Miscellaneous Interesting Stuff

Please find here preserved knowledge that does not (yet) deserves its own page or is interdisciplanry so that it would fit in more that one place. This includes topics like...

Charsets

The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)

Charset and Collation Recommendation for MySQL/MariaDB

[client]
default-character-set = utf8mb4

[mysql]
default-character-set = utf8mb4

[mysqld]
character-set-client-handshake = FALSE
collation-server = utf8mb4_unicode_ci
init-connect = 'SET NAMES utf8mb4 COLLATE utf8mb4_unicode_ci'
character-set-server = utf8mb4

Further Reading / Sources:

• utf8 vs. utf8mb4
• MariaDB KB article on Setting Character Sets and Collactions
• https://medium.com/@adamhooper/in-mysql-never-use-utf8-use-utf8mb4-11761243e434
• https://stackoverflow.com/questions/47566730/force-mariadb-clients-to-use-utf8mb4
• How to support full Unicode in MySQL databases by Mathias Bynens

OpenSSH ProxyJump and ProxyCommand

ProxyJump is available since OpenSSH version 7.5. ProxyCommand somewhat longer. The following examples both establish a connection to the remote server by using a jump server as a proxy server in between.

ssh -J user@<jump server> <remote-server>

ssh -o ProxyCommand="ssh -W %h:%p <jump server>" <remote-server>

The ProxyJump even provides fallback:

ssh -J <jump server1>,<jump server2>,<jump server3> <remote-server>

You can put this config into your ~/.ssh/config file:

Host remoteserver
  HostName demo.test.com
  User dev
  IdentityFile ~/.ssh/id_rs
  Port 2048

  ## sample for ProxyJump
  ProxyJump user@jump.test.com

  ## sample for ProxyCommand
  ProxyCommand ssh -W %h:%p user@jump.test.com

See How to Use SSH ProxyJump and SSH ProxyCommand for more details.