Linux Tips

 To install development tools on CentOS7, generally use the following command. yum groupinstall "Development Tools" However, RedHat or CentOS Linux tends to prefer older packages with proven stability over newer ones. Therefore, package versions are often lower than Ubuntu. If you check the version after installing gcc, it is 4.8.5. [ root@localhost ~ ] # gcc --version gcc ( GCC ) 4.8.5 20150623 ( Red Hat 4.8.5-36 ) Copyright ( C ) 2015 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. However, sometimes you need to upgrade your gcc or g++ version to build a package that requires the latest c++(for exasmple c++ 14) syntax. However, it is impossible to upgrade gcc to a higher version with yum update. You will have to build the source code or find another way to install it. Install The Software Collections ( SCL ) Repository first....

 The disk of my Ubuntu 20.04 used for development was originally 20Gb, and I increased it to 30GB a while ago. This time, the capacity was insufficient again, so I increased it to 50 GB. Every time I did this work, I had a hard time, so I'm going to leave it as a simple post so that I don't repeat the trouble afterwards. The following is a disk with 30 GB status. The usage is 50%. However, this is because there was not enough disk and the files were temporarily moved to another location. After increasing the disk capacity, the backed up files will be imported again. root@ubuntusrv:~# df -h Filesystem Size Used Avail Use% Mounted on udev 937M 0 937M 0% /dev tmpfs 196M 1.3M 195M 1% /run /dev/mapper/ubuntu--vg-ubuntu--lv 29G 14G 14G 50% / tmpfs 980M 0 980M 0% /dev/shm tmpfs 5.0M 0 5.0M 0% /run/lock tmpfs ...

 There are several ways to manage processes on a Linux system. Most important processes are managed as daemon processes. However, since the daemon process is only a process whose parent process is init (pid = 1), the service provided by the process is terminated when abnormally terminated. Therefore, many IT system administrators monitor critical processes. For such monitoring, management tools such as Zabbix are sometimes used. Zabbix can monitor networks, servers, virtual machines and cloud services, and it can even automatically trigger an alarm when a number that exceeds the limits set by the administrator is detected.  While managing these large systems is important, monitoring critical processes on smaller servers and automatically restarting them upon specified shutdown is equally important. monit is a great tool to do this. It is easy to install and very light compared to packages such as Zabbix. Note that monit only works on the server where the pa...

What is RAM Disk? A RAM drive (also called a RAM disk) is a block of random-access memory (primary storage or volatile memory) that a computer's software is treating as if the memory were a disk drive (secondary storage). It is sometimes referred to as a virtual RAM drive or software RAM drive to distinguish it from a hardware RAM drive that uses separate hardware containing RAM, which is a type of battery-backed solid-state drive.   From WikiPedia There are several reasons to use ram disks on the Raspberry Pi.  The Raspberry Pi uses a MicroSD card as a storage device. SD cards have a fixed write life. If you write more than a certain number of times, the life of the SD card will end. This phenomenon is the same for SSDs. To prevent this, you can use a large-capacity SD card. However, if you have to use a low-capacity SD card of 8GB to 16GB due to problems such as cost, excessive write operations shorten the lifespan of the SD card. RamDisk is worth considering if you are...

 Recently, Microsoft provides ODBC client S/W for Linux that can connect to its MSSQL. This Linux client S/W can be used in almost all distributions such as CentOS, RedHat, Ubuntu, Debian, and SUSE. However, all of these client modules for MS SQL are for x86 (amd64). Therefore, it cannot be used in Raspberry Pi (Debian distribution) and NVidia Jetson series (Ubuntu distribution) using ARM CPU. Therefore, you should use FreeTDS modules previously provided by the open source community. The following is an introduction to freetds.org/. F reeTDS is a set of libraries for Unix and Linux that allows your programs to natively talk to Microsoft SQL Server and Sybase databases. T echnically speaking, FreeTDS is an open source implementation of the TDS (Tabular Data Stream) protocol used by these databases for their own clients. It supports many different flavors of the protocol and three APIs to access it. Additionally FreeTDS works with other software such as Perl and PHP, provi...