sysfs

Read the required files in a directory.

Function Arguments

Name	Type	Description
dir_path	str	The path of target sysfs folder.
keys	list	The required file names in the sysfs folder.
optional_keys	list, None	(optional; default: None) The optional file names in the sysfs folder.

Description

Sysfs exports the information of device to a directory, and each attribute is stored in a separate file. This function is aimed to read the structure.

Examples

Let’s say we have the file tree:

• /sys/bus/cool/devices/1/aa contains “A”

• /sys/bus/cool/devices/2/aa contains “AA”

• /sys/bus/cool/devices/2/bb contains “BB”

• /sys/bus/cool/devices/3/xx contains “XX”

And the probe statement is:

{
  "eval": {
    "sysfs": {
      "dir_path": "/sys/bus/cool/devices/*",
      "keys": [
        "aa"
      ],
      "optional_keys": [
        "bb"
      ]
    }
  }
}

Then the probed results are:

[
  {
    "aa": "A"
  },
  {
    "aa": "AA",
    "bb": "BB"
  }
]

The probed results don’t include the entry /sys/bus/cool/devices/3 because that entry doesn’t contain the required field aa.