Linux servers - Exercice 1
==============

*Disclaimer:*
--------------

This exercise is a part of [Linux servers (ICT4TN021, spring 2018) // Linux-palvelimet (ICT4TN021, kevät 2018)](http://www.haaga-helia.fi/fi/opinto-opas/opintojaksokuvaukset/ICT4TN021) school course organized as a part of Information Technology studies in Haaga-Helia university of Applied Sciences, Helsinki, Finland. Course lecturer [Tero Karvinen](http://terokarvinen.com/) has defined the original assignment descriptions in Finnish presented in this document in English. Answers and translations have been written by Pekka Helenius (me, ~ Fincer).

**a)** Create your own Linux USB live stick. Try it out on a non-school computer. This section does not require installation of Linux. However, if you decided to install Linux, you should take proper backups first.
--------------

**Answer:** I did this with [Rufus Windows application](https://rufus.akeo.ie/) on Microsoft Windows 7 which was run inside [Oracle VirtualBox](https://fi.wikipedia.org/wiki/VirtualBox) as a virtual machine. Alternative methods include [UNetbootin](https://unetbootin.github.io/), [ISO Image Writer](https://github.com/KDE/isoimagewriter) or dd command (default location on Linux: /usr/bin/dd) which is a part of [Coreutils](http://www.gnu.org/software/coreutils/coreutils.html). Rufus allows you to create a live USB stick using either ISO or DD method which differ from each other, as the developer has explained [on his GitHub site](https://github.com/pbatard/rufus/issues/843#issuecomment-255680876).

Let's take a detailed look for two of these approaches: Rufus on Windows 7 and dd command on Linux (any Linux distribution applies here).

**Alternative 1 - Rufus (Windows, GUI-based)**

You can use either Windows 7 or 10 (any student/enterprise/server subversion applies here). You can run Windows either in a virtual machine or as physically installed in your mass media storage (SSD/HDD). Whichever method you choose to run Windows, it doesn't really matter. The most important part is that you have a working operating system.

1. Launch Microsoft Windows
2. Download Rufus application from [here](https://rufus.akeo.ie/), under the title "Download"
3. You can use either portable or installable version of Rufus. In the following example, we use portable version v. 2.18.
4. Download any Linux distribution you prefer. In further parts, Debian-based Ubuntu 16.04.3 LTS is used. What comes to alternative download methods, you can choose either ISO image file (downloaded directly from servers) or distributed torrent method. Torrent method usually requires a client application (such as [Transmission](https://transmissionbt.com/download/)) to work correctly. The Linux distribution of choice can be anything you prefer in your working environment and which requirements you have set up for your Linux server environment.
Let's download a widely used Xubuntu 16.04.3 LTS (x86_64 processor architecture), which is based on Ubuntu 16.04.3 LTS but uses XFCE desktop environment instead of Unity. In Ubuntu version syntax, 16 refers to release year (2016), 04 refers to release month (April), 3 is subversion and LTS stands for Long-Term Support (preferred in server environments).

[Xubuntu 16.04.3 LTS - Torrent download](http://cdimage.ubuntu.com/xubuntu/releases/16.04.3/release/xubuntu-16.04-desktop-amd64.iso.torrent)
[Xubuntu 16.04.3 LTS - ISO image file directly from a server - 1.2G](http://cdimage.ubuntu.com/xubuntu/releases/16.04.3/release/xubuntu-16.04-desktop-amd64.iso)

**Comparing checksums:**

If you wanted to make sure the ISO image you just downloaded is valid, you should check its checksum (mainly for security reasons). In this way you make sure that no malicious party has altered the image you trust and the download process has succeeded. You should take a closer look on sha256sum and md5sum values of your ISO image file. The value must match the one which is published on the Ubuntu download site ([sha256sum](http://cdimage.ubuntu.com/xubuntu/releases/16.04.3/release/SHA256SUMS), [md5sum](http://cdimage.ubuntu.com/xubuntu/releases/16.04.3/release/MD5SUMS)).

On Linux: check checksums with commands *sha256sum xubuntu-16.04-desktop-amd64.iso* and *md5sum xubuntu-16.04-desktop-amd64.iso*

On Windows: Use [Microsoft File Checksum Integrity Verifier](https://www.microsoft.com/en-us/download/details.aspx?id=11533) or check a CertUtil-based solution [given on superuser.com](https://superuser.com/questions/245775/is-there-a-built-in-checksum-utility-on-windows-7/898377#898377)


**NOTE:** Checking checksums is highly recommended. For instance, Linux Mint network servers were hacked due to outdated server software in 2016, resulting to maliciously injected ISO images uploaded by hostile attackers. In addition, the Linux Mint forum software was affected, as well (user credentials leaked). More about the incident is explained [on Linux Mint blog](https://blog.linuxmint.com/?p=2994).

5. Plug in an empty and large enough USB stick into your computer (4GiB should be sufficient). It is highly recommended that you have formatted the stick in advance because Rufus overwrites any existing files existing in the USB stick in order to place required Linux files in the stick. If your stick contained any important files, they should be moved from the stick to somewhere safe location before proceeding here.

6. Once the stick is emptied (and probably formatted), launch Rufus application. Select the USB stick as a target device in *Device* menu. All other settings can be left in their default values. Choose downloaded Xubuntu 16.04.3 LTS ISO image file from the dropdown menu located at the right of *Create a bootable disk using* part. The dropdown menu is presented as a disc icon without any texts.

7. Click *Start*, choose ISO method as a writing method once asked. Read the warnings. If all steps have been successfully accomplished so far, proceed with the writing operation.

8. Wait until the ISO image file has been written into the USB stick. Once done, reboot your computer with the USB stick attached. Immediately the computer has rebooted, press a button which you can access your BIOS/UEFI/Boot options menu with. Choose the Xubuntu 16.04.3 LTS USB stick (which should appear in the boot list). Start the operating system boot-up process bt selecting *Try without installing* option (this step varies between Linux distribution. More generally, you can also choose *Install <whateverdistro>* option and select installation on the live USB Linux desktop environment). Wait until the operating system has been booted up. Start installation and follow the instructions.

The installation process is not defined in detail here because installation steps varies from Linux distribution to distribution. However, basic principle is to install the operating system with good and strong passwords. Encrypted home folder or HDD/SSD partition options should also be considered. After you have successfully installed Linux, detach the live USB stick and reboot your computer. You should be able to access the installed Linux distribution without the USB stick.

When writing and applying passwords, please pay attention to correct keyboard layouts. In my case, I use a Swedish (Finnish) keyboard layout which differs from the default en_US layout. Therefore, mistyping characters can easily happen. Many Linux distributions allow you to change the keyboard layout during the installation process. Unless you're not able to do it in installation window, you can change the keyboard layout temporarily by executing *setxkbmap fi* in a local shell environment (NOTE: graphical environment is required since the command is a part of graphical X11 environment!). You can open up a local shell by opening a terminal emulator while running Linux from your USB stick. NOTE: changing passwords must be done before writing them in the installation steps!

**Alternative 2 - dd command (Linux, CLI-based)**

In case you use any Unix-based operating system (Linux, GNU/Linux, Apple MacOS, FreeBSD), you can create a USB live stick by using shell-based dd command. This method does not require a graphical desktop environment. **NOTE!** Commands on Apple MacOS may not be exactly equal to Linux ones if you use extra parameters in the following commands.

The following instructions assume that you have only a command line environment and you have a working network connection.

1. At first, you need to download an ISO image of your Linux distribution of choice. There are usually two options: download ISO image from a centralized server or download ISO image using torrent protocol. In the following steps, we download Xubuntu 16.04.3 LTS (x86_64).

a. Centralized server:
- requires that *wget command* exists in the system
- download the ISO image with the command:

```
wget --directory-prefix=$HOME --show-progress http://cdimage.ubuntu.com/xubuntu/releases/16.04.3/release/xubuntu-16.04-desktop-amd64.iso
```

b. Torrent download:
- requires that *transmission-cli command* exists in the system
- download the ISO image with the command:

```
transmission-cli -w $HOME http://cdimage.ubuntu.com/xubuntu/releases/16.04.3/release/xubuntu-16.04-desktop-amd64.iso.torrent
```

2. Plug in an empty and large enough USB stick into your computer (4GiB should be sufficient). It is highly recommended that you have formatted the stick in advance but you can format the stick with *fdisk* command, as well ([util-linux](https://www.kernel.org/pub/linux/utils/util-linux/)). When using fdisk, please follow [these instructions](https://www.cyberciti.biz/faq/linux-how-to-delete-a-partition-with-fdisk-command/), for example. In case you have important files to be copied from your USB stick, copy the files with the following command sequence. We assume that the stick is not yet mounted on the system. Command sequence is expected to be executed with the default user (UID = 1000) which belongs to the default user group (GID = 1000). Correct USB stick device name and partition number (*/dev/XdYZ*) must be find out in advance by executing command *sudo fdisk -l*. Y stands for the device's alphabetical ID, Z stands for partition number (*/dev/sda1*, for example). X can have value *h* (IDE-based HDD/SSD's) or *s* (SATA-based HDD/SSD's). Newer NVMe-based storage solutions such as Samsung EVO series 860/960 use syntax */dev/nvme0n1p1* in which 1 stands for the device number and *p1* stands for the partition number.

```
sudo mkdir -p /mnt/livestick && \
mkdir $HOME/livestick-backup && \
sudo mount /dev/sdXY /mnt/livestick && \
sudo mv /mnt/livestick/* $HOME/livestick-backup/ && \
sudo chown -R 1000:1000 $HOME/livestick-backup
```

**NOTE:** If you have any USB stick partitions mounted already on the system, you should **not** use */mnt/livestick** location in above commands. Instead, use the path you can extract for the correct USB stick partition with command *mount*.

3. When you have backed up your important files earlier stored in the USB stick, you have confirmed the USB stick is empty and you have successfully downloaded your Linux distribution ISO image, you can start proceeding with the writing operations.

**NOTE!** You must be extra careful with dd command. If used wrongly, the command can destroy any data you have in your HDD/SSD or in any storage device. Recovering files is a headache and you really don't want to end up having one! One key principle is to triple check all locations given for the dd command and check that used locations are in correct places (so that input and output operations are being executed for correct devices and the devices don't mix up).

4. Let's begin with Xubuntu 16.04.3 LTS USB writing operations. In this section we assume that you have successfully downloaded the ISO image and you definitely know the correct path for your USB stick device (syntax: /dev/sda). **NOTE!** I don't refer to USB stick partition path (syntax: /dev/sda1). The device path syntax is as stated: */dev/sda*, */dev/sdb*, etc. dd command is executed as the root user (Linux main user/super user). dd command doesn't confirm the command syntax is correct so you must write it correctly in the beginning. If you are not sure about the correct syntax, please contant an expert.

The command syntax (NOTE: not likely the exact command in your environment!) is as follows:

```
sudo dd status=progress if=$HOME/xubuntu-16.04-desktop-amd64.iso of=/dev/sdb
```

where /dev/sdb is your USB stick as seen on Linux system. **Use correct, your exact device identifier instead of the one shown above**.

If you want more instructions how to use the 'dd' command, it is recommended to read the following wiki, for example: [Wikipedia - dd (Unix)](https://en.wikipedia.org/wiki/Dd_(Unix))

5. Wait until the ISO image file has been written into the USB stick. Once done, reboot your computer with the USB stick attached. Immediately the computer has rebooted, press a button which you can access your BIOS/UEFI/Boot options menu with. Choose the Xubuntu 16.04.3 LTS USB stick (which should appear in the boot list). Start the operating system boot-up process bt selecting *Try without installing* option (this step varies between Linux distribution. More generally, you can also choose *Install <whateverdistro>* option and select installation on the live USB Linux desktop environment). Wait until the operating system has been booted up. Start installation and follow the instructions.

The installation process is not defined in detail here because installation steps varies from Linux distribution to distribution. However, basic principle is to install the operating system with good and strong passwords. Encrypted home folder or HDD/SSD partition options should also be considered. After you have successfully installed Linux, detach the live USB stick and reboot your computer. You should be able to access the installed Linux distribution without the USB stick.

When writing and applying passwords, please pay attention to correct keyboard layouts. In my case, I use a Swedish (Finnish) keyboard layout which differs from the default en_US layout. Therefore, mistyping characters can easily happen. Many Linux distributions allow you to change the keyboard layout during the installation process. Unless you're not able to do it in installation window, you can change the keyboard layout temporarily by executing *setxkbmap fi* in a local shell environment (NOTE: graphical environment is required since the command is a part of graphical X11 environment!). You can open up a local shell by opening a terminal emulator while running Linux from your USB stick. NOTE: changing passwords must be done before writing them in the installation steps!

**b)** List hardware components of your new Linux computer (*sudo lshw -short -sanitize*).
--------------

**Answer:** *sudo lshw -short -sanitize* gives the following information (assuming that you have package *lshw* installed and proper commands *sudo* and *lshw* are available on the system):

Detailed comments about the listed devices have been included after each terminal output line (therefore, the output is not exactly as written by the command to stdout/output).

H/W path   Device  Class  Description

- system N56JR (ASUS-NotebookSKU)
- /0 busN56JR
**Comment:** *Computer manufacturer & model identifier*
- /0/0   memory 64KiB BIOS 
**Comment:** *Memory size of motherboard's BIOS firmware, 64 kibibytes*
- /0/8   processor  Intel(R) Core(TM) i7-4700HQ CPU @ 2.40GHz 
**Comment:** *Processor manufacturer, model and clock rate*
- /0/8/9 memory 1MiB L2 cache
**Comment:** *Level 2 cache of the processor, size of 1 mebibytes*
- /0/8/a memory 256KiB L1 cache 
**Comment:** *Level 1 cache of the processor, size of 256 kibibytes*
- /0/8/b memory 6MiB L3 cache 
**Comment:** *Level 3 cache of the processor, size of 6 mebibytes*
- /0/c   memory 16GiB System Memory 
**Comment:** *Installed computer RAM memory size in gibibytes*
- /0/c/0 memory 8GiB DIMM DDR3 Synchronous 1600 MHz (0.6 ns) 
**Comment:** *Information of RAM module 0. DIMM (dual in-line memory module), DDR3 (Double Data Rate 3), clock rate 1600 megahertz, latency 0.6 nano seconds*
- /0/c/1 memory DIMM [empty]
**Comment:** *Information of RAM module 1. Empty*
- /0/c/2 memory 8GiB DIMM DDR3 Synchronous 1600 MHz (0.6 ns) 
**Comment:** *Same than RAM module 0 desribed above*
- /0/c/3 memory DIMM [empty] 
**Comment:** *Information of RAM module 3. Empty*
- /0/100 bridge Xeon E3-1200 v3/4th Gen Core Processor DRAM Controller 
**Comment:** *Memory bus controller information. Processor family Xeon E3-1200. So called main controller for any device below in tree*
- /0/100/1   bridge Xeon E3-1200 v3/4th Gen Core Processor PCI Express x16 Controller 
**Comment:** *PCIe x16 bus controller*
- /0/100/1/0 displayGK106M [GeForce GTX 760M] 
**Comment:** *Graphics Card Gerforce GTX 760M, belonging to PCIe x16 bus*
- /0/100/2   display4th Gen Core Processor Integrated Graphics Controller 
**Comment:** *Secondary Graphics adapter (integrated).*
- /0/100/3   multimedia Xeon E3-1200 v3/4th Gen Core Processor HD Audio Controller
**Comment:** *Audio controller belonging to Intel Xeon E3-1200 family*
- /0/100/16  communication  8 Series/C220 Series Chipset Family MEI Controller #1 
**Comment:** *[Intel Management Engine Interface -kontrolleri](https://www.kernel.org/doc/Documentation/misc-devices/mei/mei.txt)*
- /0/100/1a  bus8 Series/C220 Series Chipset Family USB EHCI #2 
**Comment:** *[Enhanced Host Controller Interface](https://en.wikipedia.org/wiki/Host_controller_interface_(USB,_Firewire)) of Intel C220- chipset family number 2 for USB gateways*
- /0/100/1a/1usb1busEHCI Host Controller
**Comment:** *Host controller for the above mentioned device*
- /0/100/1a/1/1  busUSB hub
**Comment:** *[USB extension hub](https://en.wikipedia.org/wiki/USB_hub) splitted to multiple gates*
- /0/100/1a/1/1/1communication  Bluetooth USB Host Controller 
**Comment:** *Bluetooth controller*
- /0/100/1a/1/1/3multimedia ASUS USB2.0 Webcam 
**Comment:** *ASUS USB-based web camera*
- /0/100/1b  multimedia 8 Series/C220 Series Chipset High Definition Audio Controller 
**Comment:** *Audio controller of C220 chipset*
- /0/100/1c  bridge 8 Series/C220 Series Chipset Family PCI Express Root Port #1 
**Comment:** *Port which operates at motherboard's North Bridge, making it possible to use PCIe devices, to track their hierarchy and opening up communication channels between them ([source](https://www.techwalla.com/articles/what-is-a-pci-express-root-port))*
- /0/100/1c.2bridge 8 Series/C220 Series Chipset Family PCI Express Root Port #3 
**Comment:** *Equal to the previous device*
- /0/100/1c.2/0  wlan0   networkAR9485 Wireless Network Adapter 
**Comment:** *WLAN network adapter Atheros AR9485. Interface identifier wlan0 which is seen by the OS commands (can be altered via changing Linux kernel boot parameters in grub/syslinux configuration files)
- /0/100/1c.3bridge 8 Series/C220 Series Chipset Family PCI Express Root Port #4
- /0/100/1c.3/0  eth0networkRTL8111/8168/8411 PCI Express Gigabit Ethernet Controller 
**Comment:** *Ethernet controller RealTek 8111/8168/8411. Interface identifier eth0, which can be checked by using *ifconfig command*, for example
- /0/100/1c.4bridge 8 Series/C220 Series Chipset Family PCI Express Root Port #5
- /0/100/1c.4/0  genericRTS5227 PCI Express Card Reader 
**Comment:** *RealTek RTS5227 PCIe card reader*
- /0/100/1d  bus8 Series/C220 Series Chipset Family USB EHCI #1 
**Comment:** *[Enhanced Host Controller Interface](https://en.wikipedia.org/wiki/Host_controller_interface_(USB,_Firewire)) of Intel C220 chipset family number 1 for USB gateways*
- /0/100/1d/1usb2busEHCI Host Controller 
**Comment:** *Host controller for the above mentioned device*
- /0/100/1d/1/1  busUSB hub 
**Comment:** *[USB extension bus](https://en.wikipedia.org/wiki/USB_hub) splitted to multiple gates*
- /0/100/1d/1/1/2busHighSpeed Hub 
**Comment:** *Centralization of high speed bus*
- /0/100/1d/1/1/2/3  input  USB-PS/2 Optical Mouse 
**Comment:** *Optical HID mouse device attached to USB bus*
- /0/100/1d/1/1/2/4  input  Logitech Illuminated Keyboard 
**Comment:** *HID keyboard device attached to USB bus*
- /0/100/1f  bridge HM86 Express LPC Controller 
**Comment:** *[Low Pin Count controller](https://en.wikipedia.org/wiki/Low_Pin_Count) which attaches all low-level legacy devices to the motherboard*
- /0/100/1f.2storage8 Series/C220 Series Chipset Family 6-port SATA Controller 1 [AHCI mode] 
**Comment:** *SATA controller of C220 chipset family for SATA-based mass media storage inputs*
- /0/100/1f.3bus8 Series/C220 Series Chipset Family SMBus Controller 
**Comment:** *Power management [System Management Bus controller](https://en.wikipedia.org/wiki/System_Management_Bus)*

P.S. If you frequently listed your hardware on a Linux computer, you should consider creating a *bash alias command* for this purpose (assuming your default shell environment is bash). Basic idea is to simplify commands you need to type each time you want to do something. For listing hardware, write a the following in your _$HOME/.bashrc_ file (it's a hidden file):
```
alias listhw='sudo lshw -short -sanitize'
```

Next time you launch a bash shell session, you should be able to list your hardware by simply executing command *listhw*, defined in your _$HOME/.bashrc_ file.

If you want to create this command globally accessible for all users, you can write the above code in /etc/bash.bashrc file as root. Alternatively, create a file _/usr/bin/local/listhw_ as root with the following contents:
```
#!/bin/bash

sudo lshw -short -sanitize
```

Use command _sudo nano _/usr/bin/local/listhw_ for that.
The file is not executable by default. In order to make it executable, apply the following command:

```
sudo chmod +x /usr/bin/local/listhw
```

Alternative and additional commands to list hardware are *lspci* (list PCI devices), *hwinfo* (defailed output), *lsusb* (list USB devices). Availability of these commands vary and you may need to install extra packages in your Linux distribution. On Ubuntu, execute the following command:

```
sudo apt-get update && sudo apt-get install hwinfo pciutils usbutils
```

**c)** Install three new programs which are new to you. Try them out in their main target environment and primary use.
--------------

**Answer:**

Let's install three new programs: *[Thunar](http://thunar.xfce.org/)* (file manager), *[Gedit](https://wiki.gnome.org/Apps/Gedit)* (text editor), *[GParted](http://gparted.sourceforge.net/)* (mass storage partition editor, alternative [GitHub link](https://github.com/GNOME/gparted)
)
**Thunar:**

![Thunar](https://winaero.com/blog/wp-content/uploads/2017/09/Thunar-in-XFCE4.png)

Thunar is a user-friendly and easily understandable [GTK+-based](https://en.wikipedia.org/wiki/GTK+) file manager. It's not as customizable as [Qt-based](https://en.wikipedia.org/wiki/Qt_%28software%29) [Dolphin](https://www.kde.org/applications/system/dolphin/) but sufficient for daily basic usage. Thunar is the default file manager for [XFCE desktop environment](https://en.wikipedia.org/wiki/Xfce).

**Gedit:**

![Gedit](http://mattbaker.eu/imgs/2017-08/10686759591_gedit-editor-for-windows.jpg)

Gedit is a simple GTK+-based text editor, targeted to [GNOME desktop environment](https://en.wikipedia.org/wiki/GNOME). Alternative text editors are, for example, [Mousepad](https://github.com/codebrainz/mousepad), [Kate](https://www.kde.org/applications/utilities/kate/), [KWrite](https://www.kde.org/applications/utilities/kwrite/) and [Geany](https://en.wikipedia.org/wiki/Geany).

**GParted:**

![GParted](http://intodarkness.eu/imgs/2017-08/23065514301_gparted-live-0-9-1-1-iso.jpg)

GParted is a popular GTK+-based graphical front-end for CLI-based, GPL3-licensed [GNU Parted](http://www.gnu.org/software/parted/parted.html) back-end. Similar programs include a Qt-based [KDE Partition Manager](https://www.kde.org/applications/system/kdepartitionmanager/), targeted mainly to [KDE](https://en.wikipedia.org/wiki/Kde) and [LXQt](https://en.wikipedia.org/wiki/LXQt) desktop environments.

**Installation of Thunar, Gedit and GParted on Debian-based distributions**

**Via official package repositories:**
On Debian-based distributions (like Xubuntu), you can install the selected three programs with a single command, like:

```
sudo apt-get update && sudo apt-get install -y thunar gedit gparted
```

where _sudo apt-get update_ stands for "Update and synchronize package database list to correspond with newer available program versions", _&&_ stands for "If the previous command was successful, proceed with the following command", _sudo apt-get install -y_ stands for "Install the following packages without confirming (-y parameter)", and finally, _thunar gedit gparted_ stands for "Application names found in the available repositories listed in _/etc/apt/sources.list_ file and in files in _/etc/apt/sources.list.d/_ directory and which are parameters for _apt-get_ command".

_sudo_ part before the forementioned commands stands for "Grant me temporary root privileges to execute the following commands as root". It is essential that the current user is in _sudo_ group and all members of group _sudo_ are allowed to gain temporary root privileges (uncomment line _%sudo  ALL=(ALL) ALL_ in file _/etc/sudoers_ as root).

By executing the above command, we assume that the system has established internet connection, [Dpkg](https://en.wikipedia.org/wiki/Dpkg) works as intended (it has not already locked file */var/lib/dpkg/lock*, for example) and no other installation process is being executed on.

You can execute the command without sudo in root terminal, but accessing root terminal is not highly recommended in server environments. In root terminal, the command would be:

```
apt-get update && apt-get install -y thunar gedit gparted
```

You can search for any packages with *apt-cache search package-name* command. It may not be the primary approach but you can search for packages on official [Ubuntu repositories website](https://packages.ubuntu.com/) on Linux Ubuntu distributions (Xubuntu, Ubuntu, Lubuntu, Kubuntu, Ubuntu Bugdie and so on). Alternatively, you can also install packages with *aptitude* command if you have installed package *aptitude*. Command syntax for installing packages with aptitude is

```
sudo aptitude install package-name
```

**Via local packages or from source code:**

If you consider installing local packages, keep in mind that you need to track all required package dependencies. This can easily lead to [Dependency hell](https://en.wikipedia.org/wiki/Dependency_hell) situation. Therefore, installing local packages suits best for commercial, separately distributed software which are bundled with their dependencies and can be installed out-of-the-box without worrying about dependencies.

All installable packages on Debian-based Linux distributions are known as _deb packages_ with suffix _.deb_. Therefore, local packages can be installed with the following command:

```
sudo dpkg -i my-deb-package.deb
```

If any unsatisfied dependencies are present, you should do as usually instructed:

```
sudo apt-get -f install
```

Please note that this does not always work, can break your system and make things just too troublesome to sort out. For example, your program may depends on a previous version of a package which is already installed or your system or/and not available on the official repositories. Installing a previous version can seriously break your system. In some rare cases, packages can be offered with two versions where the older version is known as _compatibility package_, usually installing older library versions to your system, co-existing with newer ones. However, keep in mind that your _.deb_ package must be aware of this _compatibility version_ (so that it depends exactly on that compatibility version instead of the officially named one. This is just a naming issue).

You can force package installation on the system, ignoring package dependencies. In this case, you **must** know what you're doing, and this approach is really not recommended for Linux novices.

If you want to compile software directly from source, you essentially need *[dh_make](https://manpages.debian.org/jessie/dh-make/dh_make.8.en.html)* and *[dpkg-buildpackage](http://man7.org/linux/man-pages/man1/dpkg-buildpackage.1.html)* commands available on your Debian-based operating system. Usually *[cmake](https://cmake.org/)*, *[make](https://en.wikipedia.org/wiki/Make_(software))* and *gcc* ([GNU Compiler Collection](https://gcc.gnu.org/)) are required as well. Not forgetting any extra _build time dependencies_, usually marked with _-dev_ suffix (development headers) in Debian-based Linux distributions. _Runtime dependencies_ can be described in package description.

Any package dependencies (buildtime or runtime) are defined in Debian control file which can be supplied with the package or you need to create and configure it by your own.

On Ubuntu, you can install most essential and widely used build time tools with:

```
sudo apt-get install build-essential
```

if you considered installing a remotely available package directly from source, you should find out required runtime and buildtime dependencies with (assuming you have aptitude installed):

```
aptitude show package-name
```

where package-name is the package of your choice. Replace this string with the correct name,

Additionally, you can investigate required dependencies by checking any header (_.h_) files required in C/C++ source files, if the program is based on these languages. By tracking down required headers it is possible to figure out required dependencies in some extent. In addition, check out official websites of the program (GitHub, BitBucket or another homepage), possibly contant the developer and/or check out any supplied library files (suffix is _.so_) and their dependencies with [ldd command](https://en.wikipedia.org/wiki/Ldd_%28Unix%29). On Ubuntu, you can also check out [packages.ubuntu.com](https://packages.ubuntu.com/) for dependencies if the package is available on official repositories.

Please see my practical [example 1](https://github.com/Fincer/linux_server_setup/blob/master/scripts/compile-xcmenu-screenshot.sh) and [example 2](https://github.com/Fincer/winecfg_patch) for compiling software on Linux.

You can also apply patches directly to source code of a program by using [diff](https://www.gnu.org/software/diffutils/manual/html_node/Example-Unified.html) and [patch](https://en.wikipedia.org/wiki/Patch_%28Unix%29) commands. Patches must be applied before compiling the program.

**Removal of packages:**

You can effectively remove packages on Debian-based Linux distributions with:

```
sudo apt-get purge --remove package1 package2 package3
```

In some cases, package manager suggests you to remove any orphaned packages with:

```
sudo apt-get autoclean
```

You can freely explore more _apt-get commands_ with:

```
apt-get --help
```

and by reading command-related manual page:

```
man apt-get
```

Manual pages in any commands are highly supported in multiple Linux distributions. The command syntax is always the same: _man my_command_. Additionally, _--help_ paremeter is widely accepted by many Unix/Linux CLI programs.

**NOTE:** Although Linux distributions don't have any similar to Windows registry hell (unclean registry after software removal), keep in mind that any  configuration files created _afterwards_ by a Linux program are not handled by Linux package managers. In other words: package managers can't track files created afterwards by your program. This is mostly a case with personal configuration files in user's home directory on Linux. In addition, any backup files (suffix: .old, ~, .bak, .pacnew...) are not included in the package according to your package manager and, therefore, they may not be uninstalled by simply removing a program. [Please see my script for tracking down those files](https://github.com/Fincer/linux_server_setup/blob/master/scripts/file-and-dirs-owner.sh)

**Other Linux distributions:**
Main differences between various Linux distributions are:

- version modeling: For example, Arch Linux follows [rolling release model](https://en.wikipedia.org/wiki/Rolling_release) whereas Ubuntu follows [time based release model](https://wiki.ubuntu.com/TimeBasedReleases)

- package managers: OpenSUSE uses [zypper](https://en.opensuse.org/Portal:Zypper), Fedora uses [dnf](https://lists.opensuse.org/opensuse-factory/2017-08/msg00369.html), Arch Linux uses [pacman](https://wiki.archlinux.org/index.php/pacman)

- package configurations (configuration files, features available for a program by default)

- compilation methods for source codes: For example, Arch Linux uses [makepkg](https://wiki.archlinux.org/index.php/makepkg), Ubuntu uses dpkg-buildpackage

- package availability in official repositories: For example, some packages available on Arch Linux are not available on Ubuntu

- package versioning syntax: For example, Arch Linux uses version 59.0.1-1 and Ubuntu uses 59.0.1 for a same package

- package versions: For example, Arch Linux has newer package version in the official repositories than Ubuntu does.

You can read more at [Arch Linux Wiki - Arch compared to other distributions](https://wiki.archlinux.org/index.php/arch_compared_to_other_distributions).

**d)** What licenses have been used in the programs of your choice? Explain briefly which kind of rights and duties these licenses have. 
--------------

**Answer:**

License information can be retrieved from multiple various sources. Licensing terms have usually been mentioned in source code or documentation, help manual, program website or retriavable from equivalently trusted source.

- Thunar is a part of Xfce project and licensed under GPL ([GNU General Public License](https://www.gnu.org/licenses/licenses.html#GPL)) and LGPL2.1 ([Lesser GNU General Public License](https://www.gnu.org/licenses/licenses.html#LGPL)). Detailed information about the licensing policy can be found on [Arch Linux package repository](https://www.archlinux.org/packages/extra/x86_64/thunar/), for example.

- Gedit is a part of GNOME project and licensed under GPLv2. Licensing terms are mentioned in [Gedit source code](https://git.gnome.org/browse/gedit/tree/COPYING).

- Gparted is a part of GNOME project and uses GPLv2+ license, according to [the official website](http://gparted.sourceforge.net/), bottom section. Exact statement is as follows: "GParted is distributed under the GNU General Public License version 2 or (at your option) any later version."

GPL license is targeted to distribute free sofware under several terms. The license grants permission to use, copy, modify and share a program and its source code. License is accumulating in nature so that any program initially released under GPL and developed further source code must be published and any further restrictions to usage of the program are forbidden. License allows commercial usage of a program. More about the license on [GNU project homepage](https://www.gnu.org/licenses/quick-guide-gplv3.html)

[LGPL license](https://en.wikipedia.org/wiki/GNU_Lesser_General_Public_License) differs from GPL license so that some non-GPL licensed component of a program can be linked to otherwise GPL-licensed program. Therefore, because the program is not fully open source, it can still use LGPL license but not GPL license. LGPL licensed program has less efficient [copyleft](https://en.wikipedia.org/wiki/Copyleft).

**e)** List programs you use (MS Word, for example), purpose of these programs (for example, text editing) and introduce equivalent open source Linux program (for example, LibreOffice Writer). List closed source programs even if they do not have open source equivalent for Linux.
--------------

**Answer:**

Syntax: Closed source program, open source program, purpose of the selected program

- Adobe Photoshop - *Open source:* Krita, GIMP = **Image manipulation**
- Adobe Lightroom - *Open source:* Darktable, RawTheRapee, digikam = **Photo editing**
- Microsoft Media Player - *Open source:* VLC, mplayer = **Media player**
- Notepad - *Open source:* Kate, Leafpad, gedit = **Text editor**
- Windows File Manager - *Open source:* Nautilus, Thunar, Dolphin = **File manager**
- Autodesk 3DS Max - *Open source:* Blender = **3D editor**
- Microsoft Paint - *Open source:* KolourPaint = **Rasterized image editing**
- Skype - *Open source:* Pidgin Internet Messenger = **Chat**
- Microsoft Windows - *Open source:* Wine = **Operating system (note! this can be debated. ReactOS, too)**
- Windows Task Manager - *Open source:* KSysGuard, LXTask = **Process and system statistics manager**
- Microsoft Outlook - *Open source:* Thunderbird, Kmail = **Email client**
- Windows Volume Control - *Open source:* PulseAudio Volume Control & alsamixer = **Audio controlling**
- Windows Control Panel - *Open source:* KDE System Settings (systemsettings5) = **General settings of an operating system**
- Adobe Acrobat - *Open source:* Evince = **PDF document viewer**
- Windows Image Viewer - *Open source:* Gwenview = **Photo previewing**
- Microsoft Internet Explorer - *Open source:* Firefox, Palemoon, Konqueror = **Internet browser**
- Microsoft Office, WPS Office - *Open source:* LibreOffice, OpenOffice, Calligra = **Set of programs to process office documents**
- Riegl RiScan Pro - *Open source:* CloudCompare, MeshLab = **LiDAR processing software**
- MathWorks MATLAB - *Open source:* FreeMat, GNU Octave = **Mathematical & physical calculations**
- Adobe Audition - *Open source:* Audacity = **Audio editor**
- Tux Racer = **Driving game (open source, mentioned just for fun...)**
- Bentley MicroStation = **City/Urban planning oriented CAD program (closed source, only for Windows)**
- Valve Steam = **Game publishing platform (closed source, available for Linux, too)**
- Pitney Bowes MapInfo Professional = **Map and GIS planning (closed source, only for Windows)**
- IrfanView = **Image previewer (closed source, only for Windows)**
- etc...

**f)** Optional extra task: backup your files (you can use an external USB storage, for example)
--------------

**Answer:** Depending on the final goal/purpose, alternative methods can be used. Creating a backup of whole HDD/SSD's is possible with a single dd command (recommended parameter 'status=progress' with large partitions) and with a USB live stick so that this partition/HDD/SSD is not mounted. More sophisticated tools include [Clonezilla](https://en.wikipedia.org/wiki/Clonezilla), for example. It is recommended to backup a server with slightly different methods.

If the purpose is to copy single files from a location to another location, use *cp* or *rsync* command.

```
cp -Rp /mnt/my_hdd1/somefilefolder/* /mnt/my_hdd2/backupfolder/
```

where -R stands for "recursive copy" and "-p" stands for "preserve file & folder permissions". Asterix symbol (*) stands for "include all files".

Rsync:

```
rsync -axHAWXS --numeric-ids --info=progress2 /mnt/my_hdd1/somefilefolder/ /mnt/my_hdd2/backupfolder/
```

**NOTE:** If you copy files between ext2/3/4 and NTFS file systems, keep in mind that any permissions stored in ext2/3/4 partition are not preserved in NTFS partition. NTFS is widely used on Microsoft Windows environments whereas ext2/3/4 are widely used on Unix-based (POSIX) environments.

In addition, you must consider any [symbolic links](https://en.wikipedia.org/wiki/Symbolic_link) included in copy process. Keep in mind to watch out user permissions as well (does the current user have permissions to copy selected files?).
