Detailed explanation and example analysis of sysfs related API
In Linux systems, the virtual file system under the /sys directory provides a flexible interface that allows users to interact with kernel devices and drivers. This interface is called sysfs, which allows user space applications to control and monitor various attributes of the kernel by reading and writing files. This article will introduce sysfs-related APIs in detail and analyze them with examples.
1. Sysfs directory structure
The file system under the /sys directory contains a large number of virtual files and directories, and its structure is as follows:
/sys/
├── block/
├── bus/
├── class/
├── dev/
├── devices/
├── firmware/
├── fs/
├── hypervisor/
├── kernel/
├── module/
├── power/
├── security/
├── sys/
└── virt/
Each subdirectory corresponds to a kernel object, such as block/ is used to describe block devices, class/ is used to describe all device classes, dev/ is used to describe all character and block devices, and so on.
Two, sysfs API
The sysfs API includes the following commonly used functions:
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int sysfs_create_file(struct kobject *kobj, const struct attribute *attr);
This function is used to create a file in the sysfs file system, where kobj represents the kernel object to create the file, and attr represents the attribute of the file. -
void sysfs_remove_file(struct kobject *kobj, const struct attribute *attr);
This function is used to delete a file from the sysfs file system, where kobj represents the kernel object of the file to be deleted, at