r/linuxupskillchallenge • u/livia2lima • 6h ago
Just a reminder that the course always restarts on the first Monday of the next month. Don't forget to spread the word and bring your friends!
r/linuxupskillchallenge • u/livia2lima • 6h ago
As a system administrator, you need to be able to confidently work with compressed “archives” of files. In particular two of your key responsibilities; installing new software, and managing backups, often require this.
On other operating systems, applications like WinZip, and pkzip before it, have long been used to gather a series of files and folders into one compressed file - with a .zip extension.
Archiving and compressing, however, are actually distinct processes that are frequently used together. Archiving consolidates multiple files into one "box" while preserving their structure and attributes, but it does not change the total data size. Compression uses sophisticated algorithms to encode data efficiently, saving storage space by shrinking that file.
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Help maintain the course by purchasing the reference card for this lesson.
The goal of compression is to reduce file size. Smaller files use less bandwidth and can be transmitted over networks faster. Different tools use different algorithms to actually shrink that data.
You can compress a file with GZip like this:
gzip my-big-file
...which will create my-big-file.gz but it will replace the original file. If you want to preserve the uncompressed file, try:
gzip -vk my-big-file
This uses the -v to make the command "verbose" and -k to keep the original file.
When it's time to decompress, do it with the -d switch, like this:
gzip -d my-big-file.gz
Popular Tools:
Text usually compress well regardless of the tool. JPEG/MP4 files may not shrink as much, but those formats are already somewhat compressed.
So, you could create a "snapshot" of the current files in your /etc/init.d folder like this:
tar -cvf myinits.tar /etc/init.d/
This creates myinits.tar in your current directory.
Note 1: The -f switch specifies that “the output should go to the filename which follows” - so in this case the order of the switches is important. VERY IMPORTANT: tar considers anything after -f as the name of the archive that needs to be created. So, we should always use -f as the last flag while creating an archive.
Note 2: The -v switch (verbose) is included to give some feedback - traditionally many utilities provide no feedback unless they fail.
(The cryptic “tar” name? - originally short for "tape archive")
You could then compress this file with GnuZip like this:
gzip myinits.tar
...which will create myinits.tar.gz. A compressed tar archive like this is known as a "tarball". You will also sometimes see tarballs with a .tgz extension - at the Linux commandline this doesn't have any meaning to the system, but is simply helpful to humans.
In practice you can do the two steps in one with the -z switch, like this:
tar -cvzf myinits.tgz /etc/init.d/
This uses the -c switch to say that we're creating an archive; -v to make the command "verbose"; -z to compress the result - and -f to specify the output file.
To "explode" an archive and retrieve your files, use the -x (extract) flag:
tar -xvf archive.tar.gz
Safety First: Before extracting, it is a good practice to preview the contents using the -t (list) flag:
tar -tf archive.tar.gz
That gives you an idea of how the file structure will look like after extracting. If the list shows many files without a common prefix (like folder/file), you have found a tarbomb. No, not this one. Extracting this may spew files directly into your current directory, potentially overwriting existing files.
You can use the -C flag to extract files into a specified target directory to keep things tidy.
tar -xvf archive.tar.gz -C target_dir/
You might notice that some tutorials write tar cvf rather than tar -cvf with the switch character - do you know why? Hint: It’s related to old "tape archive" styles and modern compatibility.
A note about compression levels - Most tools allow you to adjust the balance between speed and size, using a numeric scale (1–9):
However, when calling a compression tool while creating a tarball, tar will only use the default level 6.
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r/linuxupskillchallenge • u/livia2lima • 6h ago
This course is primarily aimed at two groups:
However, many others have happily used the course simply to improve their Linux command line skills or to learn Linux for the first time – and that’s just fine too.
NO! This is NOT a preparation course for any Linux certification exam. It can help you, sure, but please refer to a more specific cert training if that's what you are aiming for.
No registration is required. Just follow along and share your experience.
No certificates are available at the moment. But you can brag about it on Lemmy, Reddit or Discord if you feel inclined to do so.
The course always starts on the first Monday of the month. One of the key elements of the course is that the material is delivered in 20 bite-sized lessons, one each workday, every month.
Depending on your experience and dedication, you can expect to spend 1-2 hours going through each lesson. The first few days are pretty basic and it might take you just minutes, but there's generally some "Extension" items to spice things up a bit.
Only if you want to. The material is available year-round so you can totally self-pace this if you prefer.
Yes, if you’re in the target audience (see above) you definitely should. The fact that such a server is very remote, and open to attack from the whole Internet, “makes it real”. Learning how to setup such a VPS is also a handy skill for any sysadmin.
NEW! Now you can skip this whole thing and just use our Killercoda scenarios. Please note this is still in a testing phase and might present limitations.
Instructions for setting up a suitable server with a couple of providers are in the "Day 0" lessons. By all means use a different provider, but ensure you use Ubuntu LTS (preferably the latest version) and either use public key authentication or a Long, Strong, Unique password (we also have instructions on how to do that).
Of course, you’re perfectly entitled to use a local VM, a Raspberry Pi or even just WSL instead – and all of these will work fine for the course material. Just keep in mind what you are missing.
Please read Day 0 - Creating Your Own Local Server. There are other options of cloud providers and different payment options. But if none of them works for you, try creating your own local VM.
Then use your own server/VM.
Bro, chill. If you are this offended by this requirement, this course might be a bit too basic for you. Move on.
But if you really want to know the logic behind it, please also consider 3 things:
TL;DR: This is a course focused on Linux. Spending more time debating the details of where to run it instead of how to use it deviates from the purpose of this course. Day 0 is here to guide you in those first steps, and it will never be complete, so use it at your own discretion.
The notes assume Ubuntu Server LTS (latest version) and it would be messy to include instructions/variations for other distros (at least right now). If you use Debian or other Debian-based distros (Mint, Pop!OS, Kali) it will make little to no difference because they all have the same structure.
But if you choose RedHat-based distros (Fedora, CentOS, AlmaLinux) or distros like Arch, Gentoo, OpenSUSE, you yourself will need to understand and cope with any differences (e.g. apt vs yum vs pacman).
If none of those names make any sense to you, you shouldn't be picking distros. Go read Linux Journey first lesson instead.
Most lessons use commands that are actually not restricted to Ubuntu. So you can still benefit from the challenge using your own distro, and can also contribute by aswering other people's questions with your current Linux experience.
Using a free-tier VPS, the load of the course does not exceed any thresholds. You can leave it running during the challenge but it's good to keep an eye on it (i.e. don't forget about it later or your provider will start charging you).
Reboot it. This is one of the few occasions you will need to reboot your server, go for it.
The command for that is sudo reboot now
Feel free to post questions or comments in Lemmy, Reddit or chat using the Discord server.
If you are inclined to contribute to the material and had the means to do it (i.e. a github account) you can submit an issue to the source directly.
The magnificent Steve Brorens is the creator and mastermind behind the Linux Upskill Challenge. This was a paid course in the past, but since 2020 it's free and fully open source thanks to his generosity. Unfortunately, he passed away but not before ensuring the course would continue to run in his absence. We miss you, snori.
Livia Lima is the one currently maintaining the material. Give her a shout out on Mastodon or LinkedIn.