epub bookmark update

Origin link 2025-12-7

Dovecot upgrade from 2.3 to 2.4

Origin link 2025-11-18

#dict {
#quota = mysql:/etc/dovecot/dovecot-dict-sql.conf.ext
#expire = sqlite:/etc/dovecot/dovecot-dict-sql.conf.ext
#}
userdb passwd {
          #driver = passwd
}
passdb pam {
          #driver = pam
          passdb_driver=pam
}
#mail_location = mbox:~/mail:INBOX=/var/mail/%u
#mail_location = mbox:~/mail:INBOX=/var/mail/%{user}

mail_driver = mbox
mail_path = ~/mail
mail_inbox_path = /var/mail/%{user}
#ssl_cert = </etc/letsencrypt/live/hongy19.net/fullchain.pem
#ssl_key =  </etc/letsencrypt/live/hongy19.net/privkey.pem
#ssl_dh =   </etc/dovecot/dh.pem
ssl_server_cert_file = /etc/letsencrypt/live/hongy19.net/fullchain.pem
ssl_server_key_file = /etc/letsencrypt/live/hongy19.net/privkey.pem
ssl_server_dh_file = /etc/dovecot/dh.pem

/var/permission

Origin link 2025-11-18

 

from link, /var/mail should have correct permissions 2775 root:mail

The first digit "2" represents the setgid (Set Group ID) special permission:

The s represents the setgid bit. It appears in the group execute position:
  • Normal group permissions: rwx (read, write, execute)
  • With setgid: rws (read, write, setgid)
  • With setgid but no execute: rwS (capital S)

pdflatex + ctex support Chinese font

Origin link 2025-7-20

\documentclass[fontset=none]{ctexart}

\usepackage{CJKutf8}
\begin{document}
\begin{CJK*}{UTF8}{gbsn}
你好，世界！
\end{CJK*}
\end{document}
\documentclass{article}
\usepackage{CJK}
\begin{document}
\begin{CJK}{UTF8}{gbsn}
这是一个CJKutf8的例子，使用的字体是gbsn。
\end{CJK}
\end{document}


wifi error for raspberry: brcmfmac: brcmf_set_channel: set chanspec 0x100e fail, reason -52

Origin link 2024-9-20

 

I couldn't connect to my raspberry pi for several days. Today I conducted a trouble shooting. 

At beginning, I think system is down due to flashcard broken but later I found raspyberry still has ipv4/ipv6 address from home router. I tried to ssh but not successful. I ping the server first, ping is Ok. Then I could ssh server successfully.

it seems i am not the only guy who has this issue, see 

https://forums.raspberrypi.com/viewtopic.php?t=367466

https://askubuntu.com/questions/1508490/ubuntu-server-on-raspberry-pi-5-is-not-connecting-to-the-internet

python typing check

Origin link 2024-8-1

racket

Origin link 2024-3-17

 racket is one of scheme dialect and I want to use racket to learn "the litte schemer". One of problem I meet is how to load file with scheme code (not racket code) into REPL and run relate function. In guile, it is very simple: guile -l my_function.scm. but in racket, it is little complex.

 it could work "racket -if <my_function.scm>" but my_function.scm should not start with "#lang racket". it is same with load function. 
Racket has concept of module, every file is module and each module need "initial-module-path" which is "The #lang at the start of a module file begins a shorthand for a module form"

First, like import in python, you could use (require my_function.scm) in source code and "-t " in command line to import a module, but you need to list which function is export by (provide function) in my_function.scm, or (provide (all-defined-out)) to export all functions. 

 -t <file>, --require <file> Like -e '(require (file "<file>"))' [*]

Another trick point is you need "racket -i -t my_function.scm" instead of "racket -t  my_function.scm -i". I don't know why but I guess it is related to "If -t/-l/-p/-u appears before the first -i/-e/-f/-r, -n is added".

Second, you could config initial-module in command line with "racket -I typed/racket" (#lang typed/racket in source code). The magic of of initial-module-path is you could define a new language with different syntax.

Third, you could always start "racket -i" and use ",enter my_function.scm" or "racket -i -e '(enter! "my_function.scm")'" to go to my_function namespace.

git remote repository with bare

Origin link 2023-12-1

 if you want a remote repository and put local source into remote, you need to set up remote repository with  "git init bare . ", not "git init ."

link1, link2


xmlrpc on rtorrent

Origin link 2023-11-24

rotorrent could use xmlrpc to send command remotely without any ui interface.

WSL with gpu accelerator and webgpu

Origin link 2023-11-24

GPU accelerator on WSL need WDDM 2.9 (link ). Windows 10 support WDDM from 20H2 (link) but Intel driver only support WDDM > 2.9 from Windows 11 (link). You could use "dxdiag" to check WDDM version on your windows.

My laptop is Intel GPU + Windows 10. Intel driver doesn't support WDDM v2.9 or later on Windows 10 but it is OK on Windows 11. It means WSL couldn't support GPU accelerator on Windows 10.

If you want to use webgpu under wsl2, use following chrome command since webgpu on chrome only support vulkan now according to Chrome ships WebGPU. 






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