oe7drt-website/content/notes/archlinux/index.md

---
title: Archlinux
date: 2023-11-29T20:33:48+0100
lastmod: 2024-09-28T23:48:06+0000
tags:
  - archlinux
  - systemd

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---

Arch Linux

## Systemd Unit files

A nice and informative article about unit files.

<https://www.digitalocean.com/community/tutorials/understanding-systemd-units-and-unit-files>

## Unlock locked user accounts

If your user account is locked, wait 15 minutes (usually) and you can try again.

If you need to unlock your account immediately: run this command (if you have another user
that can login on the box):

```console
$ sudo faillock --user dominic --reset
```

Calling `faillock` without arguments show an overview.

## Predictable network interfaces

Get back the "old" interface names like `eth0` or `wlan0` with
{{< man systemd.link 5 >}}.

### Ethernet

This makes my ethernet interface be called **eth0** again.

Create `/usr/lib/systemd/network/80-ether.link` with this content:

```systemd
[Match]
Type=ether

[Link]
NamePolicy=keep kernel
```

Reboot.

### Wireless

This makes my wireless interface be called **wlan0** again.

Create `/usr/lib/systemd/network/80-wlan.link` with this content:

```systemd
[Match]
Type=wlan

[Link]
NamePolicy=keep kernel
```

Reboot.

## Setup WiFi networks

### Using **iwctl**

```console
$ iwctl device list
$ iwctl station wlan0 scan
$ iwctl station wlan0 get-networks
$ iwctl station wlan0 connect {ssid}
```

### Using **nmcli** (NetworkManager)

```console
$ nmcli device wifi list
$ nmcli device wifi rescan
$ nmcli device wifi connect {ssid} --ask
$ nmcli device wifi show-password
```

Last command shows the connected SSID and a QR-code within the terminal.

## Using NetworkManager

We create some files in `/etc/NetworkManager/conf.d`:

## Using `iwd` as the WiFi backend

`wifi_backend.conf`:

```ini
[device]
wifi.backend=iwd
```

## Using `dhcpcd` as DHCP client

`dhcp-client.conf`:

```ini
[main]
dhcp=dhcpcd
```

## Using the CPU with hashcat

```console
$ hashcat -I
hashcat (v6.2.6) starting in backend information mode

OpenCL Info:
============

OpenCL Platform ID #1
  Vendor..: Intel(R) Corporation
  Name....: Intel(R) OpenCL Graphics
  Version.: OpenCL 3.0

  Backend Device ID #1
    Type...........: GPU
    Vendor.ID......: 8
    Vendor.........: Intel(R) Corporation
    Name...........: Intel(R) UHD Graphics 620
    Version........: OpenCL 3.0 NEO
    Processor(s)...: 24
    Clock..........: 1150
    Memory.Total...: 14368 MB (limited to 2047 MB allocatable in one block)
    Memory.Free....: 7136 MB
    Local.Memory...: 64 KB
    OpenCL.Version.: OpenCL C 1.2
    Driver.Version.: 24.31.30508
```

This is what I've seen on `hashcat -I` for a long time now but I never dig myself
into this "problem" -- but today I tried to find the reason why there is no CPU
listed on my Carbon X1 Gen7 laptop.

After a few minutes doing some trial & error I finally got the CPU listed after
installing _pocl_.

```console
$ paru -S pocl
```

Or, on my gaming laptop running a cheap clone of Ubuntu:

```console
$ sudo apt install pocl-opencl-icd
```

Now my `hashcat -I` looks like this:

```console
$ hashcat -I                                                                                                                                        took 6s
hashcat (v6.2.6) starting in backend information mode

OpenCL Info:
============

OpenCL Platform ID #1
  Vendor..: Intel(R) Corporation
  Name....: Intel(R) OpenCL Graphics
  Version.: OpenCL 3.0

  Backend Device ID #1
    Type...........: GPU
    Vendor.ID......: 8
    Vendor.........: Intel(R) Corporation
    Name...........: Intel(R) UHD Graphics 620
    Version........: OpenCL 3.0 NEO
    Processor(s)...: 24
    Clock..........: 1150
    Memory.Total...: 14368 MB (limited to 2047 MB allocatable in one block)
    Memory.Free....: 7136 MB
    Local.Memory...: 64 KB
    OpenCL.Version.: OpenCL C 1.2
    Driver.Version.: 24.31.30508

OpenCL Platform ID #2
  Vendor..: The pocl project
  Name....: Portable Computing Language
  Version.: OpenCL 3.0 PoCL 6.0  Linux, Release, RELOC, LLVM 18.1.8, SLEEF, DISTRO, POCL_DEBUG

  Backend Device ID #2
    Type...........: CPU
    Vendor.ID......: 128
    Vendor.........: GenuineIntel
    Name...........: cpu-haswell-Intel(R) Core(TM) i7-8665U CPU @ 1.90GHz
    Version........: OpenCL 3.0 PoCL HSTR: cpu-x86_64-pc-linux-gnu-haswell
    Processor(s)...: 8
    Clock..........: 4800
    Memory.Total...: 13716 MB (limited to 2048 MB allocatable in one block)
    Memory.Free....: 6826 MB
    Local.Memory...: 256 KB
    OpenCL.Version.: OpenCL C 1.2 PoCL
    Driver.Version.: 6.0
```

## Paru / Pacman

Found on [andreas-mausch.de](https://cheatsheets.andreas-mausch.de/paru) and
I had to copy this to my notes archive here...

<!-- paru start -->

### Install

#### install

```console
$ paru -S <package>
```

#### Edit PKGBUILD and skip checksum check

```console
$ paru -S gnucash-xbt --fm helix --mflags "--skipchecksums"
```

#### uninstall (-n: no backup files; -s: remove dependencies)

```console
$ paru -Rns <package>
```

#### system update

```console
$ paru -Syu
```

### Mirrors

#### select fastest

```console
$ sudo pacman-mirrors --fasttrack
```

#### select by country

```console
$ sudo pacman-mirrors --country Germany,France,Austria
```

### Search repo

#### search package

```console
$ paru -Ss <package>
```

#### package details

```console
$ paru -Si <package>
```

#### list files

```console
$ paru -Fl <package>
```

#### find package for file

```console
$ pkgfile <filename>
```

#### search command

```console
$ paru -F glxinfo
```

### Installed packages

#### search package

```console
$ paru -Qs <package>
```

#### package details

```console
$ paru -Qii <package>
```

#### list files

```console
$ paru -Ql <package>
```

#### orphans

```console
$ paru -Qdt
```

#### manually installed (list all aur)

```console
$ pacman -Qm
```

### Clean-up

#### clear cache

```console
$ paru -Sc
```

### Official repo vs. AUR

#### repo

```console
$ paru -[...] --repo
```

#### aur

```console
$ paru -[...] --aur
```

<!-- paru end -->

## Blocking IPs from a list with ipset

Using [ipset](https://wiki.archlinux.org/title/Ipset) should increase performance
on the box, also using the raw table should not create useless states as for what
I understand from the source article on
[serverfault.com](https://serverfault.com/a/823336).

```console
$ sudo ipset -N badips iphash
$ while read ip; do sudo ipset -A badips "$ip"; done < blocked.txt
$ sudo iptables -t raw -I PREROUTING -m set --match-set badips src,dst -j DROP
$ sudo iptables-save -f /etc/iptables/iptables.rules
```

Enable iptables in case it is not running yet.

```console
$ sudo systemctl enable --now iptables.service
```

Also make the ipset configuration persistent:

```console
$ sudo ipset save -file /etc/ipset.conf
$ sudo systemctl enable ipset.service
```

Reboot to test its persistency.

## Do not manage one specific USB dongle

`99-unmanaged-devices.conf`:

```ini
[keyfile]
unmanaged-devices=mac:xx:xx:xx:xx:xx:xx
```

## Prefer local DNS instead of systemd-resolved defaults

<https://unix.stackexchange.com/a/442599>

## CPU frequency scaling

<https://wiki.archlinux.org/title/CPU_frequency_scaling>

## YubiKeys

<https://wiki.archlinux.org/title/YubiKey>

## LunarVim custom key mappings

I know, this is an Arch Linux post but hey, I don't care.

<https://github.com/LunarVim/LunarVim/issues/2602>

## Mounting nfs shares with systemd

<https://wiki.archlinux.org/title/NFS#Mount_using_/etc/fstab_with_systemd>

## Arch Linux ARM installation on a Raspberry Pi 2

The wiki page is for Raspberry Pi 4.

<https://archlinuxarm.org/platforms/armv8/broadcom/raspberry-pi-4>

## Create a 32-bit Wine prefix

I create my wine prefixes usually like this:

```console
$ export WINEPREFIX=/home/dominic/.wine-winlink
$ export WINEARCH=win32
$ wine wineboot
```

## Installing multiple ruby versions

I came to the point to test an older website from me and it was made with
Jekyll which I had to install quickly. Problems occured with OpenSSL and I
finally managed to install ruby version 2.7.1 and 3.0.0 in my home directory.

```console
$ rvm pkg install openssl
$ rvm install "ruby-3.0.0" --with-openssl-dir=$HOME/.rvm/usr
$ rvm install "ruby-2.7.1" --with-openssl-dir=$HOME/.rvm/usr
```

Later in the desired directory, I re-installed the gems because with ruby 2.7.1
I got another "Directory not found" error.

I had to do this because I used ruby 2.7.1 on one website.

```console
$ bundle install --force
```

## Bigger font for systemd-boot

Edit `/boot/loader/loader.conf`:

```
console-mode 0
```

Possible settings are:

| Value | Description                                                         |
| :---- | :------------------------------------------------------------------ |
| 0     | Standard UEFI 80x25 mode                                            |
| 1     | 80x50 mode, not supported by all devices                            |
| 2     | the first non-standard mode provided by the device firmware, if any |
| auto  | Pick a suitable mode automatically using heuristics                 |
| max   | Pick the highest-numbered available mode                            |
| keep  | Keep the mode selected by firmware (the default)                    |

More details can be found in {{< man loader.conf 5 >}}.

## Manual sections

| Section | Description                                                                                                                                                                                                                                                                                                                                                                                                                          |
| :------ | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 1       | Section 1 of the manual describes **user commands** and tools, for example, file manipulation tools, shells, compilers, web browsers, file and image viewers and editors, and so on                                                                                                                                                                                                                                                  |
| 2       | Section 2 of the manual describes the Linux **system calls**. A system call is an entry point into the Linux kernel. Usually, system calls are not invoked directly: instead, most system calls have corresponding C library wrapper functions which perform the steps required (e.g., trapping to kernel mode) in order to invoke the system call. Thus, making a system call looks the same as invoking a normal library function. |
| 3       | Section 3 of the manual describes all **library functions** excluding the library functions (system call wrappers) described in Section 2, which implement system calls.                                                                                                                                                                                                                                                             |
| 4       | Section 4 of the manual describes **special files (devices)**.                                                                                                                                                                                                                                                                                                                                                                       |
| 5       | Section 5 of the manual describes various **file formats**, as well as the **corresponding C structures**, if any.                                                                                                                                                                                                                                                                                                                   |
| 6       | Section 6 of the manual describes the **games** and funny little programs available on the system.                                                                                                                                                                                                                                                                                                                                   |
| 7       | Section 7 of the manual provides **overviews on various topics**, and describes conventions and protocols, character set standards, the standard filesystem layout, and miscellaneous other things.                                                                                                                                                                                                                                  |

## Encoding videos with ffmpeg

This is not an Arch way of encoding videos, but since I do this on my...

```console
$ ffmpeg -i <input> -c:v libx264 -b:v 1M -maxrate 1M -bufsize 2M -pass 1 -f null /dev/null
$ ffmpeg -i <input> -c:v libx264 -b:v 1M -maxrate 1M -bufsize 2M -pass 2 <output>
```