Running a nightly backup script on a server system, such as a web hosting server, can result in a heavy load and longer latency for other processes, for example, HTML or .php pages load slowly during the backup because the backup script requires too many I/O or CPU resources. On Linux systems, two shell utilities ... Read more
In this short article, I explain how to disable IPv6 in the Debian 10 network stack. Why would one want to do this? Most likely if you have connection problems and cannot reach servers on the Internet from your Debian system using IPv6, while it works using IPv4. Disabling IPv6 should always be the last ... Read more
The following command can be used to check and repair all MySQL databases on a Ubuntu or Debian Linux System. I've tested the commands on Ubuntu 20.04 and Debian 10. Repair MySQL databases on Ubuntu Linux sudo mysqlcheck --defaults-file=/etc/mysql/debian.cnf --auto-repair --optimize --all-databases MySQL database repair on Debian mysqlcheck --defaults-file=/etc/mysql/debian.cnf --auto-repair --optimize --all-databases The benefit of ... Read more
JPEG is a lossy compression file format for digital images. It can greatly reduce the amount of storage space used by a graphics file compared to the PNG format. This tutorial describes how to convert a PNG file to JPG on the shell. I use the GraphicsMagick command-line tool on my Ubuntu 20.04 system to ... Read more
The ps command in Linux, as you might already know, is one of the most frequently used command-line tools. For the uninitiated, the utility basically reports a snapshot of the current processes on the system. The ps command provides a plethora of options, and as you might agree, it's not possible to know about or ... Read more
When you get the error message "system-config-firewall: command not found" on your CentOS Server while trying to configure the firewall on the shell, then the text interface version of the firewall configuration utility is missing. Install CentOS Firewall configuration tool Install it with this command: yum install system-config-firewall-tui
The current status of a Linux software raid is written to the virtual file /proc/mdstat. You can view the status on the shell easily with the cat command: cat /proc/mdstat The output will look similar to this: Personalities : [raid0] [raid1] [raid6] [raid5] [raid4] md2 : active raid1 sda3[0] sdb3[1] 726266432 blocks [2/2] [UU] md1 ... Read more
If a process is shown with process state "D" in tools like ps or top, then it's an uninterruptable process. Example: ps axl | grep D F UID PID PPID PRI NI VSZ RSS WCHAN STAT TTY TIME COMMAND 4 104 2579 9109 20 0 5024 2116 refrig D ? 0:00 cleanup -z -t unix ... Read more
This short tutorial describes the steps to optimize the performance of a MySQL database with the mysqltuner script. This tool can be used for MySQL and MariaDB. Install mysqltuner The mysqltuner High-Performance MySQL Tuning Script is available as a package on Debian 10 and Ubuntu 20.04, install it with at: sudo apt install mysqltuner For ... Read more
Sometimes you might want to block connects to your server by IP address. E.g. when someone tries to attack your system. This can be done in several different ways, e.g. with iptables (firewall) rules or by setting up a reject route. Reject access with Linux route command Using iptables sometimes causes conflicts with installed firewalls ... Read more