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

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Archive for the ‘*nix-tools’ Category

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Good read for starting to intermediate ssh users is “SSH Essentials: Working with SSH Servers, Clients, and Keys | DigitalOcean” and pointers to more advanced reading material

Posted by jpluimers on 2020/06/08

For a really nice overview of most basic and intermediate usage of ssh, read [WayBack] SSH Essentials: Working with SSH Servers, Clients, and Keys | DigitalOcean.

It is large (printed to PDF it is 30+ pages in either A4 or Letter format) but well worth reading as it covers a lot in manageable bits.

Does it mean I won’t write about ssh again?

I will continue, as most of my blog posts are relatively short highlighting a small thing at a time (that is how I learn best, hopefully some of you do as well).

It does not explain really advanced stuff (like ProxyCommand), so here is a start of things I want to learn more about:

–jeroen

Posted in *nix, *nix-tools, Power User, ssh/sshd | Leave a Comment »

Cursor Movement in bash: either echo escape sequences or use tput

Posted by jpluimers on 2020/06/03

I read [WayBack] Cursor Movement earlier than [WayBack] Colours and Cursor Movement With tput and [WayBack] The Floating Clock Prompt.

So in one of my scripts I’ve now used an escape sequence, but I might change it to tput in a future version:

## Move one line up, then write finished scripts:
echo -e "\033[1A$finished\r"

I would probably have started with put if I had read [WayBack] bash – Set or change vertical position of the cursor – Stack Overflow first.

–jeroen

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

How do I delete a Bash function? – Stack Overflow

Posted by jpluimers on 2020/06/02

I hardly do this, so I tend to forget that unset -f functionname deletes a function and unset variablename or unset -v variablename deletes a variable.

From:

I have done this:bash $ z() { echo ‘hello world’; }How do I get rid of it?

Source: [WayBack] How do I delete a Bash function? – Stack Overflow

Reference: [WayBack] unset Man Page – Bash – SS64.com

–jeroen

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

Force NTP Time Update on Linux | KrazyWorks

Posted by jpluimers on 2020/06/01

A while ago, I had a problem that one of my Raspberry Pi machines hadn’t been turned on for a while, so after a reboot the clock was way off.

This resulted in errors like the below: SEC_ERROR_OCSP_FUTURE_RESPONSE errors indicating the TLS certificates being not yet valid (and numerous other TLS certificate issues).

The /etc/ntp.conf was OK, and rcntpd status indicated the service was running. Looking at /var/log/ntp.log I saw a few syncing issues:

11 Feb 20:04:15 ntpd[1419]: receive: Unexpected origin timestamp 0xde15bc7f.59622c55 does not match aorg 0000000000.00000000 from server@93.94.224.67 xmt 0xde2b122f.0d222048
11 Feb 20:04:15 ntpd[1419]: receive: Unexpected origin timestamp 0xde15bc7f.595fec0e does not match aorg 0000000000.00000000 from server@213.154.236.182 xmt 0xde2b122f.0dc06af7
11 Feb 20:04:15 ntpd[1419]: receive: Unexpected origin timestamp 0xde15bc7f.595d4584 does not match aorg 0000000000.00000000 from server@149.210.199.182 xmt 0xde2b122f.0df70400

My guess was that the time was so much of (more than a month) that syncing would not work, so a manual force was needed.

[Archive.is] Force NTP Time Update on Linux | KrazyWorks provides two solutions:

sntp -r pool.ntp.org
# or
ntpdate -u pool.ntp.org

Only the last one works; I’m not sure why yet:

daisy:/etc # ntpdate -u pool.ntp.org
15 Mar 19:20:59 ntpdate[2516]: step time server 131.211.8.244 offset 4140423.716209 sec

Further reading:

–jeroen

SEC_ERROR_OCSP_FUTURE_RESPONSE

SEC_ERROR_OCSP_FUTURE_RESPONSE

Posted in *nix, *nix-tools, ntpdate, Power User | Leave a Comment »

rrdtool: MRTG next level graphing | Syed Jahanzaib Personal Blog to Share Knowledge !

Posted by jpluimers on 2020/05/29

Even though the below link is to a draft post, it sill provides quite some guidance on how to use RRD graphs in an MRTG environment.

[WayBack] rrdtool: MRTG next level graphing | Syed Jahanzaib Personal Blog to Share Knowledge !

–jeroen

DRAFT VERSION: This is incomplete Post ! Some points may be missing, I will update them later .. We all know what is MRTG. You can graph so many information including temperature humidity, speed, v…

 

Posted in *nix, *nix-tools, Power User | Leave a Comment »

Getting rid of Docker plain text credentials – Hacker Noon

Posted by jpluimers on 2020/05/29

For my research list: [WayBack] Getting rid of Docker plain text credentials – Hacker Noon

Repository at [WayBack] GitHub – docker/docker-credential-helpers

–jeroen

Posted in *nix, *nix-tools, Cloud, Containers, Docker, Infrastructure, Power User | Leave a Comment »

GitHub – dschmenk/apple2pi: Apple II client/server for Raspberry Pi

Posted by jpluimers on 2020/05/28

[WayBack] GitHub – dschmenk/apple2pi: Apple II client/server for Raspberry Pi: hybrid computer of a Raspberry Pi inside an Apple II (either ][, or ][+, or //e) so the Apple II can be a front-end to the Raspberry Pi which then can run an Apple IIGS emulator, talk to the Apple II storage hardware and much more.

It can run [WayBack] RASPPLE II: A2CLOUD, A2SERVER, Apple II Pi for Raspberry Pi

Lot’s of videos below, all by David Schmenk https://www.youtube.com/user/dschmenk/videos

Via:

–jeroen

 

 

Posted in *nix, *nix-tools, //e, 6502, Apple, Apple ][, Development, Hardware Development, Hardware Interfacing, History, Power User, Raspberry Pi, USB | Leave a Comment »

Raspberry Pi 1B OpenSuSE Tumbleweed zypper upgrade problem · GitHub

Posted by jpluimers on 2020/05/25

It looks like OpenSuSE has stopped supporting Raspberry Pi 1, so the best likely is to recycle it into a Pi-Hole as basically it’s been dead since mid 2017: [WayBack] Raspberry Pi 1B OpenSuSE Tumbleweed zypper upgrade problem · GitHub.

Build status for armv6l support: [WayBack] Project openSUSE:Factory:ARM Status Monitor – openSUSE Build Service

–jeroen

Read the rest of this entry »

Posted in *nix, *nix-tools, Debian, Development, Hardware Development, History, Linux, openSuSE, Power User, Raspberry Pi, Raspbian, SuSE Linux, Tumbleweed | Leave a Comment »

David Korn Tells All – Slashdot

Posted by jpluimers on 2020/05/21

Almost 20 years old, but still a very nice read [Archive.is] David Korn Tells All – Slashdot.

Another funny story involving David Korn during the not-so open source times of Microsoft late last century: [WayBack] Korn Shell Story

–jeroen

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

Show openSUSE:Factory / bootchart – openSUSE Build Service

Posted by jpluimers on 2020/05/15

On my research list: [WayBack] Show openSUSE:Factory / bootchart – openSUSE Build Service.

I bumped here when researching on how to list services: [WayBack] init.d – Command to list services that start on startup? – Ask Ubuntu

It seems few people use it on opensuse, but it is interesting for analysing the boot process nonetheless.

I already found out this is in fact bootchart2: [WayBack] GitHub – xrmx/bootchart: merge of bootchart-collector and pybootchartgui

Some links that should help me further are these:

From the last link, this translation:

A. systemd-analyze

You will see the total computer startup time after:

systemd-analyze

A complete list of how much each individual service has taken is when you complete:

systemd-analyze blame

You will see the most problematic processes after you complete:

systemd-analyze critical-chain

You can create a picture:

systemd-analyze plot> /tmp/systemd-analyze.svg

Suitable for: openSUSE 11.4, 12.x, 13.1, Leap 42.x

Not suitable: openSUSE 13.2

B. bootchart

First, install the bootchart package (bootchart 2 version of the program). If you are using openSUSE Leap 42.x or later, enable bootchart2 (and optional bootchart2-done) service:

systemctl enable bootchart2

systemctl enable bootchart2-done

If you are using openSUSE version 13.1 or earlier, go to YaST → (System) → Startup and enter kernel startup parameters:

initcall_debug printk.time = y quiet init = / sbin / bootchartd rdinitrd = / sbin / bootchartd

The next time you start your computer, the /var/log/bootchart.png image will be created to help you further optimize your system startup. For example, if you do not need an AppArmor who cares about security, you can disable the boot.apparmor service through the YaST Service Configuration Module.

Suitable for: openSUSE 11.4, 12.x, 13.1, 13.2, Leap 42.x

–jeroen

Posted in *nix, *nix-tools, Linux, openSuSE, Power User, SuSE Linux, Tumbleweed | Leave a Comment »

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