You can download something.tar.gz and unpack it, read the instructions and build it from source. When it breaks you can read the output and figure out what's wrong, and if googling the error doesn't help, you can dig in and fix it yourself. You know what static and shared libraries are, and you can find and install dependencies (libraries, tools) that some package needs to build.
- You are comfortable with rebuilding the Linux kernel from source code, you know what kernel modules are and what lsmod and modprobe do, and you know how to reconfigure a kernel, turning options on and off. You know how to upgrade or add an additional kernel to your system's boot loader. This is actually really fun. You may find that having a system you can completely and utterly modify to suit your own needs and requirements becomes a bit of a giddy experience. I know that I feel like I'm actually in control of my computer when I run on Linux. On Windows 10, I feel like my machine belongs to Microsoft, and they just let me use it sometimes, when it's not busy doing something for the boys in Redmond. That being said, I really like Windows 10, and I still primarily enjoy developing for Windows systems. But knowing both Linux and Windows is a very useful thing to me.
- You have a decent understanding of system administration core concepts, including the wide set of tools that will be on almost every unix system you use. You can find files using several techniques. You can list processes. You can monitor systems. You know how to troubleshoot networking issues from the command line.
- You will know you've gotten in deep, when you have taken a side on the vi versus emacs debate, and become extremely proficient in the use of one or the other. (Hint: The correct choice here is vi. Die emacs heretics, die die die.)
The above should give you enough to chew on for a year or two. What should your first steps be if you know nothing?
- You will need at least 20 gigs of free space.
- Download the latest Ubuntu 15.xx as an .ISO file.
- Install Ubuntu into a virtual machine. I recommend Client Hyper-V on Windows 10 which is included in Windows 10, or if you're still using that ancient Windows 7 thingy, then download VirtualBox, which is free. If your Linux install worked perfectly, the client integration piece that makes working with a mouse within a virtual operating system will work perfectly. If the client integration piece didn't work, make sure to learn how to manually "free" your mouse pointer from the VM if it becomes locked inside it and you can't figure out how to release it.
- Play with virtual consoles
(Ctrl+Alt+F1 through F8). Learn what they are. Watch some tutorials on
basic Linux stuff like logging in. Learn a bit about bash shell.
Learn about the structure of unix filesystems, learn the basics of unix
file permissions and ownership.
- Learn about commands like ls, find, locate, grep, ps, pswd, more, less, wget, ssh, ping. chmod, chown, and others. Use the man command to learn about them (man grep).
- Learn to install and start up Apache web server. Learn a bit about configuring it. Examine the configuration files in the /etc/apache2 folder
- Browse from your host (Windows) PC web browser to the IP address of your Virtual Machine. Use /sbin/ifconfig eth0 command to display your current IP address from a terminal prompt.
- Learn to start and stop the X Server. When the X server is stopped, you have a text mode only operating system, which is ideal for server deployment. When it's running you have an opportunity to try some of the available IDEs that run on Linux.
- Optional: Learn some Python and learn to write simple web server applications with Python. (I do not recommend bothering to learn PHP, if you don't like Python then look into Ruby and Go as server side languages.)
- Optional: Learn the fundamentals of compiling some small applications from source. Write some small command line applications in C, since that's going to give you a bit of a flavor for the classic Unix environment. C programming on Unix is easily the single most important skill I have on Linux. If you can get over your preference for begin/end and learn to work on Unix in C when it's useful to do so, you become a much more well rounded developer.
- Optional: Install some open source Pascal compiler. Don't expect things to be exactly like Delphi, because they aren't but you might enjoy messing around with FreePascal (compiler), or Lazarus (IDE).
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