• Kernel-Tuning
• Read HFS+ Partition
• Multimedia
• Create Swap File
• PowerDNS via Apache2 with PostgreSQL on Debian and PowerDNS-Admin
• lemur and cfssl with NGINX and PostgreSQL on CentOS8
• File Watcher Service
• tmux
• systemd

rsync -vr /home/user/important_directory /media/some_hdd/backups/

Hint: With a / at the end of the first directory, all sub directories are copied directly to the destination folder. Without / it will create the source folder (ex. important_directory) with all sub directories are copied to the destination folder

You have a server for example and some mails are sent directly to root. The easiest way to forward them to a real address ist to create a .forward file.

/root/.forward

user@example.org
 

Immportant: The last line of the file have to be empty. It won't work without newline.

Misconfiguration may result in following log lines of your mail server:

Jul  6 10:10:48 myHostName postfix/cleanup[362]: 4E14342D46: message-id=<20140706081048.4E14342D46@mail.example.org>
Jul  6 10:10:48 myHostName postfix/qmgr[24720]: 4E14342D46: from=<>, size=2540, nrcpt=1 (queue active)
Jul  6 10:10:48 myHostName postfix/bounce[368]: 3D46942C3D: sender non-delivery notification: 4E14342D46
Jul  6 10:10:48 myHostName postfix/smtp[367]: 4E14342D46: to=<root@mail.example.org>, relay=none, delay=0.04, delays=0.01/0/0.03/0, dsn=5.4.6, status=bounced (mail for mail.example.org loops back to myself)
Jul  6 10:10:48 myHostName postfix/qmgr[24720]: 4E14342D46: removed

xmllint --schema schema.xsd --noout file.xml

or

xmlstarlet val -s schema.xsd -e file.xml

• Stdout Buffering
• Measuring context switching and memory overheads for Linux threads
• How to Check Disk Queue Length in Linux