The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

  • My badges

  • Twitter Updates

  • My Flickr Stream

  • Pages

  • All categories

  • Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 4,227 other subscribers

Archive for the ‘*nix’ Category

The CPU load average metric often is not a good one to alert on

Posted by jpluimers on 2023/04/20

Boy I wish threads with more than one person could be saved by the ThreadReaderApp.


[WayBack] Thread by @mipsytipsy: oh boy.. i was just idly musing over how the single most ubiquitous/useless metric is “CPU load average”, lol i wonder if you could use CPU…

oh boy.. i was just idly musing over how the single most ubiquitous/useless metric is “CPU load average”, lol

i wonder if you could use CPU load alerts to score how modern and powerful a team’s toolchain is, like a Waffle House Index for tooling. 🤔


…oh oh! but i was gonna say, this thread between @drk and @shelbyspees is a killer nanotutorial in how to ask better questions about your code — where to start, how to drill down and dig in, how to instrument, and how to approach such an open-ended exploratory jaunt. 👏🐝❤️

it’s a really good illustration of this thing we end up saying all the time, which is “don’t fear the future, it is simpler and clearer and *easier* here! the way you are doing it NOW is the hard way!” 😖

time for cpu load average to go the way of the PC LOAD LETTER …

/ 0:01



Read the rest of this entry »

Posted in *nix, Cloud, Development, DevOps, Infrastructure, Power User, Software Development, Systems Architecture | Leave a Comment »

xxd examples of big/little/middle endianness (thanks @jilles_com!)

Posted by jpluimers on 2023/04/18

Cool one-liner program via [Archive] Jilles🏳️‍🌈 (@jilles_com) / Twitter:

for s in 0123456789ABCDEF Passwd:admin;do echo -en "Big    Endian: $s\nMiddle Endian: ";echo -n $s|xxd -e -g 4 | xxd -r;echo -en "\nLittle Endian: ";echo -n $s|xxd -e -g 2 | xxd -r;echo -en "\nReversed     : ";echo -n $s|xxd -p -c1 | tac | xxd -p -r;echo -e "\n";done

Note that the hex are bytes, not nibbles, so the endianness is OK:


Big Endian: 0123456789ABCDEF
Middle Endian: 32107654BA98FEDC
Little Endian: 1032547698BADCFE
Reversed : FEDCBA9876543210

Big Endian:
Middle Endian: .2710.61452.
Little Endian: 71.2610.2.45
Reversed : 452.0.61.271

Big Endian: Passwd:admin
Middle Endian: ssaPa:dwnimd
Little Endian: aPssdwa:mdni
Reversed : nimda:dwssaP

That nibble/byte thing confused me at first (as I associate hexadecimal output with hex dumps, where each hexadecimal character represents a nibble)) so here are some interesting messages from the thread that Jilles_com started:

Some related man pages:


Posted in *nix, *nix-tools, bash, Development, Power User, Scripting, Software Development, xxd | Leave a Comment »

Installing Windows OpenSSH from the command-line on Windows 10 and 11

Posted by jpluimers on 2023/03/28

While writing On my reading list: Windows Console and PTY, I found out that OpenSSH had become available as an optional Windows feature.

It was in [Wayback/] Windows Command-Line: Introducing the Windows Pseudo Console (ConPTY) | Windows Command Line:

Thankfully, OpenSSH was recently ported to Windows and added as a Windows 10 optional feature. PowerShell Core has also adopted ssh as one of its supported PowerShell Core Remoting protocols.

Here are a few links:

Read the rest of this entry »

Posted in *nix, *nix-tools, Communications Development, ConPTY, Console (command prompt window), Development, Internet protocol suite, OpenSSH, Power User, SSH, ssh/sshd, TCP, Windows, Windows 10, Windows 11 | Leave a Comment »

llamasoft/polyshell: A Bash/Batch/PowerShell polyglot!

Posted by jpluimers on 2023/03/16

PolyShell is a script that’s simultaneously valid in Bash, Windows Batch, and PowerShell (i.e. a polyglot).

[Wayback/Archive] llamasoft/polyshell: A Bash/Batch/PowerShell polyglot!

Need to check this out, as often I have scripts that have to go from one language to the other or vice versa.

Maybe it enables one language to bootstrap functionality in the other?

The quest

The above polyglot started with a quest to see if I can could include some PowerShell statements in a batch file with two goals:

  1. if the batch file started from the PowerShell command prompt, then execute the PowerShell code
  2. if the batch file started from the cmd.exe command prompt, then have it start PowerShell with the same command-line arguments

The reasoning is simple:

  1. PowerShell scripts will start from the PATH only when PowerShell is already running
  2. Batch files start from the path when either cmd.exe or PowerShell are running

Lots of users still live in the cmd.exe world, but PowerShell scripts are way more powerful, and since PowerShell is integrated in Windows since version 7, so having a batch file bootstrap PowerShell still makes sense.

Since my guess was about quoting parameters the right way, my initial search for the link below was [Wayback/Archive] powershell execute statement from batch file quoting – Google Search.

I have dug not yet into this, so there are still…

Many links to read

These should give me a good idea how to implement a polyglot batch file/PowerShell script.


Posted in *nix, *nix-tools, bash, bash, Batch-Files, Development, JavaScript/ECMAScript, Perl, Polyglot, Power User, PowerShell, Scripting, Software Development | Leave a Comment »

linux – Newline-separated xargs – Server Fault

Posted by jpluimers on 2023/03/07

A long time ago, on just one system, I forgot which one, I needed explicit [Wayback/Archive] linux – Newline-separated xargs – Server Fault.

The simple solution was to replace the newline with null before running xargs:

tr '\n' '\0'

The clean solution was to install gnu xargs:

GNU xargs (default on Linux; install findutils from MacPorts on OS X to get it) supports -d which lets you specify a custom delimiter for input, so you can do

ls *foo | xargs -d '\n' -P4 foo 


Posted in *nix, *nix-tools, bash, Development, Power User, Scripting, Software Development, xargs | Leave a Comment »

%d bloggers like this: