In the last two weeks, Peter Zaitsev published a 4-part series on measuring Linux performance on this blog.

His writings cover the 4 main areas where you can spot performance problems on any Linux machine, with practical tips on how to draw the right conclusions. Here are the individual pieces:

Measuring Linux Performance: CPU
Measuring Linux Performance: Disk
Measuring Linux Performance: Memory
Measuring Linux Performance: Network

I found these gave a good overall summary of the things to be on the look-out for whenever you’re troubleshooting slow applications or slow servers.

Ever tried comparing MySQL's my.cnf from a Debian and a Gentoo machine with diff(1) without going crazy?

diff(1) is an awesome tool, you use it (or similar implementations like git diff, svn diff etc) every day when dealing with code. But configuration files aren't code. Indentation often does not matter (yeah, there is diff -w and yeah, people use YAML for configs), order of settings does not matter and comments are just beautiful noise.
How?

cfgdiff will try to parse your configuration files, fetching all the relevant keys and values from them and then pretty-printing them in the original format. These results are then diffed and the diff is shown to you.

• With --indicator (or -q or 'set indicator') nano will show a kind
of scrollbar on the righthand side of the screen to indicate where
in the buffer the viewport is located and how much it covers.
• With <Alt+Insert> any line can be "tagged" with an anchor, and
<Alt+PageUp> and <Alt+PageDown> will jump to the nearest anchor.
When using line numbers, an anchor is shown as "+" in the margin.
• The Execute Command prompt is now directly accessible from the
main menu (with ^T, replacing the Spell Checker). The Linter,
Formatter, Spell Checker, Full Justification, Suspension, and
Cut-Till-End functions are available in this menu too.
• On terminals that support at least 256 colors, nine new color
names are available: pink, purple, mauve, lagoon, mint, lime,
peach, orange, and latte. These do not have lighter versions.
• For the color names red, green, blue, yellow, cyan, magenta,
white, and black, the prefix 'light' gives a brighter color.
Prefix 'bright' is deprecated, as it means both bold AND light.
• All color names can be preceded with "bold," and/or "italic,"
(in that order) to get a bold and/or italic typeface.
• With --bookstyle (or -O or 'set bookstyle') nano considers any
line that begins with whitespace as the start of a paragraph.
• Refreshing the screen with ^L now works in every menu.
• In the main menu, ^L also centers the line with the cursor.
• Toggling the help lines with M-X now works in all menus except
in the help viewer and the linter.
• At a filename prompt, the first <Tab> lists the possibilities,
and these are listed near the bottom instead of near the top.
• Bindable function 'curpos' has been renamed to 'location'.
• Long option --tempfile has been renamed to --saveonexit.
• Short option -S is now a synonym of --softwrap.
• The New Buffer toggle (M-F) has become non-persistent. Options
--multibuffer and 'set multibuffer' still make it default to on.
• Backup files will retain their group ownership (when possible).
• Data is synced to disk before "... lines written" is shown.
• The raw escape sequences for F13 to F16 are no longer recognized.
• Distro-specific syntaxes, and syntaxes of less common languages,
have been moved down to subdirectory syntax/extra/. The affected
distros and others may wish to move wanted syntaxes one level up.
• Syntaxes for Markdown, Haskell, and Ada were added.

Rewritten in Rust: Modern Alternatives of Command-Line Tools
https://zaiste.net/posts/shell-commands-rust/

After a prolonged period of inactivity, new devs have taken over to support
htop. The new 3.0 release features lots of improvements (
https://github.com/htop-dev/htop/blob/master/ChangeLog ), mostly to
underlying low-level items.

eDEX-UI is an open-source cross-platform terminal emulator that presents you with a Sci-Fi inspired look along with useful some features as well.

It was originally inspired from the DEX UI project. It is also worth noting that eDEX-UI is no longer maintained but it hasn’t been completely abandoned. You can learn more about the current status of the project here.

Even though eDEX-UI is more about the looks and the futuristic theme for a terminal, it could double up as a system monitoring tool for Linux in the future if the development resumes or if someone else forks it. How? Because it shows system stats in the sidebar while you work in the terminal.

User-friendly, colorful output
Adjusts to your terminal's width
Sort the results according to your needs
Groups & filters devices
Can conveniently output JSON

In this course, students will learn to develop complex system-level software in the C programming language while gaining an intimate understanding of the Unix operating system (and all OS that belong to this family, such as Linux, the BSDs, and even Mac OS X) and its programming environment.

Topics covered will include the user/kernel interface, fundamental concepts of Unix, user authentication, basic and advanced I/O, fileystems, signals, process relationships, and interprocess communication. Fundamental concepts of software development and maintenance on Unix systems (development and debugging tools such as "make" and "gdb") will also be covered.

Students are expected to have a good working knowledge of the C programming language, have written non-trivial programs before, and to be able to competently use a Unix system with a command-line shell interface. All coursework will be done exclusively on a Unix system from the command-line. This is not an introduction to using Unix!

https://stevens.netmeister.org/631/

So you've heard of this thing called cgroups, and you are interested in finding out more. Perhaps you caught mention of it while listening to a talk about containerization. Maybe you were looking into Linux performance tuning, or perhaps you just happened to be traversing your file system one day and discovered /sys/fs/cgroups. Either way, you want to learn more about this functionality that has been baked into the kernel for quite some time. So sit back, grab some popcorn, and prepare to (hopefully) learn something you may not have known before.

Using the Awk programming language, you can manipulate or extract data, generate reports, match patterns, perform calculations, and more, with great flexibility. Awk allows you to accomplish somewhat difficult tasks with a single line of code. To achieve the same results using traditional programming languages such as C or Python would require additional effort and many lines of code.

You still generate a public-private key pair for each developer. However, you don’t upload the public keys to your servers.

Instead, you sign the public keys with a so-called certificate authority (CA) key which you generate before. This signing simply generates a third certificate file which you give back to the developer and they put it inside of their .ssh/ folder next to the private and public key.

On the servers, you simply tell the server the public key of your CA and the server can detect if a user has a properly signed certificate and only allows access to the developers who have such a signed certificate.

Today in some versions of Linux ls puts single quotes around file names which contain white space likely in order to have those paths easier to copy and paste, but it does so only if !isatty().

I’m not a great fan of changing a program’s well-known behaviour, specially in a case such as with GNU ls which already uses an environment variable for coloring output; it would likely have been easy to augment that for the file name quoting.

It used to be simpler to teach. (But I don’t really teach Unix beginners any more.) :-)

A load testing tool capable of performing real-time analysis, inspired by vegeta and jplot.

Changes in behavior

The message that a binary file matches is now sent to standard error
and the message has been reworded from "Binary file FOO matches" to
"grep: FOO: binary file matches", to avoid confusion with ordinary
output or when file names contain spaces and the like, and to be
more consistent with other diagnostics. For example, commands
like 'grep PATTERN FILE | wc' no longer add 1 to the count of
matching text lines due to the presence of the message. Like other
stderr messages, the message is now omitted if the --no-messages
(-s) option is given.

Two other stderr messages now use the typical form too. They are
now "grep: FOO: warning: recursive directory loop" and "grep: FOO:
input file is also the output".

The --files-without-match (-L) option has reverted to its behavior
in grep 3.1 and earlier. That is, grep -L again succeeds when a
line is selected, not when a file is listed. The behavior in grep
3.2 through 3.4 was causing compatibility problems.

This is VT-100 and XTerm compatible video terminal implemented on the PIC32 microcontroller. It has a serial interface with TTL or RS-232 signal levels, input from a standard PS/2 keyboard, and output to a VGA monitor. There is also a USB interface that supports serial over USB and acts as a USB-to-serial converter.

Over the years I’ve collected a rather messy ~/.ssh/config which resulted in some undesired behavior as a result of me misunderstanding how the config file prioritizes its options.

Today I investigated that.
In short, this is what I found:

Priority goes from top to bottom
Defaults MUST come last
Host specificity is NOT a factor of priority
Host sections can be specified multiple times
Multiple hostnames (and aliases) may be specified per section
Host sections apply to the name you use (not what it resolves to)

Did you know that #Unix groups have passwords? Apparently if you set one, you then have to use newgrp to log in to that group.

I have never seen anyone use unix group passwords.

There are some things to say about this, but the first thing you might wonder is why the newgrp command exists at all. The best answer is that it's mostly a Unix historical relic (or, to put it another way, a fossil).

JuliaMono is a monospaced typeface designed for programming in the Julia Programming Language and in other text editing environments that require a wide range of specialist and technical Unicode characters.

Cursus writes your commands into an sqlite db. With cursus you can search for commands and the searched term will be highlighted if it was found.

Xonsh is Python with added shell syntax thrown in. This makes it an ideal, intuitve way to interact with your computer. You probably already know Python, and so xonsh allows you to run command line applications with out needing to learn a new, arcane syntax when ever you want to use a for-statement.