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

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Archive for the ‘Linux’ Category

Some links on bind rndc

Posted by jpluimers on 2020/03/13

No, this is not a random number generator, according to the documentation, bind rndc is the name server control utility. Again very undescriptive; luckily the full name found elsewhere is Remote Name Daemon Control.

Some links for my archive as often there are no man-pages installed on systems with bind:

–jeroen

Posted in *nix, bind-named, Linux, Power User | Leave a Comment »

I love installers that can download and install in parallel threads….

Posted by jpluimers on 2020/02/04

[WayBack] I love installers that can download and install in parallel threads. Embarcadero and Zypper can learn from this. – Jeroen Wiert Pluimers – Google+

Most Linux distributions have package managers that can do this (apt and yum can), but OpenSuSE zypper (actually ZYpp) cannot even download packages in parallel:

Embarcadero is in the same state as zypper.

–jeroen

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

TL;DR: Raspberry Pi models 1..3 become hotter and hotter under load; no housing gives best cooling.

Posted by jpluimers on 2020/02/04

[WayBack] TIL Raspi Kühlkörper bringen nix. Lego schon.  – Kristian Köhntopp – Google+

Background information: [Archive.is] Mein Raspberry Pi 3 und sein Problem mit der Systemtemperatur · Un*xe

–jeroen

 

Posted in *nix, Debian, Development, Hardware, Hardware Development, Linux, Power User, Raspberry Pi, Raspbian | Leave a Comment »

OpenSuSE: location of cron jobs

Posted by jpluimers on 2020/01/20

When you look at how to find listed cron jobs, usually the answer is cron -l or cron -u username -l.

However, on OpenSuSE systems, cron jobs can be in different places, and the sysconfig settings have influence on them too.

These files and directories all influence cron:

Directories:

/etc/cron.d/
/etc/cron.daily/
/etc/cron.hourly/
/etc/cron.monthly/
/etc/cron.weekly/

Files:

/etc/sysconfig/cron
/etc/init.d/rc2.d/K01cron
/etc/init.d/rc2.d/S14cron
/etc/init.d/rc3.d/K01cron
/etc/init.d/rc3.d/S14cron
/etc/init.d/rc5.d/K01cron
/etc/init.d/rc5.d/S14cron
/etc/init.d/cron
/etc/news/crontab.sample
/etc/pam.d/crond
/etc/systemd/system/multi-user.target.wants/cron.service
/etc/omc/srvinfo.d/cron.xml
/etc/cron.deny
/etc/crontab

Most are available for other Linux distributions as well, but each one might have slightly different configurations (especially for the directories). Some background reading:

Some details:

  • The crontab -l will only list what is in /etc/crontab.
  • These directories are influenced by/etc/sysconfig/cron, especially the DAILY_TIME variable (see below) for the daily jobs.
    All of the directories are checked every 15 minutes through /usr/lib/cron/run-crons:/etc/cron.daily/
    /etc/cron.hourly/
    /etc/cron.monthly/
    /etc/cron.weekly/
  • That script then uses these files for checking when to run:/var/spool/cron/lastrun/cron.weekly
    /var/spool/cron/lastrun/cron.daily
    /var/spool/cron/lastrun/cron.hourly

The DAILY_TIME variable:

## Type: string
## Default: ""
#
# At which time cron.daily should start. Default is 15 minutes after booting
# the system. Example setting would be "14:00".
# Due to the fact that cron script runs only every 15 minutes,
# it will only run on xx:00, xx:15, xx:30, xx:45, not at the accurate time
# you set.
DAILY_TIME=""

–jeroen

 

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

a perf cheat sheet from @brendangregg’s fantastic web page;  you can print it as PDF

Posted by jpluimers on 2020/01/13

From a while back: [WayBack⚡Julia Evans⚡ on Twitter : made a perf cheat sheet from @brendangregg’s fantastic https://t.co/SBDtzn0G8J. you can print it at https://t.co/xC6ndjrSDL https://t.co/TstbBBe3DS

References:

The latter has a lot of examples and even more explanation all around the below picture.

–jeroen

Read the rest of this entry »

Posted in *nix, *nix-tools, Development, Linux, Power User, Profiling-Performance-Measurement | Leave a Comment »

 
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