bellow is a simple script, i use to record dpm data in the background:

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#!/bin/bash

# adapt this sample inverval (seconds)
SLEEP_INTERVAL=0.05

# adapt the paths to your need
FILE_SCLK=/sys/class/drm/card0/device/hwmon/hwmon0/freq1_input
FILE_MCLK=/sys/class/drm/card0/device/hwmon/hwmon0/freq2_input
FILE_PWM=/sys/class/drm/card0/device/hwmon/hwmon0/pwm1
FILE_TEMP=/sys/class/drm/card0/device/hwmon/hwmon0/temp1_input
FILE_FAN=/sys/class/drm/card0/device/hwmon/hwmon0/fan1_input
FILE_GFXVDD=/sys/class/drm/card0/device/hwmon/hwmon0/in0_input
FILE_POW=/sys/class/drm/card0/device/hwmon/hwmon0/power1_average
FILE_BUS=/sys/class/drm/card0/device/gpu_busy_percent

# checking for privileges
if [ $UID -ne 0 ]
then
  echo "Writing to sysfs requires privileges, relaunch as root"
  exit 1
fi

function read_output {

  SCLK=$(cat $FILE_SCLK)
  MCLK=$(cat $FILE_MCLK)
  TEMP=$(cat $FILE_TEMP)
  FAN=$(cat $FILE_FAN)
  GFXVDD=$(cat $FILE_GFXVDD)
  POW=$(cat $FILE_POW)
  BUS=$(cat $FILE_BUS)

#  echo "sclk: $SCLK mclk: $MCLK gfx_vdd: $GFXVDD"
  echo "sclk: $SCLK mclk: $MCLK temp: $TEMP fan: $FAN gfx_vdd: $GFXVDD pow:
$POW bus: $BUS"
}

function run_daemon {
  while :; do
    read_output
    sleep $SLEEP_INTERVAL
  done
}

# finally start the loop
run_daemon

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