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POSIX semaphore 1. Basic concepts The logic of POSIX semaphore is exactly the same as that of semaphore elements in IPC semaphore group, but the operation of POSIX semaphore is simpler and the interface is easier to use. It is widely used in multi process and multi thread. POSIX semaphores are divided into two types: POSIX anonymous sema ...

Error code: ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'exit()' at line 1 　　or ERROR 1396 (HY000): Operation ALTER USER failed for 'root'@'localhost' 　　or ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using pa ...

The virtual file system is VFS, and the kernel provides file and file related interfaces. All files in the system not only depend on VFS coexistence, but also rely on VFS coordination. Common file interfaces, including read, write and open, can be used to read files and hard disks. The reason why a unified interface can be used to read an ...

1, Introduction to Zabbix monitoring 1.1 Zabbix monitoring architecture In order to prevent Zabbix single point of failure, Zabbix high availability is made. If the company cluster is not large, a single machine can be used;If there are too many agents, you need a Proxy to reduce the pressure on Zabbix;The data is stored in the databa ...

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outline fio is a very flexible io testing tool. It can simulate various io operations through multiple threads or processes With the development of block devices, especially the emergence of SSD disks, the parallelism of devices is becoming higher and higher. To make good use of these devices, a trick is to improve the iodepth of the device, ...

file module The keywords of this module include path, path of the controlled host, state status, touch to create file, directory to create directory, recursion, owner's master, group, and mode permission. 1. Create a file and set the owner, group and permission [root@localhost opt]# ansible dbserver -m file -a "path=/var/www/html/xjm.html st ...

1. Common system monitoring commands 1.1 problems In this case, you are required to be familiar with the common commands for viewing the Linux system status and prepare for further specific monitoring tasks: View memory informationView swap partition informationView disk informationView CPU InformationView network card informationView ...

Linux Process IntroductionIf you want to write a small program for calculating addition, the program needs to input from one file, and the results after calculation are input into another file.Because the computer only knows 0 and 1, no matter which language is used to write this code, it needs to be translated into binary files in some way in ...

preface Now, in our daily development or production environment, we often get a set of automatic deployment scheme to save time and cost. A popular implementation scheme is Gitlab+Jenkins, but this scheme still occupies a large memory and needs about 8G of server memory. Otherwise, it is difficult to run smoothly and deploy quickly. Recently, ...