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# RANDOM LINUX TIPS & TRICKS

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# Get INFO/VERSION

# Raspberry PI model / revision / serial

# SN#:

# 10000000XXXXXXXX

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# Kernel version

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# fedora update kernel/system

# For example, to add the user linuxize to the sudo group you would run the following command:

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# Configure to boot into Raspbian Desktop

# use your arrow keys to navigate to Enable Boot to Desktop and press enter. Select the Desktop login option and press enter.

# Configure to boot into Raspbian Desktop (without raspi-config)

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# Raspberry testing repository

# replace buster by testing in /etc/apt/sources.list

# # from
# deb http://raspbian.raspberrypi.org/raspbian/ buster main contrib non-free rpi
# # to
# deb http://raspbian.raspberrypi.org/raspbian/ bullseye main contrib non-free rpi

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# check if process is locked

# kill process (replace pid_id by the process ID number)

# check if killed

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# Disable DEBIAN 10 GUI:

To re-enable the GUI:

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# activate raspberry pi WIFI

# Select “Localisation Options” then select “change WLAN country”

# then enter root

# generate wpa_passphrase using your SSID and followed by typing the wifi password
# replace YOUR-SSID by the exact name of your wifi network name

# check if the configuration is okay

# should contain something like this:
# the country= must contains a 2 letters ISO 3166-1 of your country code

# network IP info

# scan wifi network

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# power OFF / ON HDMI raspberry pi

# hdmi OFF

# hdmi ON

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# AMD64 Useful Cmds

# get hostname

# set hostname

127.0.0.1 localhost
127.0.1.1 musiclounge

# The following lines are desirable for IPv6 capable hosts
::1 localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

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# Check your current Ethernet connection speed

# install ethtool utility

# determine the name of your ethernet interface usually eth0 or enp3s0

# get the speed

# get current playback info useful to check if current playback is DSD native (DSD_U32_BE)

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# in case you have to entry commands from the server console and not from remote PC/SSH session
# you may want to change the keyboard layout
# use the followinf cmd on debian

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Manage USB Power State (Enable Auto-suspend) of DAC

On Linux (including Debian), it is possible to manage USB power states or disconnect a USB device programmatically or automatically after a period of inactivity. Here’s how you can approach this using a Topping D50 III DAC as an example:

List devices attached and identify your DAC:

lsusb

Bus 001 Device 003: ID 152a:8750 Thesycon Systemsoftware & Consulting GmbH D50 III

The device 152a:8750 (Thesycon Systemsoftware & Consulting GmbH D50 III) can be managed using the USB power management options in Linux. Below is a step-by-step guide specific to this device.

ls /sys/bus/usb/devices/

1-0:1.0 1-1:1.0 1-1:1.2 2-0:1.0 4-0:1.0 usb2 usb4
1-1 1-1:1.1 1-1:1.3 3-0:1.0 usb1 usb3

udevadm info -q path -n /dev/bus/usb/001/003

/devices/platform/axi/1000120000.pcie/1f00200000.usb/xhci-hcd.0/usb1/1-1

Based on the `udevadm` output, the USB device is associated with the path `/devices/platform/axi/1000120000.pcie/1f00200000.usb/xhci-hcd.0/usb1/1-1`, which maps to the `1-1` directory in `/sys/bus/usb/devices/`. Here’s how to manage power settings for this device:

Step 1: Verify Device Directory

The device directory is /sys/bus/usb/devices/1-1.

1. Navigate to the directory to confirm it exists:

   cd /sys/bus/usb/devices/1-1
   ls

You should see files like power, idVendor, and idProduct, which indicate it’s the correct USB device.

2. Confirm the device ID matches 152a:8750:

   cat idVendor
   cat idProduct

Ensure idVendor is 152a and idProduct is 8750.

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Step 2: Enable Autosuspend

1. Check the current power management state:

   cat power/control

If it says on, the device is not suspending.

2. Enable autosuspend:

   echo 'auto' | sudo tee power/control

3. Set the autosuspend delay (e.g., 60 seconds):

   echo '60000' | sudo tee power/autosuspend_delay_ms

These settings will allow the device to enter a low-power state after 60 seconds of inactivity.

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Step 3: Automate with udev Rules

To make the changes persistent:

1. Create a udev rules file:

   sudo nano /etc/udev/rules.d/99-usb-autosuspend.rules

2. Add the following content (in the first line of the file):

ACTION=="add", SUBSYSTEM=="usb", ATTR{idVendor}=="152a", ATTR{idProduct}=="8750", ATTR{power/control}="auto", ATTR{power/autosuspend_delay_ms}="5000"

# CTRL+X to save

3. Reload udev rules:

   sudo udevadm control --reload-rules
   sudo udevadm trigger --subsystem-match=usb

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Step 4: Disable/Enable the Device Manually

1. Disable the device:

   echo '0' | sudo tee authorized

2. Re-enable the device:

   echo '1' | sudo tee authorized

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Step 5: Test the Configuration

1. Monitor power state:

   cat power/runtime_status

You should see suspended when the device is in a low-power state.

2. Verify the autosuspend delay:

   cat power/autosuspend_delay_ms

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Troubleshooting

• If the device does not suspend, check if it supports USB autosuspend. Some devices might not fully adhere to the USB power management specifications.
• Review logs for errors:

   dmesg | grep usb